الفلزات الضعيفة أوالفلزات تحت الإنتنطقية العناصر الفلزية هي فلزات المستوى الفرعى p ، وتقع بين أشباه الفلزات والفلزات الإنتنطقية. وهى موجبة كهربيا أكثر من الفلزات الإنتنطقية ، ولكن أقل من الفلزات القلوية والفلزات القلوية الترابية . ودرجات الذوبان والغليان بصفة عامة أقل من الفلزات الإنتنطقية، كما أنها أيضا أقل صلابة.

الفلزات الضعيفة هي: ألومنيوم ، جاليوم ،إنديوم، قصدير، ثاليوم، رصاص، بزموث . العناصر من 113 إلى 116 تم وضعها ضمن هذه المحموعة وتحتوى عناصر تحمل أسماء مؤقتة كالتالى : أنون تريوم ، أنون كواديريوم، أنون بينتينيوم، أنون هيكسينيوم.

عناصر قابلة للتشغيل

الخصائص

This section outlines relevant physical and chemical properties of the other metals. For complete profiles, including history, production, specific uses, and biological roles and precautions, see the main article for each element. Abbreviations: MH—Moh's hardness; BCN—bulk coordination number.

المجموعة 12

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

الكادميوم is a soft, ductile metal (MH 2.0) that undergoes substantial deformation, under load, at room temperature. 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. The oxides of cadmium in its preferred oxidation state of +2, namely CdO and CdOH₂, are weakly amphoteric; it forms cadmates in strongly basic solutions. Cadmium forms Zintl phases such as LiCd, RbCd₁₃ and CsCd₁₃. 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), the cadmium vapour oxidizes, 'with a reddish-yellow flame, dispersing as an aerosol of potentially lethal CdO particles.' والكادميوم، عدا ذلك، مستقر في الهواء والماء، في الظروف العادية، محمياً بطبقة من أكسيد الكادميوم.

الزئبق 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. Solid mercury (MH 1.5) has a distorted crystalline structure, with mixed metallic-covalent bonding, and a BCN of 6. 'All of the [Group 12] metals, but especially mercury, tend to form covalent rather than ionic compounds.' The oxide of mercury in its preferred oxidation state (HgO; +2) is weakly amphoteric, as is the congener sulfide HgS. It forms anionic thiomercurates (such as Na₂HgS₂ and BaHgS₃) in strongly basic solutions. It forms or is a part of Zintl phases such as NaHg and K₈In₁₀Hg. Mercury is a relatively inert metal, showing little oxide formation at room temperature.

المجموعة 13

الألومنيوم in pure form is a soft metal (MH 3.0) with low mechanical strength. It has a close-packed structure (BCN 12) showing some evidence of partially directional bonding. It has a low melting point (just over half that of steel) and a high thermal conductivity. Its strength is halved at 200 °C, and for many of its alloys is minimal at 300 °C. The latter three properties of aluminium limit its use to situations where fire protection is not required, or necessitate the provision of increased fire protection. It bonds covalently in most of its compounds; has an amphoteric oxide; and can form anionic aluminates. Aluminium forms Zintl phases such as LiAl, Ca₃Al₂Sb₆, and SrAl₂. A thin protective layer of oxide confers a reasonable degree of corrosion resistance. It is susceptible to attack in low pH (<4) and high (> 8.5) pH conditions, a phenomenon that is generally more pronounced in the case of commercial purity aluminium and aluminium alloys. Given many of these properties and its proximity to the dividing line between metals and nonmetals, aluminium is occasionally classified as a metalloid. 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; and it has a high electrical conductivity. At lower temperatures, aluminium increases its deformation strength (as do most materials) whilst maintaining ductility (as do face-centred cubic metals generally). Chemically, bulk aluminium is a strongly electropositive metal, with a high negative electrode potential.

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

الإنديوم is a soft, highly ductile metal (MH 1.0) with a low tensile strength. It has a partially distorted crystalline structure (BCN 4+8) associated with incompletely ionised atoms. The tendency of indium '...to form covalent compounds is one of the more important properties influencing its electrochemical behavior'. 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. Indium forms Zintl phases such as LiIn, Na₂In and Rb₂In₃. Indium does not oxidize in air at ambient conditions.

الثاليوم is a soft, reactive metal (MH 1.0), so much so that it has no structural uses. 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. 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. It is the only one of the Group 13 elements to react with air at room temperature, slowly forming the amphoteric oxide Tl₂O₃. It forms anionic thallates such as Tl₃TlO₃, Na₃Tl(OH)₆, NaTlO₂, and KTlO₂, and is present as the Tl^– thallide anion in the compound CsTl. Thallium forms Zintl phases, such as Na₂Tl, Na₂K₂₁Tl₁₉, CsTl and Sr₅Tl₃H.

