Post-transition metal

Post-transition metals in the periodic table   Elements classified as post-transition metals by Masterton, Hurley and Neth:[1] Ga, In, Tl, Sn, Pb, Bi, Po   Also recognised by Huheey, Keiter and Keiter:[2] Al, Ge, Sb, Po; and by Cox:[3] Zn, Cd, Hg   Also recognised by Deming:[4] Cu, Ag, Au (but he counted Al and groups 1 and 2 as 'light metals')[n 1]   Elements that might be post-transition metals: At, Cn, Uut, Fl, Uup, Lv, Uus

In chemistry, post-transition metals are the metallic elements in the periodic table located between the transition metals (to their left) and the metalloids (to their right). Usually included in this category are gallium, indium and thallium; tin and lead; and bismuth. Which elements are counted as post-transition metals depends, in periodic table terms, on where the transition metals are taken to end and where the metalloids or non-metals are taken to start.

Physically, post-transition metals are soft (or brittle), have poor mechanical strength, and melting points lower than those of the transition metals; most also have boiling points lower than those of the transition metals. Being close to the metal-nonmetal border, their crystalline structures tend to show covalent or directional bonding effects, having generally greater complexity or fewer nearest neighbours than other metallic elements.

Chemically, they are characterised—to varying degrees—by covalent bonding tendencies, acid-base amphoterism and the formation of anionic species such as aluminates, stannates, and bismuthates (in the case of aluminium, tin, and bismuth, respectively). They can also form Zintl phases (half-metallic compounds formed between highly electropositive metals and moderately electronegative metals or metalloids).

The expression 'post-transition metals' is used here as there is no IUPAC-approved collective name for these metals. Occasionally, some or all of them have instead been referred to as B-subgroup metals, other metals, or p-block metals; and by at least eleven other alternative labels. All these labels are surveyed later in this article.

Applicable elements

Scatter plot of electronegativity values and melting points for metals (up to fermium, element 100) and some borderline elements (Ge, As, Sb, At). Elements categorised by some authors as post-transition metals are distinguished by their relatively high electronegativity values and relatively low melting points. High electronegativity corresponds to increasing nonmetallic character;^[8] low melting temperature corresponds to weaker cohesive forces between atoms and reduced mechanical strength.^[9] The geography of the plot broadly matches that of the periodic table. Starting from the bottom left, and proceeding clockwise, the alkali metals are followed by the heavier alkaline earth metals; the rare earths and actinides (Sc, Y and the lanthanides being here treated as rare earths); transition metals with intermediate electronegativity values and melting points; the refractory metals; the platinum group metals; and the coinage metals leading and forming a part of the post-transition metals. The increased electropositivity of Be and Mg and the higher melting point of Be distances these light alkaline earth metals from their heavier congeners. This separation extends to other differences in physical and chemical behaviour between the light and heavier alkaline earth metals.^{[n 2]}

Usually included in this category are the group 13–15 metals: gallium, indium and thallium; tin and lead; and bismuth. Other elements sometimes included are copper, silver and gold (which are usually considered to be transition metals); zinc, cadmium and mercury (which are otherwise considered to be transition metals); and aluminium, germanium, arsenic and antimony (the latter three of which are usually considered to be metalloids). Astatine, which is usually classified as a nonmetal or a metalloid, has been predicted to have a metallic crystalline structure. If so, it would be a post-transition metal. Elements 113–117 may be post-transition metals; insufficient quantities of them have been synthesized to allow investigation of their actual physical and chemical properties.

Which elements start to be counted as post-transition metals depends, in periodic table terms, on where the transition metals are taken to end.^{[n 3]} In the 1950s, most inorganic chemistry textbooks defined transition elements as finishing at group 10 (nickel, palladium and platinum), therefore excluding group 11 (copper, silver and gold), and group 12 (zinc, cadmium and mercury). A survey of chemistry books in 2003 showed that the transition metals ended at either group 11 or group 12 with roughly equal frequency.^[13] Where the post-transition metals end depends on where the metalloids or nonmetals start. Boron, silicon, germanium, arsenic, antimony and tellurium are commonly recognised as metalloids; other authors treat some or all of these elements as nonmetals.

Rationale

The diminished metallic nature of the post-transition metals is largely attributable to the increase in nuclear charge going across the periodic table, from left to right.^[14] The increase in nuclear charge is partially offset by an increasing number of electrons but as these are spatially distributed each extra electron does not fully screen each successive increase in nuclear charge, and the latter therefore dominates.^[15] With some irregularities, atomic radii contract, ionisation energies increase,^[14] fewer electrons become available for metallic bonding,^[16] and "ions [become] smaller and more polarizing and more prone to covalency."^[17] This phenomenon is more evident in period 4–6 post-transition metals, due to inefficient screening of their nuclear charges by their d¹⁰ and (in the case of the period 6 metals) f¹⁴ electron configurations;^[18] the screening power of electrons decreases in the sequence s > p > d > f. The reductions in atomic size due to the interjection of the d- and f-blocks are referred to as, respectively, the 'scandide' or 'd-block contraction',^{[n 4]} and the 'lanthanide contraction'.^[19] Relativistic effects also "increase the binding energy", and hence ionisation energy, of the electrons in "the 6s shell in gold and mercury, and the 6p shell in subsequent elements of period 6."^[20]

Nomenclature

Origin

The origin of the term post-transition metal is unclear. An early usage is recorded by Deming, in 1940, in his well-known^[21] book Fundamental Chemistry.^[4] He treated the transition metals as finishing at group 10 (nickel, palladium and platinum). He referred to the ensuing elements in periods 4 to 6 of the periodic table (copper to germanium; silver to antimony; gold to polonium)—in view of their underlying d¹⁰ electronic configurations—as post-transition metals.

Descriptive chemistry

This section outlines relevant physical and chemical properties of the elements typically or sometimes classified as post-transition metals. For complete profiles, including history, production, specific uses, and biological roles and precautions, see the main article for each element. Abbreviations: MH—Mohs hardness; BCN—bulk coordination number.^{[n 5]}

Group 11

The group 11 metals are typically categorised as transition metals given they can form ions with incomplete d-shells. Physically, they have the relatively low melting points and high electronegativity values associated with post-transition metals. "The filled d subshell and free s electron of Cu, Ag, and Au contribute to their high electrical and thermal conductivity. Transition metals to the left of group 11 experience interactions between s electrons and the partially filled d subshell that lower electron mobility."^[24] Chemically, the group 11 metals in their +1 valence states show similarities to other post-transition metals;^[25] they are occasionally classified as such.^[26]

Copper

Silver

Gold

Copper is a soft metal (MH 2.5–3.0)^[27] with low mechanical strength.^[28] It has a close-packed face-centred cubic structure (BCN 12).^[29] Copper behaves like a transition metal in its preferred oxidation state of +2. Stable compounds in which copper is in its less preferred oxidation state of +1 (Cu₂O, CuCl, CuBr, CuI and CuCN, for example) have significant covalent character.^[30] The oxide (CuO) is amphoteric, with predominating basic properties; it can be fused with alkali oxides (M₂O; M = Na, K) to give anionic oxycuprates (M₂CuO₂).^[31] Copper forms Zintl phases such as Li₇CuSi₂^[32] and M₃Cu₃Sb₄ (M = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, or Er).^[33]

Silver is a soft metal (MH 2.5–3)^[34] with low mechanical strength.^[35] It has a close-packed face-centred cubic structure (BCN 12).^[36] The chemistry of silver is dominated by its +1 valence state in which it shows generally similar physical and chemical properties to compounds of thallium, a main group metal, in the same oxidation state.^[37] It tends to bond covalently in most of its compounds.^[38] The oxide (Ag₂O) is amphoteric, with basic properties predominating.^[39] Silver forms a series of oxoargentates (M₃AgO₂, M = Na, K, Rb).^[40] It is a constituent of Zintl phases such as Li₂AgM (M = Al, Ga, In, Tl, Si, Ge, Sn or Pb)^[41] and Yb₃Ag₂.^[42]

Gold is a soft metal (MH 2.5–3)^[43] that is easily deformed.^[44] It has a close-packed face-centred cubic structure (BCN 12).^[36] The chemistry of gold is dominated by its +3 valence state; all such compounds of gold feature covalent bonding,^[45] as do its stable +1 compounds.^[46] Gold oxide (Au₂O₃) is amphoteric, with acid properties predominating; it forms anionic hydroxoaurates M[Au(OH)₄] where M = Na, K, ¹⁄₂Ba, Tl; and aurates such as NaAuO₂.^[47] Gold is a constituent of Zintl phases such as M₂AuBi (M = Li or Na);^[48] Li₂AuM (M = In, Tl, Ge, Pb, Sn)^[49] and Ca₅Au₄.^[42]

Group 12

On the group 12 transition metals (zinc, cadmium and mercury), Smith^[50] observed that, "Textbook writers have always found difficulty in dealing with these elements." There is an abrupt and significant reduction in physical metallic character from group 11 to group 12.^[51] Their chemistry is that of main group elements.^[52] A 2003 survey of chemistry books showed that they were treated as either transition metals or main group elements on about a 50/50 basis.^{[13][n 6]} The IUPAC Red Book notes that although the group 3−12 elements are commonly referred to as the transition elements, the group 12 elements are not always included.^[54] The group 12 elements do not satisfy the IUPAC Gold Book definition of a transition metal^{[55][n 7]} (other than in the case of mercury at 4 K).

Zinc

Cadmium

Mercury

Zinc is a soft metal (MH 2.5) with poor mechanical properties.^[57] It has a crystalline structure (BCN 6+6) that is slightly distorted from the ideal. Many zinc compounds are markedly covalent in character.^[58] The oxides of zinc in its preferred oxidation state of +2, namely ZnO and Zn(OH)₂, are amphoteric;^[59] it forms anionic zincates in strongly basic solutions.^[60] Zinc forms Zintl phases such as LiZn, NaZn₁₃ and BaZn₁₃.^[61] Highly purified zinc, at room temperature, is ductile.^[62] It reacts with moist air to form a thin layer of carbonate that prevents further corrosion.^[63]

Cadmium is a soft, ductile metal (MH 2.0) that undergoes substantial deformation, under load, at room temperature.^[64] Like zinc, it has a crystalline structure (BCN 6+6) that is slightly distorted from the ideal. The halides of cadmium, with the exception of the fluoride, exhibit a substantially covalent nature.^[65] The oxides of cadmium in its preferred oxidation state of +2, namely CdO and Cd(OH)₂, are weakly amphoteric; it forms cadmates in strongly basic solutions.^[66] Cadmium forms Zintl phases such as LiCd, RbCd₁₃ and CsCd₁₃.^[61] When heated in air to a few hundred degrees, cadmium represents a toxicity hazard due to the release of cadmium vapour; when heated to its boiling point in air (just above 1000 K; 725 C; 1340 F; cf steel ~2700 K; 2425 C; 4400 F),^[67] the cadmium vapour oxidizes, 'with a reddish-yellow flame, dispersing as an aerosol of potentially lethal CdO particles.'^[64] Cadmium is otherwise stable in air and in water, at ambient conditions, protected by a layer of cadmium oxide.

