WebElements Periodic Table of the Elements | Cadmium

Cadmium: the essentials

Cadmium is a soft, bluish-white metal and is easily cut with a knife. It is similar in many respects to zinc. Interestingly, aa characteristic cadmium "scream" is heard on bending a cadmium bar (such as that illustrated above). Cadmium and its compounds are highly toxic. Silver solder, which contains cadmium, should be handled with care.

Table: basic information about and classifications of cadmium.
Name: Cadmium Symbol: Cd Atomic number: 48 Atomic weight: 112.411 (8) [see note g] Standard state: solid at 298 K CAS Registry ID: 7440-43-9	Group in periodic table: 12 Group name: (none) Period in periodic table: 5 Block in periodic table: d-block Colour: silvery grey metallic Classification: Metallic

Cadmium: historical information

Cadmium was discovered by Friedrich Strohmeyer at 1817 in Germany. Origin of name: somewhat confusingly, from the Latin word "cadmia" meaning "calamine" (zinc carbonate, ZnCO₃) and from the Greek word "kadmeia" with the same meaning..

Cadmium was discovered by Friedrich Stromeyer in 1817 from an impurity in some samples pf zinc carbonate, ZnCO₃. He noted that these particular samples changed colour on heating, which pure zinc carbonate does not. He was persistent enough to follow this observation through and he eventually isolated some cadmium metal by roasting and reduction of the sulphide.

Cadmium: physical properties

Melting point: 594.22 [or 321.07 °C (609.93 °F)] K
Boiling point: 1040 [or 767 °C (1413 °F)] K
Density of solid: 8650 kg m^-3

Ground state electron configuration: [Kr].4d¹⁰.5s²
Shell structure: 2.8.18.18.2
Term symbol: ¹S₀
Pauling electronegativity: 1.69 (Pauling units)
First ionisation energy: 867.8 kJ mol^-1
Second ionisation energy: 1631.4 kJ mol^-1

Isolation

Isolation: it is rare that preparation of cadmium in the laboratory should be required bacause of environmental concerns about cadmium. The isolation of cadmium is associated with zinc recovery as cadmium is an impurity in zinc ores. Most zinc production is based upon sulphide ores. These are roasted in industrial plants to form zinc oxide, ZnO. This may be reduced with carbon to form zinc metal, but in practice ingenious technology is required to ensure that the resulting zinc does not contain oxide impurities.

ZnO + C → Zn + CO

ZnO + CO → Zn + CO₂

CO₂ + C → 2CO

After this process, zinc may be refined by distillation under vacuum and this process also allows the separation of any cadmium present in the crude zinc.

The other type of extraction of zinc is electrolytic. Dissolution of crude zinc oxide, ZnO, in sulphuric acid gives zinc sulphate, ZnSO₄ in solution. Before electrolysis to produce zinc, the cadmium impurity and is removed as a precipitate by the addition of zinc dust as cadmium sulphate.

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Cu	Zn	Ga
Ag	Cd	In
Au	Hg	Tl

Cadmium	Cadmium
Cadmium	Cadmium
Cadmio	Cadmio
Kadmium	Cádmio

Cadmium
- Essential data: names, symbol, atomic number, and atomic weight; block, period, and group in periodic table; description; standard state; registry number; and isolation
- History: meaning of name; discovery; and history of the element
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Cadmium around us
- Geology: Abundance of elements in the universe; the sun; meteorites; Earth's crust; oceans; and streams
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Chemistry and compounds
- Compounds: halides, oxides, sulfides, hydrides, and complexes; lattice energies; and reduction potentials
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Element properties
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1	2															3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18

1 H																															2 He
3 Li	4 Be																									5 B	6 C	7 N	8 O	9 F	10 Ne
11 Na	12 Mg																									13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
19 K	20 Ca															21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
37 Rb	38 Sr															39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
55 Cs	56 Ba	57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
87 Fr	88 Ra	89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Uut	114 Fl	115 Uup	116 Lv	117 Uus	118 Uuo

Cadmium

Cadmium: the essentials

Cadmium: historical information

Cadmium: physical properties

Cadmium: orbital properties

Isolation

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