المجموعة 14

الصفيح is a soft, exceptionally weak metal (MH 1.5); a 1-cm thick rod will bend easily under mild finger pressure. It has an irregularly coordinated crystalline structure (BCN 4+2) associated with incompletely ionised atoms. All of the Group 14 elements form compounds in which they are in the +4, predominately covalent, oxidation state; even in the +2 oxidation state tin generally forms covalent bonds. The oxides of tin in its preferred oxidation state of +2, namely SnO and Sn(OH)₂, are amphoteric; it forms stannites in strongly basic solutions. 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. It has good corrosion resistance in air on account of forming a thin protective oxide layer. Pure tin has no structural uses. It is used in lead-free solders, and as a hardening agent in alloys of other metals, such as copper, lead, titanium and zinc.

الرصاص is a soft metal (MH 1.5) which, in many cases, is unable to support its own weight. 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. It forms a semi-covalent dioxide PbO₂; a covalently bonded sulfide PbS; covalently bonded halides; 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. The oxide of lead in its preferred oxidation state (PbO; +2) is amphoteric; it forms anionic plumbates in strongly basic solutions. Lead forms Zintl phases such as CsPb, Sr₃₁Pb₂₀, La₅Pb₃N and Yb₃Pb₂₀. 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.

المجموعة 15

البزموت is a slightly radioactive, soft metal (MH 2.5) that is too brittle for any structural use. It has an open-packed crystalline structure (BCN 3+3) with bonding that is intermediate between metallic and covalent. For a metal, it has exceptionally low electrical and thermal conductivity. Most of the ordinary compounds of bismuth are covalent in nature. The oxide, Bi₂O₃ is predominately basic but will act as a weak acid in warm, very concentrated KOH. It can also be fused with potassium hydroxide in air, resulting in a brown mass of potassium bismuthate. The solution chemistry of bismuth is characterised by the formation of oxyanions; it forns anionic bismuthates in strongly basic solutions. Bismuth forms Zintl phases such as NaBi, Rb₇In₄Bi₆ and Ba₁₁Cd₈Bi₁₄. Bailar et al. 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.'

المجموعة 16

الپولونيوم is radioactive, soft metal with a hardness similar to lead. It has a simple cublc crystalline structure characterised (as determined by electron density calculations) by partially directional bonding, and a BCN of 6. Such a structure ordinarily results in very low ductility and fracture resistance however polonium has been predicted to be a ductile metal. It forms a covalent hydride; its halides are covalent, volatile compounds, resembling those of tellurium. The oxide of polonium in its preferred oxidation state (PoO₂; +4) is predominately basic, but amphoteric if dissolved in concentrated aqueous alkali, or fused with potassium hydroxide in air. The yellow polonate(IV) ion PoO2−3 is known in aqueous solutions of low Cl^‒ concentration and high pH. Polonides such as Na₂Po, BePo, ZnPo, CdPo and HgPo feature Po^2– anions; except for HgPo these are some of the more stable of the polonium compounds.

تجميعات ذات صلة

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.

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

Borderline metals

Parish 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.

Chemically weak metals

Rayner-Canham and Overton 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 berylllium, aluminium, zinc, gallium, tin, lead, antimony, bismuth, and polonium.

الفلزات الثقيلة (بنقاط انصهار منخفضة)

Van Wert 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 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.

الفلزات الأقل نمطية

Habashi 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).

اللافلزات

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. Sometimes beryllium and gallium are included as metametals despite having low ductility.

Ordinary metals

Abrikosov 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. Gray identifies as ordinary metals: aluminium, gallium, indium, thallium, element 113, tin, lead, element 114, bismuth, element 115, and element 116. He adds that, 'in reality most of the metals that people think of as ordinary are in fact transition 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.

Peculiar metals

Slater 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 whereas the peculiar metals have structures involving directional bonding. More recently, Joshua observed that the peculiar metals have mixed metallic-covalent bonding.

الفلزات الفقيرة

Farrell and Van Sicien use the term poor metal, for simplicity, 'to denote one with a significant covalent, or directional character.' Hill and Holman 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. 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.'

فلزات ما بعد الانتنطقية

The term post-transition metal is generally used to describe the category of metallic elements in periods 4–6 of the periodic table, to the right of the transition elements. As this description excludes aluminium, a period ثلاثة metal, the post-transition elements thereby form a subset of the other metals. The post-transition metals generally show reduced electropositivity, anionic species formation and a capacity to combine with electropositive metals to give Zintl phases. Compounds of the group 12 metals (zinc, cadmium and mercury) are markedly non-ionic in character, both in structure and properties. Simple cationic chemistry in the group 14 metals, tin and lead, is the exception rather than the norm.

فلزات انتنطقية

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.' Cheronis, Parsons and Ronneberg 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.'

الهامش

Citations

شاهد أيضا

• الجدول الدوري .

المصادر

• ويكيبيديا الإنجليزية.

نطقب:Periodic table (32 columns, compact)