Mercury is a liquid at room temperature. It has the weakest metallic bonding of all, as indicated by its bonding energy (61 kJ/mol) and melting point (−39 °C) which, together, are the lowest of all the metallic elements.^{[68][n 8]} Solid mercury (MH 1.5)^[69] has a distorted crystalline structure,^[70] with mixed metallic-covalent bonding,^[71] and a BCN of 6. "All of the [Group 12] metals, but especially mercury, tend to form covalent rather than ionic compounds."^[72] The oxide of mercury in its preferred oxidation state (HgO; +2) is weakly amphoteric, as is the congener sulfide HgS.^[73] It forms anionic thiomercurates (such as Na₂HgS₂ and BaHgS₃) in strongly basic solutions.^{[74][n 9]} It forms or is a part of Zintl phases such as NaHg and K₈In₁₀Hg.^[75] Mercury is a relatively inert metal, showing little oxide formation at room temperature.^[76]

Group 13

Aluminium

Gallium

Indium

Thallium

Aluminium sometimes is^[77] or is not^[3] counted as a post-transition metal. It has a well shielded [Ne] noble gas core rather than the less well shielded [Ar]3d¹⁰, [Kr]4d¹⁰ or [Xe]4f¹⁴5d¹⁰ core of the post-transition metals. The small radius of the aluminium ion combined with its high charge make it a strongly polarizing species, prone to covalency.^[78]

Aluminium in pure form is a soft metal (MH 3.0) with low mechanical strength.^[79] It has a close-packed structure (BCN 12) showing some evidence of partially directional bonding.^{[80][n 10]} It has a low melting point and a high thermal conductivity. Its strength is halved at 200 °C, and for many of its alloys is minimal at 300 °C.^[82] The latter three properties of aluminium limit its use to situations where fire protection is not required,^[83] or necessitate the provision of increased fire protection.^{[84][n 11]} It bonds covalently in most of its compounds;^[88] has an amphoteric oxide; and can form anionic aluminates.^[60] Aluminium forms Zintl phases such as LiAl, Ca₃Al₂Sb₆, and SrAl₂.^[89] A thin protective layer of oxide confers a reasonable degree of corrosion resistance.^[90] It is susceptible to attack in low pH (<4) and high (> 8.5) pH conditions,^{[91][n 12]} a phenomenon that is generally more pronounced in the case of commercial purity aluminium and aluminium alloys.^[97] Given many of these properties and its proximity to the dividing line between metals and nonmetals, aluminium is occasionally classified as a metalloid.^{[n 13]} Despite its shortcomings, it has a good strength-to-weight ratio and excellent ductility; its mechanical strength can be improved considerably with the use of alloying additives; its very high thermal conductivity can be put to good use in heat sinks and heat exchangers;^[98] and it has a high electrical conductivity.^{[n 14]} At lower temperatures, aluminium increases its deformation strength (as do most materials) whilst maintaining ductility (as do face-centred cubic metals generally).^[100] Chemically, bulk aluminium is a strongly electropositive metal, with a high negative electrode potential.^{[101][n 15]}

Gallium is a soft, brittle metal (MH 1.5) that melts at only a few degrees above room temperature.^[103] It has an unusual crystalline structure featuring mixed metallic-covalent bonding and low symmetry^[103] (BCN 7 i.e. 1+2+2+2).^[104] It bonds covalently in most of its compounds,^[105] has an amphoteric oxide;^[106] and can form anionic gallates.^[60] Gallium forms Zintl phases such as Li₂Ga₇, K₃Ga₁₃ and YbGa₂.^[107] It is slowly oxidized in moist air at ambient conditions; a protective film of oxide prevents further corrosion.^[108]

Indium is a soft, highly ductile metal (MH 1.0) with a low tensile strength.^[109][110] It has a partially distorted crystalline structure (BCN 4+8) associated with incompletely ionised atoms.^[111] The tendency of indium '...to form covalent compounds is one of the more important properties influencing its electrochemical behavior'.^[112] The oxides of indium in its preferred oxidation state of +3, namely In₂O₃ and In(OH)₃ are weakly amphoteric; it forms anionic indates in strongly basic solutions.^[113] Indium forms Zintl phases such as LiIn, Na₂In and Rb₂In₃.^[114] Indium does not oxidize in air at ambient conditions.^[110]

Thallium is a soft, reactive metal (MH 1.0), so much so that it has no structural uses.^[115] It has a close-packed crystalline structure (BCN 6+6) but an abnormally large interatomic distance that has been attributed to partial ionisation of the thallium atoms.^[116] Although compounds in the +1 (mostly ionic) oxidation state are the more numerous, thallium has an appreciable chemistry in the +3 (largely covalent) oxidation state, as seen in its chalcogenides and trihalides.^[117] It is the only one of the Group 13 elements to react with air at room temperature, slowly forming the amphoteric oxide Tl₂O₃.^{[118][119][120]} It forms anionic thallates such as Tl₃TlO₃, Na₃Tl(OH)₆, NaTlO₂, and KTlO₂,^[119] and is present as the Tl⁻ thallide anion in the compound CsTl.^[121] Thallium forms Zintl phases, such as Na₂Tl, Na₂K₂₁Tl₁₉, CsTl and Sr₅Tl₃H.^[122]

Group 14

Germanium

Tin

Lead

Germanium is a hard (MH 6), very brittle semi-metallic element.^[123] It was originally thought to be a poorly conducting metal^[124] but has the electronic band structure of a semiconductor.^[125] Germanium is usually considered to be a metalloid rather than a metal.^[126] Like carbon (as diamond) and silicon, it has a covalent tetrahedral crystalline structure (BCN 4).^[127] Compounds in its preferred oxidation state of +4 are covalent.^[128] Germanium forms an amphoteric oxide, GeO₂^[129] and anionic germanates, such as Mg₂GeO₄.^[130] It forms Zintl phases such as LiGe, K₈Ge₄₄ and La₄Ge₃.^[131]

Tin is a soft, exceptionally^[132] weak metal (MH 1.5);^{[n 16]} a 1-cm thick rod will bend easily under mild finger pressure.^[132] It has an irregularly coordinated crystalline structure (BCN 4+2) associated with incompletely ionised atoms.^[111] All of the Group 14 elements form compounds in which they are in the +4, predominantly covalent, oxidation state; even in the +2 oxidation state tin generally forms covalent bonds.^[134] The oxides of tin in its preferred oxidation state of +2, namely SnO and Sn(OH)₂, are amphoteric;^[135] it forms stannites in strongly basic solutions.^[60] Below 13 °C (55.4 °F) tin changes its structure and becomes 'grey tin', which has the same structure as diamond, silicon and germanium (BCN 4). This transformation causes ordinary tin to crumble and disintegrate since, as well as being brittle, grey tin occupies more volume due to having a less efficient crystalline packing structure. Tin forms Zintl phases such as Na₄Sn, BaSn, K₈Sn₂₅ and Ca₃₁Sn₂₀.^[136] It has good corrosion resistance in air on account of forming a thin protective oxide layer. Pure tin has no structural uses.^[137] It is used in lead-free solders, and as a hardening agent in alloys of other metals, such as copper, lead, titanium and zinc.^[138]

Lead is a soft metal (MH 1.5)(but hardens close to melting) which, in many cases,^[139] is unable to support its own weight.^[140] It has a close-packed structure (BCN 12) but an abnormally large inter-atomic distance that has been attributed to partial ionisation of the lead atoms.^[116][141] It forms a semi-covalent dioxide PbO₂; a covalently bonded sulfide PbS; covalently bonded halides;^[142] and a range of covalently bonded organolead compounds such as the lead(II) mercaptan Pb(SC₂H₅)₂, lead tetra-acetate Pb(CH₃CO₂)₄, and the once common, anti-knock additive, tetra-ethyl lead (CH₃CH₂)₄Pb.^[143] The oxide of lead in its preferred oxidation state (PbO; +2) is amphoteric;^[144] it forms anionic plumbates in strongly basic solutions.^[60] Lead forms Zintl phases such as CsPb, Sr₃₁Pb₂₀, La₅Pb₃N and Yb₃Pb₂₀.^[145] It has reasonable to good corrosion resistance; in moist air it forms a mixed gray coating of oxide, carbonate and sulfate that hinders further oxidation.^[146]

Group 15

Arsenic

Antimony

Bismuth

Arsenic is a moderately hard (MH 3.5) and brittle semi-metallic element. It is commonly regarded as a metalloid, or by some other authors as either a metal or a non-metal. It exhibits poor electrical conductivity which, like a metal, decreases with temperature. It has a relatively open and partially covalent crystalline structure (BCN 3+3). Arsenic forms covalent bonds with most other elements. The oxide in its preferred oxidation state (As₂O₃, +3) is amphoteric,^{[n 17]} as is the corresponding oxoacid in aqueous solution (H₃AsO₃) and congener sulphide (As₂S₃). Arsenic forms a series of anionic arsenates such as Na₃AsO₃ and PbHAsO₄, and Zintl phases such as Na₃As, Ca₂As and SrAs₃.

Antimony is a soft (MH 3.0) and brittle semi-metallic element. It is commonly regarded as a metalloid, or by some other authors as either a metal or a non-metal. It exhibits poor electrical conductivity which, like a metal, decreases with temperature. It has a relatively open and partially covalent crystalline structure (BCN 3+3). Antimony forms covalent bonds with most other elements. The oxide in its preferred oxidation state (Sb₂O₃, +3) is amphoteric. Antimony forms a series of anionic antimonites and antimonates such as NaSbO₂ and AlSbO₄, and Zintl phases such as K₅Sb₄, Sr₂Sb₃ and BaSb₃.

Bismuth is a slightly radioactive, soft metal (MH 2.5) that is too brittle for any structural use.^[149] It has an open-packed crystalline structure (BCN 3+3) with bonding that is intermediate between metallic and covalent.^[150] For a metal, it has exceptionally low electrical and thermal conductivity.^[151] Most of the ordinary compounds of bismuth are covalent in nature.^[152] The oxide, Bi₂O₃ is predominantly basic but will act as a weak acid in warm, very concentrated KOH.^[153] It can also be fused with potassium hydroxide in air, resulting in a brown mass of potassium bismuthate.^[154] The solution chemistry of bismuth is characterised by the formation of oxyanions;^[155] it forms anionic bismuthates in strongly basic solutions.^[156] Bismuth forms Zintl phases such as NaBi,^[157] Rb₇In₄Bi₆^[158] and Ba₁₁Cd₈Bi₁₄.^[159] Bailar et al.^[160] refer to bismuth as being, 'the least "metallic" metal in its physical properties' given its brittle nature (and possibly) 'the lowest electrical conductivity of all metals.'^{[n 18]}

Group 16

Polonium is a radioactive, soft metal with a hardness similar to lead.^[162] It has a simple cublc crystalline structure characterised (as determined by electron density calculations) by partially directional bonding,^[163] and a BCN of 6. Such a structure ordinarily results in very low ductility and fracture resistance^[164] however polonium has been predicted to be a ductile metal.^[165] It forms a covalent hydride;^[166] its halides are covalent, volatile compounds, resembling those of tellurium.^[167] The oxide of polonium in its preferred oxidation state (PoO₂; +4) is predominantly basic, but amphoteric if dissolved in concentrated aqueous alkali, or fused with potassium hydroxide in air.^[168] The yellow polonate(IV) ion PoO2−
3 is known in aqueous solutions of low Cl^‒ concentration and high pH.^{[169][n 19]} Polonides such as Na₂Po, BePo, ZnPo, CdPo and HgPo feature Po²⁻ anions;^[171] except for HgPo these are some of the more stable of the polonium compounds.^{[172][n 20]}

