- 🇬🇧 Cadmium
- 🇺🇦 Кадмій
- 🇨🇳 鎘
- 🇳🇱 Cadmium
- 🇫🇷 Cadmium
- 🇩🇪 Cadmium
- 🇮🇱 קדמיום
- 🇮🇹 Cadmio
- 🇯🇵 カドミウム
- 🇵🇹 Cádmio
- 🇪🇸 Cadmio
- 🇸🇪 Kadmium
- 🇷🇺 Кадмий
- Name: cadmium
- Symbol: Cd
- Atomic number: 48
- Relative atomic mass (Ar): 112.414 (4) g [see note g]
- Standard state: solid at 298 K
- Appearance: silvery grey metallic
- Classification: Metallic
- Group in periodic table: 12
- Group name: (none)
- Period in periodic table: 5
- Block in periodic table: d
- Shell structure: 2.8.18.18.2
- CAS Registry: 7440-43-9
Cadmium atoms have 48 electrons and the shell structure is 2.8.18.18.2. The ground state electronic configuration of neutral cadmium is [Kr].4d10.5s2 and the term symbol of cadmium is 1S0.
Cadmium: description
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.
cadmium balls
Science and Ink cartoon for cadmium
Cartoon by Nick D Kim ([Science and Ink], used by permission).
Cadmium: physical properties
- Density of the chemical elements on a miniature periodic table spark table Density of solid: 8650 kg m-3
- Molar volume of the chemical elements on a miniature periodic table spark table Molar volume: 13.00 cm3
- Thermal conductivity of the chemical elements on a miniature periodic table spark table Thermal conductivity: 97 W m‑1 K‑1
Cadmium: heat properties
- Melting point on a miniature periodic table spark table Melting point: 594.22 [321.07 °C (609.93 °F)] K
- Boiling point on a miniature periodic table spark table Boiling point: 1040 [767 °C (1413 °F)] K
- Enthalpy of fusion on a miniature periodic table spark table Enthalpy of fusion: 20.5 kJ mol-1
Cadmium: atom sizes
- Atomic radius (empirical) of the chemical elements on a miniature periodic table spark table Atomic radius (empirical): 155 pm
- Covalent (single bond) radius on a periodic table spark table Molecular single bond covalent radius: 136 (coordination number 1) ppm
- van der Waals radius on a periodic table spark table van der Waals radius: 249 ppm
Cadmium: electronegativities
- Pauling electronegativity of the chemical elements on a miniature periodic table spark table Pauling electronegativity: 1.69 (Pauling units)
- Allred-Rochow electronegativity of the chemical elements on a miniature periodic table spark tableAllred Rochow electronegativity: 1.46 (Pauling units)
- Mulliken-Jaffe electronegativity of the chemical elements on a miniature periodic table spark tableMulliken-Jaffe electronegativity: 1.53 (sp orbital)
Cadmium: orbital properties
- First ionization energy the chemical elements on a miniature periodic table spark table First ionisation energy: 867.77 kJ mol‑1
- Second ionization energy the chemical elements on a miniature periodic table spark table Second ionisation energy: 1631.40 kJ mol‑1
- Third ionization energy the chemical elements on a miniature periodic table spark table Third ionisation energy: 3615.1 kJ mol‑1
Cadmium: abundances
- Chemical elements abundance by weight in the universe on a miniature periodic table spark tableUniverse: 2 ppb by weight
- Chemical elements abundance by weight in the earth's crust on a miniature periodic table spark tableCrustal rocks: 150 ppb by weight
- Chemical elements abundance by weight in humans on a miniature periodic table spark tableHuman: 700 ppb by weight
Cadmium: crystal structure
Cadmium: biological data
- Human abundance by weight of the chemical elements on a miniature periodic table spark table Human abundance by weight: 700 ppb by weight
Cadmium might be a necessary element in very, very, small quantities in rats.
Inhalation of cadmium dust causes problems for the respiratory tract and for the kidneys. Death may follow. Ingestion of any significant amount of cadmium causes immediate poisoning and damage to the liver and the kidneys.
Cadmium: uses
Cadmium: reactions
Reactions of cadmium as the element with air, water, halogens, acids, and bases where known.
Cadmium: binary compounds
Binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and other compounds of cadmium where known.
Cadmium: compound properties
Bond strengths; lattice energies of cadmium halides, hydrides, oxides (where known); and reduction potentials where known.
Cadmium: history
Cadmium was discovered by Friedrich Strohmeyer in 1817 at 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: isotopes
The nine stable Cadmium isotopes are used for many different purposes. Cd-110 is used for the production of the radioisotope In-110, while Cd-112 is used in the production of the widely used diagnostic radioisotope In-111. Cd-108 is used in the production of Cd-109 which is a calibration source for 88 keV gamma radiation. The even numbered Cd isotopes (mainly Cd-110, Cd-112, Cd-114 and Cd-116) are used to improve the power output and coherence length of HeCd lasers.
Cadmium: 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.