Group 17

Astatine is a radioactive element that has never been seen; a visible quantity would immediately be vapourized due to its intense radioactivity.^[174] It may be possible to prevent this with sufficient cooling.^[175] Astatine is commonly regarded as a nonmetal,^[176] less commonly as a metalloid^[177] and occasionally as a metal. Unlike its lighter congener iodine, evidence for diatomic astatine is sparse and inconclusive.^[178] In 2013, on the basis of relativistic modelling, astatine was predicted to be a monatomic metal, with a face-centered cubic crystalline structure.^[175] As such, astatine could be expected to have a metallic appearance; show metallic conductivity; and have excellent ductility, even at cryogenic temperatures.^[179] It could also be expected to show significant nonmetallic character, as is normally the case for metals in, or in the vicinity of, the p-block. Astatine oxyanions AtO⁻, AtO−
2, AtO−
3 and AtO−
4 are known,^[180] oxyanion formation being a tendency of nonmetals.^[181] The hydroxide of astatine At(OH) is presumed to be amphoteric.^{[182][n 21]} Astatine forms covalent compounds with nonmetals,^[185] including hydrogen astatide HAt and carbon tetraastaide CAt₄.^{[186][n 22]} At⁻ anions have been reported to form astatides with silver, thallium, palladium and lead.^[188] Pruszyński et al. note that astatide ions should form strong complexes with soft metal cations such as Hg²⁺, Pd²⁺, Ag⁺ and Tl³⁺; they list the astatide formed with mercury as Hg(OH)At.^[189]

Related groupings

B-subgroup metals

Superficially, the B-subgroup metals are the metals in Groups IB to VIB of the periodic table, corresponding to Groups 11 to 16 using current IUPAC nonmenclature. Practically, the group 11 metals (copper, silver and gold) are ordinarily regarded as transition metals (or sometimes as coinage metals, or noble metals) whereas the group 12 metals (zinc, cadmium, and mercury) may or may not be treated as B-subgroup metals depending on if the transition metals are taken to end at group 11 or group 12. The 'B' nomenclature (as in Groups IB, IIB, and so on) was superseded in 1988 but is still occasionally encountered in more recent literature.^{[190][n 23]}

The B-subgroup metals show nonmetallic properties; this is particularly apparent in moving from group 12 to group 16.^[192] Although the group 11 metals have normal close-packed metallic structures^[193] they show an overlap in chemical properties. In their +1 compounds (the stable state for silver; less so for copper)^[194] they are typical B-subgroup metals. In their +2 and +3 states their chemistry is typical of transition metal compounds.^[195]

Borderline metals

Parish^[196] writes that, 'as anticipated', the borderline metals of groups 13 and 14 have non-standard structures. Gallium, indium, thallium, germanium, and tin are specifically mentioned in this context. The group 12 metals are also noted as having slightly distorted structures; this has been interpreted as evidence of weak directional (i.e. covalent) bonding.^{[n 24]}

Chemically weak metals

Rayner-Canham and Overton^[198] use the term chemically weak metals to refer to the metals close to the metal-nonmetal borderline. These metals behave chemically more like the metalloids, particularly with respect to anionic species formation. The nine chemically weak metals identified by them are beryllium, aluminium, zinc, gallium, tin, lead, antimony, bismuth, and polonium.^{[n 25]}

Fusible metals

Cardarelli,^[200] writing in 2008, categorizes zinc, cadmium, mercury, gallium, indium thallium, tin, lead, antimony and bismuth as fusible metals. Nearly 100 years earlier, Louis (1911)^[201] noted that fusible metals were alloys containing tin, cadmium, lead, and bismuth in various proportions, "the tin ranging from 10 to 20%."

Heavy metals (of low melting point)

Van Wert^[202] grouped the periodic table metals into a. the light metals; b. the heavy brittle metals of high melting point, c. the heavy ductile metals of high melting point; d. the heavy metals of low melting point (Zn, Cd, Hg; Ga, In, Tl; Ge, Sn; As, Sb, Bi; and Po), and e. the strong, electropositive metals. Britton, Abbatiello and Robins^[203] speak of 'the soft, low melting point, heavy metals in columns lIB, IlIA, IVA, and VA of the periodic table, namely Zn, Cd, Hg; Al, Ga, In, Tl; [Si], Ge, Sn, Pb; and Bi. The Sargent-Welch Chart of the Elements groups the metals into: light metals, the lanthanide series; the actinide series; heavy metals (brittle); heavy metals (ductile); and heavy metals (low melting point): Zn, Cd, Hg, [Cn]; Al, Ga, In, Tl; Ge, Sn, Pb, [Fl]; Sb, Bi; and Po.^{[204][n 26]}

Less typical metals

Habashi^[206] groups the elements into eight major categories: [1] typical metals (alkali metals, alkaline earth metals, and aluminium); [2] lanthanides (Ce–Lu); [3] actinides (Th–Lr); [4] transition metals (Sc, Y, La, Ac, groups 4–10); [5] less typical metals (groups 11–12, Ga, In, Tl, Sn and Pb); [6] metalloids (B, Si, Ge, As, Se, Sb, Te, Bi and Po); [7] covalent nonmetals (H, C, N, O, P, S and the halogens); and [8] monatomic nonmetals (that is, the noble gases).

Metametals

The metametals are zinc, cadmium, mercury, indium, thallium, tin and lead. They are ductile elements but, compared to their metallic periodic table neighbours to the left, have lower melting points, relatively low electrical and thermal conductivities, and show distortions from close-packed forms.^[207] Sometimes beryllium^[208] and gallium^[209] are included as metametals despite having low ductility.

Ordinary metals

Abrikosov^[210] distinguishes between ordinary metals, and transition metals where the inner shells are not filled. The ordinary metals have lower melting points and cohesive energies than those of the transition metals.^[211] Gray^[212] identifies as ordinary metals: aluminium, gallium, indium, thallium, element 113, tin, lead, [flerovium], bismuth, element 115, and [livermorium]. He adds that, 'in reality most of the metals that people think of as ordinary are in fact transition metals...'.

Other metals

As noted, the metals falling between the transition metals and the metalloids on the periodic table are sometimes called other metals (see also, for example, Taylor et al.).^[213] 'Other' in this sense has the related meanings of, 'existing besides, or distinct from, that already mentioned'^[214] (that is, the alkali and alkaline earth metals, the lanthanides and actinides, and the transition metals); 'auxiliary'; 'ancillary, secondary'.^[215] According to Gray^[216] there should be a better name for these elements than 'other metals'.

P-block metals

The p-block metals are the metals in groups 13‒15 (or 16) of the periodic table. Usually, this includes aluminium, gallium, indium and thallium; tin and lead; and bismuth. Germanium, antimony and polonium are sometimes also included, although the first two are commonly recognised as metalloids. The p-block metals tend to have structures that display low coordination numbers and directional bonding. Pronounced covalency is found in their compounds; the majority of their oxides are amphoteric.^[217]

Peculiar metals

Slater^[218] divides the metals 'fairly definitely, though not perfectly sharply' into the ordinary metals and the peculiar metals, the latter of which verge on the nonmetals. The peculiar metals occur towards the ends of the rows of the periodic table and include 'approximately:' gallium, indium, and thallium; carbon, silicon '(both of which have some metallic properties, though we have previously treated them as nonmetals),' germanium and tin; arsenic, antimony, and bismuth; and selenium '(which is partly metallic)' and tellurium. The ordinary metals have centro-symmetrical crystalline structures^{[n 27]} whereas the peculiar metals have structures involving directional bonding. More recently, Joshua observed that the peculiar metals have mixed metallic-covalent bonding.^[220]

Poor metals

Farrell and Van Sicien^[221] use the term poor metal, for simplicity, 'to denote one with a significant covalent, or directional character.' Hill and Holman^[222] observe that, 'The term poor metals is not widely used, but it is a useful description for several metals including tin, lead and bismuth. These metals fall in a triangular block of the periodic table to the right of the transition metals. They are usually low in the activity (electrochemical) series and they have some resemblances to non-metals.' Reid et al.^[223] write that 'poor metals' is, '[A]n older term for metallic elements in Groups 13‒15 of the periodic table that are softer and have lower melting points than the metals traditionally used for tools.'

Semimetals

In modern use, the term 'semimetal' sometimes refers, loosely or explicitly, to metals with incomplete metallic character in crystalline structure, electrical conductivity or electronic structure. Examples include gallium,^[224] ytterbium,^[225] bismuth,^[226] mercury^[227] and neptunium.^[228] Metalloids, which are in-between elements that are neither metals nor nonmetals, are also sometimes instead called semimetals. The elements commonly recognised as metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. In old chemistry, before the publication in 1789 of Lavoisier's 'revolutionary'^[229] Elementary Treatise on Chemistry,^[230] a semimetal was a metallic element with 'very imperfect ductility and malleability'^[231] such as zinc, mercury or bismuth.

Transition metals

Historically, the transition metal series "includes those elements of the Periodic Table which 'bridge the gap' between the very electropositive alkali and allkaline earth metals and the electronegative non-metals of the groups: nitrogen-phosphorus, oxygen-sulfur, and the halogens."^[232] Cheronis, Parsons and Ronneberg^[233] wrote that, "The transition metals of low melting point form a block in the Periodic Table: those of Groups II 'b' [zinc, cadmium, mercury], III 'b' [aluminium, gallium, indium, thallium], and germanium, tin and lead in Group IV. These metals all have melting points below 425 °C."^{[n 28]}

Notes

1. More recent examples of authors who treat Cu, Ag and Au as post-transition metals include Subba Rao & Shafer;^[5] Collings;^[6] and Temkin.^[7]
2. Physical properties: "The lighter alkaline earths possess fairly high electrical and thermal conductivities and sufficient strength for structural use. The heavier elements are poor conductors and are too weak and reactive for structural use."^[10] Chemical: The lighter alkaline earths show covalent bonding tendencies (Be predominantly; Mg considerably) whereas compounds of the heavier alkaline earths are predominantly ionic in nature; the heavier alkaline earths have more stable hydrides and less stable carbides.^[11]
3. A first IUPAC definition states "[T]he elements of groups 3–12 are the d-block elements. These elements are also commonly referred to as the transition elements, though the elements of group 12 are not always included". Depending on the inclusion of group 12 as transition metals, the post-transition metals therefore may or may not include the group 12 elements—zinc, cadmium, and mercury. A second IUPAC definition for transition metals states "An element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Based on this definition one could argue group 12 should be split with mercury and probably also copernicium as transition metals, and zinc and cadmium as post-transition metals. Of relevance is the synthesis of mercury(IV) fluoride, which seemingly establishes mercury as a transition metal. This conclusion has been challenged by Jensen^[12] with the argument that HgF₄ only exists under highly atypical non-equilibrium conditions (at 4 K) and should best be considered as an exception. Copernicium is predicted to have (a) an electron configuration similar to that of mercury; and (b) a predominance of its chemistry in the +4 state, and on that basis would be regarded as a transition metal.
4. The scandide contraction refers to the first row transition metals; the d-block contraction is a more general term.
5. Moh's hardness values are taken from Samsanov,^[22] unless otherwise noted; bulk coordination number values are taken from Darken and Gurry,^[23] unless otherwise noted.
6. The group 12 metals have been treated as transition metals for reasons of historical precedent, to compare and contrast properties, to preserve symmetry, or for basic teaching purposes.^[53]
7. The IUPAC Gold Book defines a transition metal as 'An element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell.^[56]
8. Francium may have a comparably low bonding energy but its melting point of around 27°C is significantly higher than that of mercury, at −39°C.
9. Mercury also forms partially anionic oxomercurates, such as Li₂HgO₂ and CdHgO₄, by heating mixtures of HgO with the relevant cation oxides, including under oxygen pressure (Müller-Buschbaum 1995; Deiseroth 2004, pp. 173, 177, 185–186).
10. The partially directional bonding in aluminium improves its shear strength but means that ultrahigh-purity aluminium cannot maintain work hardening at room temperature.^[81]
11. Without the use of thermal insulation and detailed structural design attention,^[85] aluminium's low melting point and high thermal conductivity mitigate against its use, for example, in military ship construction—should a ship burn, the low melting point results in structural collapse; the high thermal conductivity helps spread the fire.^[86] Its use in the construction of cargo ships is limited as little or no economic advantage is gained over steel, once the cost and weight of fitting thermal insulation is taken into account.^[87]
12. Aluminium can be attacked, for example, by alkaline detergents^[92] (including those used in dishwashers);^[93] by wet concrete,^[94] and by highly acidic foods such as tomatoes, rhubarb or cabbage.^[95] It is not attacked by nitric acid.^[96]
13. See the list of metalloid lists for references
14. Aluminium wire is used in electrical transmisson lines for the distribution of power but, on account of its low breaking strength, is refinforced with a central core of galvanised steel wire.^[99]
15. In the absence of protective measures, the relatively high electropositivity of aluminium renders it susceptible to galvanic corrosion when in physical or electrical contact with other metals such as copper or steel, especially when exposed to saline media, such as sea water or wind-blown sea spray.^[102]
16. Charles, Crane and Furness write that, 'Most metals, except perhaps lead and tin, can be alloyed to give [yield] strengths that lie in the upper two-thirds of the low-strength range…'^[133]
17. As₂O₃ is usually regarded as being amphoteric but a few sources say it is (weakly)^[147] acidic. They describe its "basic" properties (its reaction with concentrated hydrochloric acid to form arsenic trichloride) as being alcoholic, in analogy with the formation of covalent alkyl chlorides by covalent alcohols (e.g., R-OH + HCl → RCl + H₂O)^[148]
18. Which metal has the lowest electrical conductivity is debatable but bismuth is certainly in the lowest cohort; Hoffman^[161] refers to bismuth as 'a poor metal, on the verge of being a semiconductor.'
19. Bagnall^[170] writes that the fusion of polonium dioxide with a potassium chlorate/hydroxide mixture yields a bluish solid which, '...presumably contains some potassium polonate.'
20. Bagnall^[173] noted that the rare-earth polonides have the greatest thermal stability of any polonium compound.
21. Eagleson refers to the OH compound of astatine as hypoastatous acid HAtO;^[183] Pimpentel and Spratley give the formula for hypoastatous acid as HOAt.^[184]
22. In hydrogen astatide the negative charge is predicted to be on the hydrogen atom,^[187] implying that this compound should instead be referred to as astatine hydride (AtH).
23. Greenwood and Earnshaw^[191] refer to the B-subgroup metals as post-transition elements: 'Arsenic and antimony are classed as metalloids or semi-metals and bismuth is a typical B sub-group (post-transition-element) metal like tin and lead.'
24. Aluminium is identified by Parish, along with germanium, antimony and bismuth, as being a metal on the boundary line between metals and non-metals; he suggests that all these elements are 'probably better classed as metalloids.'^[197]
25. Pauling,^[199] in contrast, refers to the strong metals in Groups 1 and 2 (that form ionic compounds with 'the strong nonmetals in the upper right corner of the periodic table.').
26. Hawkes,^[205] attempting to address the question of what is a heavy metal, commented that, 'Being a heavy metal has little to do with density, but rather concerns chemical properties'. He observed that, 'It may mean different things to different people, but as I have used, heard and interpreted the term over the last half-century, it refers to metals with insoluble sulfides and hydroxides, whose salts produce colored solutions in water, and whose complexes are usually colored.' He goes on to note that, 'The metals I have seen referred to as heavy metals comprise a block of all the metals in Groups 3 to 16 that are in periods 4 and greater. It may also be stated as the transition metals and post-transition metals.
27. On manganese, Slater says, '[It] is a very peculiar and anomalous exception to the general order of the elements. It is the only definite metal, far from the nonmetals in the table, which has a complicated structure.'^[219]
28. In fact, both aluminium (660.32) and germanium (938.25) have melting points greater than 425°C.

Sources

Citations

1. Masterton, Hurley & Neth p. 38
2. Huheey, Keiter & Keiter 1993, p. 28
3. Cox 2004, p. 186
4. Deming 1940, p. 704–715
5. Subba Rao & Shafer 1979, p. 170
6. Collings 1986, p. 5
7. Temkin 2012, pp. 1, 726
8. Roher 2001, pp. 2‒3
9. Messler 2006, p. 347
10. Russell & Lee 2005, p. 165
11. Cotton et al. 1999, pp. 111–113; Greenwood & Earnshaw 2002, p. 111–113
12. Jensen 2008
13. Jensen 2003, p. 952
14. Cox 2004, p. 17
15. Atkins & de Paula 2011, p. 352
16. Greenwood & Earnshaw 1998, pp. 222–3
17. Steele 1966, p. 193
18. Johnson 1970
19. Huheey & Huheey 1972, p. 229; Mason 1988
20. Cox 2004, pp. 20, 186, 188
21. Science Education 1948, p. 120
22. Samsanov 1968
23. Darken & Gurry 1953, pp. 50–53
24. Russell & Lee 2005, p. 302
25. Steele 1966, p. 67
26. Deming 1940, pp. 705–7; Karamad, Tripkovic & Rossmeisl 2014
27. Cheemalapati, Keleher & Li 2008, p. 226
28. Liu & Pecht 2004, p. 54
29. Donohue 1982, p.&bsnp;222
30. Vanderah 1992, p. 52
31. Lidin 1996, p. 110
32. Slabon et al. 2012
33. Larson et al. 2006, p. 035111-2
34. Schumann 2008, p. 52
35. Braunović 2014, p. 244
36. Donohue 1982, p. 222
37. Banthorpe, Gatforde & Hollebone 1968, p. 61; Dillard & Goldberg 1971, p. 558
38. Steiner & Campbell 1955, p. 394
39. Lidin 1996, p. 5
40. Klassen & Hoppe 1982; Darriet, Devalette & Lecart 1977; Sofin et al. 2002
41. Goodwin et al. 2005, p. 341
42. Köhler & Whangbo 2008
43. Arndt & Ganino 2012, p. 115
44. Goffer 2007, p. 176
45. Sidgwick 1950, p. 177
46. Pauling 1988, p. 698
47. Lidin 1996, p. 21–22
48. Miller et al. 2011, p. 150
49. Fishcher-Bünher 2011, p. 150
50. Smith 1990, p. 113
51. Sorensen 1991, p. 3
52. King 1995, pp.  xiii, 273–288; Cotton et al. 1999, pp. ix, 598; Massey 2000, pp. 159–176
53. Young et al. 1969; Geffner 1969; Jensen 2003
54. IUPAC 2005, p. 51
55. Crichton 2012, p. 11
56. IUPAC 2006–, transition element entry
57. Schweitzer 2003, p. 603
58. Hutchinson 1964, p. 562
59. Greenwood & Earnshaw 1998, p. 1209; Gupta CK 2002, p. 590
60. Rayner-Canham & Overton 2006, p. 30
61. Kneip 1996, p. xxii
62. Russell & Lee 2005, p. 339
63. Sequeira 2013, p. 243
64. Russell & Lee 2005, p. 349
65. Borsari 2005, p. 608
66. Dirkse 1986, pp. 287–288, 296; Ivanov-Emin, Misel'son & Greksa 1960
67. Wanamaker & Pennington 1921, p. 56
68. Rayner-Canham 2006, p. 570; Chambers & Holliday 1975, p. 58; Wiberg, Holleman & Wiberg 2001, p. 247; Aylward & Findlay 2008, p. 4
69. Poole 2004, p. 821
70. Mittemeijer 2010, p. 138
71. Russell & Lee 2005, pp. 1–2; 354
72. Rayner-Canham 2006, p. 567
73. Moeller 1952, pp. 859, 866
74. Cooney & Hall 1966, p. 2179
75. Deiseroth 2008, pp. 179‒180; Sevov 1993
76. Russell & Lee 2005, p. 354
77. Whitten et al. 2014, p. 1045
78. Kneen, Rogers & Simpson 2004, p. 370;Cox 2004, p. 199
79. Gerard & King 1968, p. 16; Dwight 1999, p. 2
80. Russell & Lee 2005, pp. 1–2; 359
81. Ogata, Li & Yip 2002; Russell & Lee 2005, p. 360; Glaeser 1992, p. 224
82. Lyons 2004, p. 170
83. Cobb 2009, p. 323
84. Polemear 2006, p. 184
85. Holl 1989, p. 90
86. Ramroth 2006, p. 6; US Dept. of Transportation, Maritime Administration 1987, pp. 97, 358
87. Noble 1985, p. 21
88. Cooper 1968, p. 25; Henderson 2000, p. 5
89. Kauzlarich 2005, pp. 6009–10
90. Dennis & Such 1993, p. 391
91. Cramer & Covino 2006, p. 25
92. Hinton & Dobrota 1978, p. 37
93. Holman & Stone 2001, p. 141
94. Hurd 2005, p. 4-15
95. Vargel 2004, p. 580
96. Hill & Holman 2000, p. 276
97. Russell & Lee 2005, p. 360
98. Clegg & Dovaston 2003, p. 5/5
99. Liptrot 2001, p. 181
100. Kent 1993, pp. 13–14
101. Steele 1966, p. 60
102. Davis 1999, p. 75–7
103. Russell & Lee 2005, p. 387
104. Driess 2004, p. 151; Donohue 1982, p. 237
105. Walker, Enache & Newman 2013, p. 38
106. Atkins et al. 2006, p. 123
107. Corbett 1996, p. 161
108. Eranna 2012, p. 67
109. Chandler 1998, p. 59
110. Russell & Lee 2005, p. 389
111. Evans 1966, p. 129–130
112. Liang, King & White 1968, p. 288
113. Busev 1962, p. 33; Liang, King & White 1968, p. 287; Solov'eva et al. 1973, p. 43; Greenwood & Earnshaw 1998, p. 226; Leman & Barron 2005, p. 1522
114. Kneip 1996, p. xxii; Corbett 1996, pp. 153, 158
115. Russell & Lee 2005, p. 390
116. Wells 1985, p. 1279–80
117. Howe 1968a, p. 709; Taylor & Brothers 1993, p. 131; Lidin 1996, p. 410; Tóth & Győri 2005, pp. 4, 6–7
118. Chambers & Holliday 1975, p. 144
119. Bashilova & Khomutova 1984, p. 1546
120. Ropp 2012, p. 484
121. King & Schleyer 2004, p. 19
122. Corbett 1996, p. 153; King 2004, p. 199
123. Wiberg, Holleman & Wiberg 2001, p. 894
124. Haller 2006, p. 3
125. Russell & Lee 2005, p. 399
126. Ryan 1968, p. 65
127. Wiberg, Holleman & Wiberg 2001, p. 895
128. Abd-El-Aziz et al. 2003, p. 200
129. Cooper 1968, pp. 28–9
130. Ropp 2012, p. 405
131. Corbett 1996, p. 143
132. Russell & Lee 2005, p. 405
133. Charles, Crane & Furness 1997, pp. 49, 57
134. Rayner-Canham 2006, pp. 306, 340
135. Wiberg, Holleman & Wiberg 2001, p. 247
136. Corbett 1996, p. 143; Cotton et al. 1999, pp. 99, 122; Kauzlarich 2005, p. 6009
137. Russell & Lee 2005, pp. 402, 405
138. Russell & Lee 2005, p. 402, 407
139. Alhassan & Goodwin 2005, p. 532
140. Schweitzer 2003, p. 695
141. Mackay & Mackay 1989, p. 86; Norman 1997, p. 36
142. Hutchinson 1959, p. 455; Wells 1984, p. 1188; Liu, Knowles & Chang 1995, p. 125; Bharara & Atwood 2005, pp. 2, 4
143. Durrant & Durrant 1970, p. 670; Lister 1998, p. A12; Cox 2004, p. 204
144. Patnaik 2003, p. 474
145. Corbett 1996, pp. 143, 147; Cotton et al. 1999, p. 122; Kauzlarich 2005, p. 6009
146. Russell & Lee 2005, pp. 411, 13
147. Wiberg 2001, pp. 750, 975; Silberberg 2006, p. 314
148. Sidgwick 1950, p. 784; Moody 1991, pp. 248–9, 319
149. Russell & Lee 2005, p. 428
150. Eagleson 1994, p. 282
151. Russell & Lee 2005, p. 427
152. Sidgwick 1937, p. 181
153. Howe 1968, p. 62
154. Durrant & Durrant 1970, p. 790
155. Wiberg, Holleman & Wiberg 2001, p. 771; McQuarrie, Rock & Gallogly 2010, p. 111
156. Ropp 2012, p. 328
157. Miller, Lee & Choe 2002, p. 14; Aleandri & Bogdanović 2008, p. 326
158. Bobev & Sevov 2002
159. Xia & Bobev 2006
160. Bailar et al. 1984, p. 951
161. Hoffman 2004
162. Beamer & Maxwell 1946, pp.  1, 31
163. Russell & Lee 2005, p. 431
164. Halford 2006,p. 378
165. Legut, Friák & Šob 2010
166. Wiberg, Holleman & Wiberg 2001, pp. 594; Petrii 2012, p. 754
167. Bagnall 1966, p. 83
168. Bagnall 1966, pp. 42, 61; Wiberg, Holleman & Wiberg 2001, pp. 767–68
169. Schwietzer & Pesterfield pp. 241, 243
170. Bagnall 1962, p. 211
171. Wiberg, Holleman & Wiberg 2001, pp. 283, 595
172. Greenwood & Earnshaw 1998, p. 766
173. Bagnall 1966, p. 47
174. Emsley 2011, p. 58
175. Hermann, Hoffmann & Ashcroft 2013, p. 11604–1
176. Hawkes 2010; Holt, Rinehart & Wilson c. 2007; Hawkes 1999, p. 14; Roza 2009, p. 12
177. Harding, Johnson & Janes 2002, p. 61
178. Merinis, Legoux & Bouissières 1972; Kugler & Keller 1985, pp. 110, 116, 210–211, 224; Takahashi & Otozai 1986; Zuckerman & Hagen 1989, pp. 21–22 (21); Takahashi, Yano & Baba 1992
179. Russell & Lee 2005, p. 299
180. Eberle1985, pp. 190, 192,
181. Brown et al. 2012, p. 264
182. Wiberg 2001, p. 283
183. Eagleson 1994, p. 95
184. Pimpentel 1971, p. 827
185. Messler & Messler 2011, p. 38
186. Fine 1978, p. 718; Emsley 2011, p. 57
187. Thayer 2010, p. 79
188. Berei K & Vasáros 1985, p. 214
189. Pruszyński et al. 2006, pp. 91, 94
190. Zubieta & Zuckerman 2009, p. 260: 'The compounds AsSn and SbSn, which are classified as alloys of two B subgroup metals, exhibit superconducting properties with a transition temperature of about 4 K.'; Schwartz 2010, p. 32: 'The metals include the alkali and alkaline earths, beryllium, magnesium, copper, silver, gold and the transition metals. These metals exhibit those characteristics generally associated with the metallic state. The B subgroups comprise the remaining metallic elements. These elements exhibit complex structures and significant departures from typically metallic properties. Aluminum, although considered under the B subgroup metals, is somewhat anomalous as it exhibits many characteristics of a true metal.'
191. Greenwood & Earnshaw 1998, p. 548
192. Phillips & Williams 1965, pp. 4‒5; Steele 1966, p. 66
193. Phillips & Williams 1965, p. 33
194. Wiberg, Holleman & Wiberg 2001, pp. 1253, 1268
195. Steele 1966, p. 67
196. Parish 1977, pp. 201–202
197. Parish 1977, pp. 178
198. Rayner-Canham & Overton 2006, p. 29‒30
199. Pauling 1988, p. 173
200. Cardarelli 2008, p. 1181
201. Louis 1911, p. 11–12
202. Van Wert 1936, pp. 16, 18
203. Britton, Abbatiello & Robins 1972, p. 704
204. Sargent-Welch 2008
205. Hawkes 1997
206. Habashi 2010
207. Wiberg, Holleman & Wiberg 2001, p. 143
208. Klemm 1950
209. Miller GJ, Lee C & Choe W 2002, p. 22
210. Abrikosov 1988, p. 31
211. Cremer 1965, p. 514
212. Gray 2009, p. 9
213. Taylor et al. 2007, p. 148
214. Oxford English Dictionary 1989, 'other'
215. Roget's 21st Century Thesaurus
216. Gray 2010
217. Parish 1977, pp. 178, 189–190, 192–3
218. Slater 1939, p.&npsb;444‒445
219. Slater 1939, p. 448
220. Joshua 1991, p. 45
221. Farrell & Van Sicien 2007, p. 1442
222. Hill & Holman 2000, p. 40
223. Reid 2011, p. 143
224. Pashaey & Seleznev 1973, p. 565
225. Johansen & Mackintosh 1970, pp. 121–4; Divakar, Mohan & Singh 1984, p. 2337; Dávila et al. 2002, p. 035411-3
226. Jezequel & Thomas1997
227. Savitsky 1961, p. 107
228. Hindman 1968, p. 434: 'The high values obtained for the [electrical] resistivity indicate that the metallic properties of neptunium are closer to the semimetals than the true metals. This is also true for other metals in the actinide series.'; Dunlap et al. 1970, pp. 44, 46: '...α-Np is a semimetal, in which covalency effects are believed to also be of importance...For a semimetal having strong covalent bonding, like α-Np...'
229. Strathern 2000, p. 239
230. Roscoe & Schormlemmer 1894, p. 4
231. Murray 1809, p. 300
232. Young et al. 1969, p. 228
233. Cheronis, Parsons & Ronneberg 1942, p. 570

Indexed references

• Abd-El-Aziz AS, Carraher CE, Pittman CU, Sheats JE & Zeldin M 2003, Macromolecules Containing Metal and Metal-Like Elements, vol. 1, A Half-Century of Metal- and Metalloid-Containing Polymers, John Wiley & Sons, Hoboken, New Jersey, ISBN 0-471-45832-5
• Abrikosov AA 1988, Fundamentals of the theory of metals, North Holland, Amsterdam, ISBN 0-444-87094-6
• Aleandri LE & Bogdanović B 2008, 'The magnesium route to active metals and intermetallics, in A Fürstner (ed.), Active metals: Preparation, characterization, applications, VCH Verlagsgesellschalt, Weinheim, ISBN 3-527-29207-1, pp. 299‒338
• Alhassan SJ & Goodwin FE 2005, Lead and Alloys, in R Baboian (ed), 'Corrosion Tests and Standards: Application and Interpretation,' 2nd ed., ASTM International, West Conshohocken, PA, pp. 531–6, ISBN 0-8031-2098-2
• Arndt N & Ganino C 2012, Metals and Society: An Introduction to Economic Geology, Springer-Verlag, Berlin, ISBN 978-3-642-22995-4
• Atkins P, Overton T, Rourke J, Weller M & Armstrong F 2006, Shriver & Atkins inorganic chemistry, 4th ed., Oxford University Press, Oxford, ISBN 978-0-19-926463-6
• Atkins P & de Paula J 2011, Physical Chemistry for the Life Sciences, 2nd ed., Oxford University, Oxford, ISBN 978-0-19-956428-6
• Aylward G & Findlay T 2008, SI chemical data, 6th ed., John Wiley, Milton, Queensland, ISBN 978-0-470-81638-7
• Bagnall KW 1962, 'The chemistry of polonium,' in HHJ Emeleus & AG Sharpe (eds), Advances in inorganic chemistry and radiochemistry, vol. 4, Academic Press, New York, pp. 197‒230
• Bagnall KW 1966, The chemistry of selenium, tellurium and polonium, Elsevier, Amsterdam
• Bailar JC, Moeller T, Kleinberg J, Guss CO, Castellion ME & Metz C 1984, Chemistry, 2nd ed., Academic Press, Orlando, ISBN 0-12-072855-9
• Banthorpe DV, Gatford C & Hollebone BR 1968, 'Gas Chromatographic Separation of Olefins and Aromatic Hydrocarbons Using Thallium(I)-Nitrate: Glycol as Stationary Phase', Journal of Gas Chromatography, vol. 6, no. 1, pp.  61–62, doi:10.1093/chromsci/6.1.61
• Bashilova NI & Khomutova, TV 1984, 'Thallates of alkali metals and monovalent thallium formed in aqueous solutions of their hydroxides', Russian Chemical Bulletin, vol. 33, no. 8, August, pp. 1543–47
• Benbow EM 2008, From paramagnetism to spin glasses: Magnetic studies of single crystal intermetallics, PhD dissertation, Florida State University
• Berei K & Vasáros L 1985 'General aspects of the chemistry of astatine', pp. 183–209, in Kugler & Keller
• Bharara MS & Atwood, DA 2005, 'Lead: Inorganic chemistry', Encyclopedia of inorganic chemistry, RB King (ed.), 2nd ed., John Wiley & Sons, New York, ISBN 978-0-470-86078-6
• Beamer WH & Maxwell CR 1946, Physical properties and crystal structure of polonium, Los Alamos Scientific Laboratory, Oak Ridge, Tennessee
• Bobev S & Sevov SC 2002, 'Five ternary Zintl phases in the systems alkali-metal–indium–bismuth', Journal of Solid State Chemistry, vol. 163, no. 2, pp. 436–448, doi:10.1006/jssc.2001.9423
• Borsai, M 2005, 'Cadmium: Inorganic & coordination chemistry', in RB King (ed.), Encyclopedia of inorganic chemistry, 2nd ed., vol. 2, John Wiley & Sons, New York, pp. 603–19, ISBN 978-0-470-86078-6
• Braunović M 2000, 'Power Connectors', in PG Slade (ed.), Electrical Contacts: Principles and Applications, 2nd ed., CRC Press, Boca Raton, Florida, pp. 231–374, ISBN 978-1-4398-8130-9
• Britton RB, Abbatiello FJ & Robins KE 1972, 'Flux pumps and superconducting components, in Y Winterbottom (ed.), Proceedings of the 4th International Conference on Magnetic Technology, 19‒22 September 1972, Upton, New York, Atomic Energy Commission, Washington DC, pp. 703‒708
• Brown TE, LeMay HE, Bursten BE, Woodward P & Murphy C 2012, Chemistry: The Central Science, 12th ed., Pearson Education, Glenview, Illinois, ISBN 978-0-321-69672-4
• Busev, AI 1962, The analytical chemistry of indium, Pergamon, Oxford
• Cardarelli F 2008, Materials handbook: A concise desktop reference, 2nd ed., Springer-Verlag, Berlin, ISBN 978-1-84628-669-8
• Chambers C & Holliday AK 1975, Modern inorganic chemistry: An intermediate text, Butterworths, London, ISBN 0-408-70663-5
• Chandler H 1998, Metallurgy for the non-metallurgist, ASM International, Materials Park, Ohio, ISBN 0-87170-652-0
• Charles JA, Crane FAA & Furness JAG 1997, Selection and use of Engineering Materials, 3rd ed., Butterworth-Heinemann, Oxford, ISBN 0-7506-3277-1
• Cheemalapati K, Keleher J & Li Y 2008 'Key chemical components in metal CMP slurries', in Y Li (ed.), Microelectronic Applications of Chemical Mechanical Planarization, John Wiley & Sons, Hoboken, New Jersey, pp. 201–248, ISBN 0-471-71919-6
• Cheronis ND, Parsons JB & Ronneberg CE 1942, The study of the physical world, Houghton Mifflin Company, Boston
• Clegg AG & Dovaston NG 2003, 'Conductors and superconductors', in MA Laughton & DF Warne, Electrical engineer's reference book, 16th ed., Elsevier Science, Oxford, pp. 5/1–13, ISBN 0-7506-4637-3
• Cobb F 2009, Structural engineer's pocket book, 2nd ed., Elsevier, Oxford, ISBN 978-0-7506-8686-0
• Collings EW 1986, Applied Superconductivity, Metallurgy, and Physics of Titanium alloys, vol. 1, Plenum Press, New York, ISBN 0-306-41690-5
• Cooney RPJ & Hall JR 1966, 'Raman spectrum of thiomercurate(II) ion,' Australian Journal of Chemistry, vol. 19, pp. 2179–2180
• Cooper DG 1968, The periodic table, 4th ed., Butterworths, London
• Corbett JD 1996, 'Zintl phases of the early p-block elements', in SM Kauzlarich (ed.), Chemistry, structure and bonding of Zintl phases and ions, VCH, New York, ISBN 1-56081-900-6, pp. 139‒182
• Cotton FA, Wilkinson G, Murillo CA & Bochmann M 1999, Advanced inorganic chemistry, 6th ed., John Wiley & Sons, New York, ISBN 978-0-471-19957-1
• Cox PA 2004, Inorganic chemistry, 2nd ed., Instant notes series, Bios Scientific, London, ISBN 1-85996-289-0
• Cramer SD & Covino BS 2006, Corrosion: environments and industries, ASM Handbook, vol. 13C, ASM International, Metals Park, Ohio, ISBN 0-87170-709-8
• Cremer HW, Davies TR, Watkins SB 1965, Chemical Engineering Practice, vol. 8, 'Chemical kinetics,' Butterworths Scientific Publications, London
• Crichton R 2012, Biological inorganic chemistry: A new introduction to molecular structure and function, 2nd ed., Elsevier, Amsterdam, ISBN 978-0-444-53782-9
• Darriet B, Devalette M & Lecart B 1977, 'Determination de la structure cristalline de K₃AgO₂', Revue de chimie minérale, vol. 14, no. 5, pp. 423–428
• Dennis JK & Such TE 1993, Nickel and chromium plating, 3rd ed, Woodhead Publishing, Abington, Cambridge, ISBN 1-85573-081-2
• Darken L & Gurry R 1953, Physical chemistry of metals, international student edition, McGraw-Hill Book Company, New York
• Dávila ME, Molotov SL, Laubschat C & Asensio MC 2002, 'Structural determination of Yb single-crystal films grown on W(110) using photoelectron diffraction', Physical Review B, vol. 66, no. 3, p. 035411–18, doi:10.1103/PhysRevB.66.035411
• Davis JR (ed.) 1999, 'Galvanic, deposition, and stray-current deposition', Corrosion of aluminum and aluminum alloys, ASM International, Metals Park, Ohio, pp. 75–84, ISBN 0-87170-629-6
• Deiseroth H-J 2008, 'Discrete and extended metal clusters in alloys with mercury and other Group 12 elements', in M Driess & H Nöth (eds), Molecular clusters of the main group elements, Wiley-VCH, Chichester, pp. 169‒187, ISBN 978-3-527-61437-0
• Deming HG 1940, Fundamental Chemistry, John Wiley & Sons, New York
• Dillard CR & Goldberg DE 1971, Chemistry: Reactions, Structure, and Properties, Macmillan, New York
• Dirkse, TP (ed.) 1986, Copper, silver, gold and zinc, cadmium, mercury oxides and hydroxides, IUPAC solubility data series, vol. 23, Pergamon, Oxford, ISBN 0-08-032497-5
• Divakar C, Mohan M & Singh AK 1984, 'The kinetics of pressure-induced fcc-bcc transformation in ytterbium', Journal of Applied Physics, vol. 56, no. 8, pp. 2337–40, doi:10.1063/1.334270
• Donohue J 1982, The structures of the elements, Robert E. Krieger, Malabar, Florida, ISBN 0-89874-230-7
• Driess M & Nöth H 2004, Molecular clusters of the main group elements, Wiley-VCH, Weinheim
• Dunlap BD, Brodsky MB, Shenoy GK & Kalvius GM 1970, 'Hyperfine interactions and anisotropic lattice vibrations of ²³⁷Np in α-Np metal', Physical Review B, vol. 1, no. 1, pp. 44–49, doi:10.1103/PhysRevB.1.44
• Durrant PJ & Durrant B 1970, Introduction to advanced inorganic chemistry, 2nd ed., Longman
• Dwight J 1999, Aluminium design and construction, E & FN Spon, London, ISBN 0-419-15710-7
• Eagleson M 1994, Concise encyclopedia chemistry, Walter de Gruyter, Berlin, ISBN 3-11-011451-8
• Eason R 2007, Pulsed laser deposition of thin films: applications-led growth of functional materials, Wiley-Interscience, New York
• Eberle SH 1985, 'Chemical Behavior and Compounds of Astatine', pp. 183–209, in Kugler & Keller
• Emsley J 2011, Nature's Building Blocks: An A–Z guide to the Elements], new edition, Oxford University Press, Oxford, ISBN 978-0-19-960563-7
• Eranna G 2012, Metal oxide nanostructures as gas sensing devices, CRC Press, Boca Raton, Florida, ISBN 978-1-4398-6340-4
• Evans RC 1966, An introduction to crystal chemistry, 2nd (corrected) edition, Cambridge University Press, London
• Evers J 2011, 'High pressure investigations on A^IB^III Zintl compounds (A^I = Li to Cs; B^III = Al to Tl) up to 30 GPa', in TF Fässler (ed.), Zintl phases: Principles and recent developments, Springer-Verlag, Berlin, pp. 57‒96, ISBN 978-3-642-21150-8
• Farrell HH & Van Sicien CD 2007, 'Binding energy, vapor pressure, and melting point of semiconductor nanoparticles', Journal of Vacuum Science Technology B, vol. 25, no. 4, pp. 1441–47, doi:10.1116/1.2748415
• Fine LW 1978, Chemistry, 2nd ed., The Wilkins & Wilkins Company. Baltimore, ISBN 0-683-03210-0
• Fishcher-Bünher J 2010, 'Metallurgy of Gold' in C Corti & R Holliday (eds), Gold: Science and Applications, CRC Press, Boca Raton, pp. 123–160, ISBN 978-1-4200-6523-7
• Geffner SL 1969, 'Teaching the transition elements', letter, Journal of Chemical Education, vol. 46, no. 5, p. 329, doi:10.1021/ed046p329.4
• Gerard G & King WR 1968, 'Aluminum', in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold, New York
• Gladyshev VP & Kovaleva SV 1998, 'Liquidus shape of the mercury–gallium system', Russian Journal of Inorganic Chemistry, vol. 43, no. 9, pp. 1445–
• Glaeser WA 1992, Materials for tribology, Elsevier Science, Amsterdam, ISBN 0-444-88495-5
• Goffer Z 2007, Archaeological Chemistry, 2nd ed., John Wiley & Sons, Hoboken, New Jersey, ISBN 978-0-471-25288-7
• Goodwin F, Guruswamy S, Kainer KU, Kammer C, Knabl W, Koethe A, Leichtfreid G, Schlamp G, Stickler R & Warlimont H 2005, 'Noble metals and noble metal alloys', in Springer Handbook of Condensed Matter and Materials Data, W Martienssen & H Warlimont (eds), Springer, Berlin, pp. 329–406, ISBN 3-540-44376-2
• Gray T 2009, The elements: A visual exploration of every known atom in the universe, Black Dog & Leventhal, New York, ISBN 978-1-57912-814-2
• Gray T 2010, 'Other Metals (11)', viewed 27 September 2013
• Greenwood NN & Earnshaw A 1998, Chemistry of the elements, 2nd ed., Butterworth-Heinemann, ISBN 0-7506-3365-4
• Gupta CK 2002, Chemical metallurgy: Principles and practice, Wiley-VCH, Weinheim, ISBN 3-527-30376-6
• Gupta U 2010, Design and characterization of post-transition, main-group, heteroatomic clusters using mass spectrometry, anion photoelectron spectroscopy and velocity map imaging, PhD dissertation, Pennsylvania State University
• Habashi F 2010, 'Metals: Typical and less typical, transition and less typical', Foundations of Chenistry, vol. 12, pp. 31–39, doi:10.1007s10698-009-9069-6
• Halford GR 2006, Fatigue and durability of structural materials, ASM International, Materials Park, Ohio, ISBN 0-87170-825-6
• Haller EE 2006, 'Germanium: From its Discovery to SiGe Devices', Materials Science in Semiconductor Processing, vol. 9, nos 4–5, doi:10.1016/j.mssp.2006.08.063, viewed 8 February 2013
• Harding C, Johnson DA & Janes R 2002, Elements of the p Block, Royal Society of Chemistry, Cambridge, ISBN 0-85404-690-9
• Häussermann U 2008, 'Coexistence of hydrogen and polyanions in multinary main group element hydrides', Zeitschrift für Kristallographie - Crystalline Materials, vol. 223, no. 10, pp. 628–635, doi:10.1524/zkri.2008.1016
• Hawkes SJ 1997, 'What is a "Heavy Metal"?', Journal of Chemical Education, vol. 74, no. 11, p, 1374, doi:10.1021/ed074p1374
• Hawkes SJ 1999, 'Polonium and Astatine are not Semimetals', Chem 13 News, February, p. 14, ISSN 0703-1157
• Hawkes SJ 2010, 'Polonium and Astatine are not Semimetals', Journal of Chemical Education, vol. 87, no. 8, p. 783, doi:10.1021ed100308w
• Henderson M 2000, Main group chemistry, The Royal Society of Chemistry, Cambridge, ISBN 0-85404-617-8
• Hermann A, Hoffmann R & Ashcroft NW 2013, 'Condensed Astatine: Monatomic and Metallic', Physical Review Letters, vol. 111, pp. 11604–1−11604-5, doi:10.1103/PhysRevLett.111.116404
• Hill G & Holman J 2000, Chemistry in context, 5th ed., Nelson Thornes, Cheltenham, ISBN 0-17-448307-4
• Hindman JC 1968, 'Neptunium', in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold, New York, pp. 432–7
• Hinton H & Dobrota N 1978, 'Density gradient centrifugation', in TS Work & E Work (eds), Laboratory techniques in biochemistry and molecular biology, vol. 6, Elsevier/North-Holland Biomedical Press, Amsterdam, pp. 1–290, ISBN 0-7204-4200-1
• Hoffman P 2004, Semimetal surfaces, viewed 17 September 2013.
• Holl HA 1989, 'Materials for warship applications – past, present and future', in R Bufton & P Yakimiuk (eds), Past, present and future engineering in the Royal Navy, the Institute of Marine Engineers centenary year conference proceedings, RNEC Manadon, Plymouth, 6‒8 September 1989, Marine Management (Holdings) for the Institute of Marine Engineers, London, pp. 87–96, ISBN 0-907206-28-X
• Holman J & Stone P 2001, Chemistry, 2nd ed., Nelson Thornes, Walton on Thames, ISBN 0-7487-6239-6
• Holt, Rinehart & Wilson c. 2007 'Why Polonium and Astatine are not Metalloids in HRW texts', viewed 14 October 2014
• Howe, HE 1968, 'Bismuth' in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold, New York, pp. 56–65
• Howe, HE 1968a, 'Thallium' in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold, New York, pp. 706–711
• Huheey JE & Huheey CL 1972, 'Anomalous properties of elements that follow "long periods" of elements', Journal of Chemical Education, vol. 49, no. 4, pp. 227–230, doi:10.1021/ed049p227
• Huheey JE, Keiter EA & Keiter RL 1993, Principles of Structure & Reactivity, 4th ed., HarperCollins College Publishers, ISBN 0-06-042995-X
• Hurd MK 1965, Formwork for concrete, 7th ed, American Concrete Institute, Farmington Hills, Michigan, ISBN 0-87031-177-8
• Hutchinson E 1964, Chemistry: The elements and their reactions, 2nd ed., W B Saunders Company, Philadelphia
• IUPAC 2005, Nomenclature of inorganic chemistry (the "Red Book"), NG Connelly & T Damhus eds, RSC Publishing, Cambridge, ISBN 0-85404-438-8
• IUPAC 2006–, Compendium of chemical terminology (the "Gold Book"), 2nd ed., by M Nic, J Jirat & B Kosata, with updates compiled by A Jenkins, ISBN 0-9678550-9-8, doi:10.1351/goldbook
• Ivanov-Emin BN, Nisel'son LA & Greksa, Y 1960, 'Solubility of indium hydroxide in solution of sodium hydroxide', Russian Journal of Inorganic Chemistry, vol. 5, pp. 1996–8, in WC Sheets, E Mugnier, A Barnabé, TJ Marks & KR Poeppelmeier 2006, 'Hydrothermal synthesis of delafossite-type oxides', Chemistry of Materials, vol. 18, pp. 7–20 (15), doi:10.1021/cm051791c
• Jensen WB 2003, 'The place of zinc, cadmium and mercury in the periodic table,' Journal of Chemical Education, vol. 80, no. 8, pp. 952‒61, doi:10.1021/ed080p952
• Jensen WB 2008, 'Is mercury now a transition element?', Journal of Chemical Education, vol. 85, no. 9, pp. 1182‒1183, doi:10.1021/ed085p1182
• Jezequel G & Thomas J 1997, 'Experimental band structure of semimetal bismuth', Physical Review B, vol. 56, no. 11, pp. 6620–6, doi:10.1103/PhysRevB.56.6620
• Johansen G & Mackintosh AR 1970, 'Electronic structure and phase transitions in ytterbium', Solid State Communications, vol. 8, no. 2, pp. 121–4
• Johnson O 1970, 'Role of f electrons in chemical binding", Journal of Chemical Education, vol. 47, no. 6, pp. 431–2, doi:10.1021/ed047p431
• Joshua SJ 1991, Symmetry principles and magnetic symmetry in solid state physics, Andrew Hilger, Bristol, ISBN 0-7503-0070-1
• Kauzlarich SM 2005, 'Zintl compounds' in RB King (ed.), Encyclopedia of inorganic chemistry, vol. 8, John Wiley & Sons, Chichester, pp. 6006–14, ISBN 978-0-470-86078-6
• Kauzlarich SM, Payne AC & Webb DJ 2002, 'Magnetism and magnetotransport properties of transition metal zintl isotypes', in JS Miller & M Drillon (eds), Magnetism: Molecules to Materials III, Wiley-VCH, Weinheim, pp. 37–62, ISBN 3-527-30302-2
• Kent A 1993, Experimental low temperature physics, American Institute of Physics, New York, ISBN 1-56396-030-3
• King RB 1995, Chemistry of the main group elements, VCH Publishers, New York, ISBN 1-56081-679-1
• King RB 2004, 'The metallurgist’s periodic table and the Zintl-Klemm concept', in DH Rouvray DH & RB King (eds), The periodic table: into the 21st century, Institute of Physics Publishing, Philadelphia, ISBN 978-0-86380-292-8, pp. 189–206.
• King RB & Schleyer R 2004, 'Theory and concepts in main-group cluster chemistry', in M Driess and H Nöth (eds), Molecular clusters of the main group elements, Wiley-VCH, Chichester, pp. 1–33, ISBN 978-3-527-61437-0
• Klassen H & Hoppe R 1982, 'Alkalioxoargentate(I). Über Na₃AgO₂', Zeitschrift für anorganische und allgemeine Chemie, vol. 485, no. 1, pp. 92–100, doi:10.1002/zaac.19824850109
• Klemm W 1950, 'Einige probleme aus der physik und der chemie der halbmetalle und der metametalle', Angewandte Chemie, vol. 62, no. 6, pp. 133–42
• Kneen WR, Rogers MJW & Simpson P 1972, Chemistry: Facts, Patterns, and Principles, Addison-Wesley, London, ISBN 0-201-03779-3
• Kneip R 1996, 'Eduard Zintl: His life and scholarly work' in SM Kauzlarich (ed.), Chemistry, structure and bonding of zintl phases and ions, VCH, New York, pp. xvi–xxx, ISBN 1-56081-900-6
• Köhler J & Whangbo M-H 2008, 'Electronic Structure Study of the [Ag−Ag]⁴⁻, [Au−Au]⁴⁻, and [Hg−Hg]²⁻ Zintl Anions in the Intermetallic Compounds Yb₃Ag₂, Ca₅Au₄, and Ca₃Hg₂: Transition Metal Anions As p-Metal Elements', Chemistry of Materials, vol. 20, no. 8, pp. 2751–2756, doi:10.1021/cm703590d
• Kugler HK & Keller C (eds) 1985, Gmelin Handbook of Inorganic and Organometallic chemistry, 8th ed., 'At, Astatine', system no. 8a, Springer-Verlag, Berlin, ISBN 3-540-93516-9
• Larson P, Mahanti SD, Salvador J & Kanatzidis MG 2006, 'Electronic Structure of the Ternary Zintl-phase Compounds Zr3Ni3Sb4, Hf3Ni3Sb4, and Zr3Pt3Sb4 and Their Similarity to Half-Heusler Compounds Such as ZrNiSn', Physical Review B, vol. 74, pp. 035111–1–035111-8
• Legut D, Friák M & Šob M 2010, 'Phase stability, elasticity, and theoretical strength of polonium from first principles,' Physical Review B, vol. 81, pp. 214118–1 to 19, doi:10.1103/PhysRevB.81.214118
• Leman JT & Barron AR 2005, 'Indium: Inorganic chemistry', Encyclopedia of Inorganic Chemistry, RB King (ed.), 2nd ed., Wiley, pp. 1526–1531
• Liang SC, King RA & White CET 1968, 'Indium', in CA Hampel (ed.), The encyclopedia of the chemical elements, Reinhold, New York, pp. 283–290
• Lidin RA 1996, Inorganic substances handbook, begell house, New York, ISBN 1-56700-065-7
• Liptrot FJ 2001, 'Overhead lines', in HM Ryan (ed.), High voltage electrical engineering and testing, 2nd ed., The Institute of Electrical Engineers, London, pp. 167‒211, ISBN 0-85296-775-6
• Lister, T 1998, Industrial chemistry case studies: Industrial processes in the 1990s, The Royal Society of Chemistry, London, ISBN 0-85404-925-8
• Liu H, Knowles CR & Chang LLY 1995, 'Extent of solid solution in Pb-Sn and Sb-Bi chalcogenides', The Canadian Mineralogist, vol.33, pp. 115–128
• Louis H 1911, Metallurgy of tin, McGraw-Hill Book Company, New York
• Lyons A 2007, Materials for architects & builders, 3rd ed., Elsevier, Oxford, ISBN 978-0-7506-6940-5
• Mackay KM & Mackay RA 1989, Introduction to modern inorganic chemistry, 4th ed., Blackie, Glasgow, ISBN 0-7487-6420-8
• Mason J 1988, 'Periodic contractions among the elements: Or, on being the right size', Journal of Chemical Education, vol. 65, no. 1, pp. 17–20, doi:10.1021/ed065p17
• Massalski TB (ed.) 1986, Noble metal alloys: phase diagrams, alloy phase stability, thermodynamic aspects, properties and special features, proceedings of the TMS Alloy Phase Committee, the TMS Thermodynamics Committee, and the American Society for Metals Alloy Phase Diagram Data Committee, held at the Metallurgical Society of AIME Annual Meeting, February 24‒28, 1985, The Society, Warrendale, Portland, ISBN 978-0-87339-011-8
• Massey AG 2000, Main group chemistry, 2nd ed, John Wiley & Sons, Chichester, ISBN 0-471-49037-7
• Masterton W, Hurley C & Neth E 2011, Chemistry: Principles and Reactions, 7th ed., Brooks/Cole, Belmont, California, ISBN 1-111-42710-0
• McQuarrie DA, Rock PA & Gallogly EB 2010, 'Interchapter 1: The main group metals', General chemistry, 4th ed., University Science Books, Mill Valley, California, ISBN 978-1-891389-60-3
• Merinis J, Legoux G & Bouissières G 1972, "Etude de la formation en phase gazeuse de composés interhalogénés d'astate par thermochromatographie" [Study of the gas-phase formation of interhalogen compounds of astatine by thermochromatography], Radiochemical and Radioanalytical Letters (in French), vol. 11, no. 1, pp. 59–64
• Messler RW 2011, Integral mechanical attachment: A resurgence of the oldest method of joining, Elsevier, Burlington, Massachusetts, ISBN 978-0-7506-7965-7
• Messler RW & Messler RW Jr 2011, The Essence of Materials for Engineers, Jones & Bartlett Learning, Sudbury, Massachusetts, ISBN 0-7637-7833-8
• Miller GJ, Lee C & Choe W 2002, 'Structure and bonding around the Zintl border', in G Meyer, D Naumann & L Wesermann (eds), Inorganic chemistry highlights, Wiley-VCH, Weinheim, pp. 21–53, ISBN 3-527-30265-4
• Miller GJ, Schmidt MW, Wang F & You T-S 2011, 'Quantitative Advances in the Zintl-Klemm Formalism,' in TF Fässler (ed), Zintl Phases: Principles and Recent Developments, Springer-Verlag, Berlin, pp. 1 56, ISBN 978-3-642-21149-2
• Mittemeijer EJ 2010, Fundamentals of materials science: The microstructure–property relationship using metals as model systems, Springer-Verlag, Berlin, ISBN 978-3-642-10499-2
• Moeller T 1952, Inorganic chemistry: An advanced textbook, John Wiley & Sons, New York
• Moody B 1991, Comparative Inorganic Chemistry, 3rd ed., Edward Arnold, London, ISBN 0-7131-3679-0
• Müller M 1992, Inorganic structural chemistry, 2nd ed., John Wiley & Sons, Chichester, ISBN 0-471-93717-7
• Murray J 1809, A system of chemistry, 2nd ed., vol. 3, Longman, Hurst, Rees and Orme; and John Murray, London
• Noble IG 1985, 'Structural fire protection of cargo ships and guidance on the requirements of the Merchant Shipping (Fire Protection) Regulations 1984', discussion, in Ship fires in the 1980s, Tuesday 3 and Wednesday 4 December 1985 at the Institute of Marine Engineers, pp. 20–22, Marine Management (Holdings), London, c1986, ISBN 0-907206-15-8
• Norman NC 1997, Periodicity and the s- and p-block elements, Oxford University, Oxford, ISBN 0-19-855961-5
• Ogata S, Li J & Yip S 2002, 'Ideal pure shear strength of aluminium and copper', Science, vol. 298, no. 5594, 25 October, pp. 807–10, doi:10.1126/science.1076652
• Oxford English Dictionary 1989, 2nd ed., Oxford University, Oxford, ISBN 0-19-861213-3
• Parish RV 1977, The metallic elements, Longman, London, ISBN 0-582-44278-8
• Pashaey BP & Seleznev VV 1973, 'Magnetic susceptibility of gallium-indium alloys in liquid state', Russian Physics Journal, vol. 16, no. 4, pp. 565–6, doi:10.1007/BF00890855
• Patnaik, P 2003, Handbook of inorganic chemicals, McGraw-Hill, New York, ISBN 978-0-07-049439-8
• Pauling L 1988, General chemistry, Dover Publications, New York, ISBN 0-486-65622-5
• Petrii OA 2012, 'Chemistry, electrochemistry and electrochemical applications', in J Garche, C Dyer, P Moseley, Z Ogumi, D Rand & B Scrosati (eds), Encyclopedia of electrochemica power sources, Elsevier B.V., Amsterdam, ISBN 978-0-444-52093-7
• Phillips CSG & Williams RJP 1965, Inorganic chemistry, II: Metals, Clarendon Press, Oxford
• Pimpentel GC & Spratley RD 1971, Understanding chemistry, Holden-Day, San Francisco
• Polmear I 2006, Light alloys: From traditional alloys to nanocrystals, 4th ed., Elsevier, Oxford, ISBN 0-7506-6371-5
• Poole CP 2004, Encyclopedic dictionary of condensed matter physics, vol. 1 A–M, trans. from Translated from the original Russian ed., published National Academy of Sciences of Ukraine, 1996–1998, Elsevier, Amsterdam, ISBN 0-12-088398-8
• Pruszyński M, Bilewicz A, Wąs B & Petelenz B 2006, 'Formation and stability of astatide-mercury complexes', Journal of Radioanalytical and Nuclear Chemistry, vol. 268, no. 1, pp. 91–94, doi:10.1007/s10967-006-0129-2
• Ramroth WT 2006, Thermo-mechanical structural modelling of FRP composite sandwich panels exposed to fire, PhD thesis, University of California, San Diego, ISBN 978-0-542-85617-4
• Rankin WJ 2011, Minerals, metals and sustainability: Meeting future material needs, CSIRO Publishing, Collingwood, ISBN 978-0-643-09726-1
• Rayner-Canham G & Overton T 2006, Descriptive inorganic chemistry, 4th ed., WH Freeman, New York, ISBN 0-7167-8963-9
• Reid D, Groves G, Price C & Tennant I 2011, Science for the New Zealand curriculum Year 11, Cambridge University, Cambridge, ISBN 978-0-521-18618-6
• Roget's 21st Century Thesaurus, 3rd ed, Philip Lief Group
• Roher GS 2001, Structure and bonding in crystalline materials, Cambridge University Press, Cambridge, ISBN 0-521-66379-2
• Ropp RC 2012, Encyclopedia of the alkaline earth compounds, Elsevier, Oxford, ISBN 978-0-444-59550-8
• Roscoe HE & Schorlemmer FRS 1894, A treatise on chemistry: Volume II: The metals, D Appleton, New York
• Roza G 2009, Bromine, Rosen Publishing, New York, ISBN 1-4358-5068-8
• Russell AM & Lee KL 2005, Structure-property relations in nonferrous metals, Wiley-Interscience, New York, ISBN 0-471-64952-X
• Ryan W (ed.) 1968, Non-ferrous Extractive Metallurgy in the United Kingdom, Institution of Mining and Metallurgy, London
• Samsonov GV 1968, Handbook of the physiochemical properties of the elements, I F I/Plenum, New York
• Sargent-Welch VWR International 2008, Chart of the elements: With electron distribution, Buffalo Grove, Illinois
• Savitsky EM 1961, The influence of temperature on the mechanical properties of metals and alloys, Stanford University Press, Stanford
• Sazhin NP 1961, 'Development of the metallurgy of the rare and minor metals in the USSR,' in IP Bardin (ed.), Metallurgy of the USSR, 1917-1957, volume 1, originally published by Metallurgizdat, State Scientific and Technical Publishing House of Literature on Ferrous and Nonferrous Metallurgy, Moscow, 1958; published for the National Science Foundation, Washington, DC and the Department of the Interior, USA by the Israel Program for Scientific Translations, Jerusalem, p.p. 744–64
• Schumann W 2008, Minerals of the World, 2nd ed., trans. by EE Reinersman, Sterling Publishing, New York, ISBN 978-1-4027-5339-8
• Schwartz M 2010, Encyclopedia and handbook of materials, parts and finishes, 2nd ed., CRC Press, Boca Raton, Florida, ISBN 1-56676-661-3
• Schweitzer PA 2003, Metallic materials: Physical, mechanical, and corrosion properties, Marcel Dekker, New York, ISBN 0-8247-0878-4
• Schwietzer GK & Pesterfield LL 2010, The aqueous chemistry of the elements, Oxford University, Oxford, ISBN 0-19-539335-X
• Science Education 1948, Deming, Horace G. Fundamental Chemistry. New York: John Wiley and Sons, Inc., 1947. 745 p. $4.00, book review, vol. 32, no. 2, doi:10.1002/sce.3730320231
• Scott EC & Kanda FA 1962, The nature of atoms and molecules: A general chemistry, Harper & Row, New York
• Sequeira CAC 2013, 'Diffusion coatings for the oil industry', in R Javaherdashti, C Nwaoha, H Tan (eds), Corrosion and materials in the oil and gas industries, RC Press, Boca Raton
• Sevov SC, Ostenson JE & Corbett JD 1993, 'K₈In₁₀Hg: a Zintl phase with isolated In₁₀Hg clusters', Journal of Alloys and Compounds, vol. 202, nos. 1‒2, pp. 289–294, doi:10.1016/0925-8388(93)90551-W
• Sidgwick NV 1937, The electronic theory of valence, Oxford University Press, London
• Sidgwick NV 1950, The Chemical Elements and Their Compounds: Volume I, Clarendon Press, Oxford
• Silberberg MS 2006, Chemistry: The Molecular Nature of Matter and Change, 4th ed., McGraw-Hill, New York, ISBN 0-07-111658-3
• Slabon A, Budnyk S, Cuervo-Reyes E, Wörle M, Mensing C & Nesper R 2012, 'Copper Silicides with the Highest Lithium Content: Li₇CuSi₂ Containing the 16-Electron Group [CuSi₂]⁷⁻ and Li_7.3CuSi₃ with Heterographene Nets2
  ∞[CuSi]^3.3−', Angewandte Chemie International Edition,, vol. 51, no. 46, pp. 11594–11596, doi:10.1002/anie.201203504
• Slater JC 1939, Introduction to chemical physics, McGraw-Hill Book Company, New York
• Smith DW 1990, Inorganic substances: A prelude to the study of descriptive inorganic chemistry, Cambridge University, Cambridge, ISBN 0-521-33738-0
• Sofin M, Fiese K, Nuss J, Peters EM & Jansen M 2002, 'Synthesis and Crystal Structure of Rb₃AgO₂', Zeitschrift für anorganische und allgemeine Chemie, vol. 628. no. 11, pp. 2500–4,doi:10.1002/1521-3749(200211)628:11<2500::AID-ZAAC2500>3.0.CO;2-L
• Solov'eva VD, Svirchevskaya EG, Bobrova VV & El'tsov NM 1973, 'Solubility of copper, cadmium, and indium oxides in sodium hydroxide solutions', Trudy Instittua Metallurgii i Obogashcheniya, Akademiya Nauk Kazakhskoi SSR (Transactions of the Institute of Metallurgy and Ore Dressing, Academy of Sciences of the Kazakh SSR) vol. 49, pp. 37–44
• Sorensen EMB 1991, Metal poisoning in fish, CRC Press, Boca Raton, Florida, ISBN 0-8493-4268-6
• Steele D 1966, The chemistry of the metallic elements, Pergamon Press, Oxford
• Steiner LE & Campbell JA 1955, General Chemistry, The Macmillan Company, New York
• Steiner LE & Campbell JA 1955, General Chemistry, The Macmillan Company, New York
• Strathern P 2000, Mendeleyev's dream: The quest for the elements, Hamish Hamilton, London, ISBN 0-241-14065-X
• Subba Rao GV & Shafer MW 1986, 'Intercalation in layered transition metal dichalcogenides', in F Lévy (ed), Intercalated Layered Materials, D Reidel, Dordrecht, ISBN 90-277-0967-X, pp. 99–200
• Takahashi N & Otozai K 1986, "The mechanism of the reaction of elementary astatine with organic solvents", Journal of Radioanalytical and Nuclear Chemistry, vol. 103, no. 1, pp. 1‒9, doi:10.1007/BF02165358
• Takahashi N, Yano D & Baba H 1992, "Chemical behavior of astatine molecules", Proceedings of the international conference on evolution in beam applications, Takasaki, Japan, November 5‒8, 1991, pp. 536‒539
• Taylor MJ & Brothers PJ 1993, 'Inorganic derivatives of the elements', in AJ Downs (ed.), Chemistry of aluminium, gallium, indium and thallium, Chapman & Hall, London, ISBN 0-7514-0103-X
• Taylor N, Derbogosian M, Ng W, Stubbs A, Stokes R, Bowen S, Raphael S & Moloney J 2007, Study on chemistry 1, John Wiley & Sons, Milton, Queensland, ISBN 978-0-7314-0418-6
• Temkin ON 2012, Homogeneous Catalysis with Metal Complexes: Kinetic Aspects and Mechanisms, John Wiley & Sons, Chichester, ISBN 978-0-470-66699-9
• Thayer JS 2010, 'Relativistic effects and the chemistry of the heavier main-group elements,' in Relativistic methods for chemists, M Barysz & Y Ishikawa (eds), pp. 63–98, Springer Science+Business Media B. V., Dordrecht, ISBN 978-1-4020-9974-8
• Tóth I & Győri B 2005, 'Thallium: Inorganic chemistry', Encyclopedia of Inorganic Chemistry, RB King (ed.), 2nd ed., John Wiley & Sons, New York, ISBN 0-471-93620-0 (set)
• US Department of Transportation, Maritime Administration 1987, Marine fire prevention, firefighting and fire safety, Washington DC
• Vanderah TA 1992, Chemistry of Superconductor Materials: Preparation, Chemistry, Characterization, and Theory, Noyes Publications, New Jersey, ISBN 0-8155-1279-1
• Van Wert LR 1936, An introduction to physical metallurgy, McGraw-Hill Book Company, New York
• Vargel C 2004, Corrosion of aluminium, Elsevier, Amsterdam, ISBN 0-08-044495-4
• Walker JD, Enache M & Newman MC 2013, Fundamental QSARS for metal ions, CRC Press, Boca Raton, Florida, ISBN 978-1-4200-8433-7
• Wanamaker E & Pennington HR 1921, Electric arc welding, Simmons-Boardman, New York
• Wells AF 1985, Structural inorganic chemistry, 5th ed., Clarendon, Oxford, ISBN 0-19-855370-6
• Whitten KW, Davis RE, Peck LM & Stanley GG 2014, Chemistry, 10th ed., Thomson Brooks/Cole, Belmont, California, ISBN 1-133-61066-8
• Wiberg N 2001, Inorganic chemistry, Academic Press, San Diego, ISBN 0-12-352651-5
• Xia S & Bobev S 2006, 'Ba₁₁Cd₈Bi₁₄: Bismuth zigzag chains in a ternary alkaline-earth transition-metal Zintl phase', Inorganic Chemistry, vol. 45, no. 18, pp. 7126–7132, doi:10.1021/ic060583z
• Young JA, Malik JG, Quagliano JV & Danehy JP 1969, 'Chemical queries. Especially for introductory chemistry teachers: Do elements in the zinc subgroup belong to the transition series?', Journal of Chemical Education, vol. 46, no. 4, pp. 227‒229 (228), doi:10.1021/ed046p227
• Zubieta JA & Zuckerman JJ 2009, 'Structural tin chemistry', in SJ Lippard (ed.), Progress in inorganic chemistry, vol. 24, pp. 251–476 (260), ISBN 978-0-470-16675-8
• Zuckerman JJ & Hagen AP 1989, Inorganic Reactions and Methods, the Formation of Bonds to Halogens, John Wiley & Sons, New York, ISBN 978-0-471-18656-4