Cadmium (Cd)
Transition metal
Cadmium is a soft, bluish metal chemically similar to zinc but far more toxic. Once common in rechargeable NiCd batteries, pigments and platings, it is now heavily restricted, though it remains in solar panels and nuclear control rods.
Position on the periodic table
Atomic properties
| Atomic number | 48 |
|---|---|
| Atomic mass | 112.414 amu |
| Electron configuration | 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 |
| Noble gas shorthand | [Kr] 4d10 5s2 |
| Electrons per shell | 2, 8, 18, 18, 2 |
| Valence electrons (outer shell) | 2 |
| Common oxidation states | +2 |
| Electronegativity (Pauling) | 1.69 |
| Covalent radius (approx.) | 144 pm |
| First ionization energy | 867.8 kJ/mol |
| Electron affinity | -68 kJ/mol |
Physical properties
| State at 25 °C | Solid |
|---|---|
| Density | 8.65 g/cm³ |
| Melting point | 321.07 °C (594.22 K) |
| Boiling point | 766.85 °C (1040 K) |
| Appearance | silvery bluish-gray metallic |
| Radioactive | No |
| Origin | Occurs naturally |
Electron configuration of cadmium
Cadmium's ground-state electron configuration is 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10, usually shortened to [Kr] 4d10 5s2. Its electrons occupy 5 shells (2, 8, 18, 18, 2), placing it in period 5 of the d-block. Explore it interactively in the electron configuration calculator.
Uses of cadmium
- NiCd batteries (declining)
- CdTe thin-film solar panels
- Neutron-absorbing reactor control rods
- Artist pigments (restricted)
Biological role: None — toxic; it accumulates in kidneys over a lifetime.
Occurrence: Obtained almost entirely as a by-product of zinc refining.
Common compounds of cadmium
CdS
Cadmium sulfide
CdTe
Cadmium telluride
History and discovery
Discovered: 1817 — Karl Samuel Leberecht Hermann. Name origin: From Latin cadmia, the old name for zinc ore, in which it was found.
Friedrich Stromeyer discovered cadmium in 1817 as an impurity in zinc carbonate.
Safety notes
Cadmium is a cumulative toxin and carcinogen — a key reason for battery recycling programmes.
Educational context only — always follow your school's laboratory rules and never handle chemicals without proper supervision. See our disclaimer.
Practice questions
Quick practice: Cadmium
1. What is the chemical symbol of Cadmium?
2. What is the atomic number of Cadmium?
3. Which category does Cadmium belong to?
4. What is the state of Cadmium at room temperature?
5. Which period of the periodic table is Cadmium in?
Cadmium FAQs
What is the atomic number of cadmium?
Cadmium's atomic number is 48 — every cadmium atom has 48 protons in its nucleus.
What is the symbol for cadmium?
Cd. From Latin cadmia, the old name for zinc ore, in which it was found.
Is cadmium a metal, nonmetal, or metalloid?
Cadmium is classified as a transition metal.
What state is cadmium at room temperature?
At about 25 °C, cadmium is a solid. It melts at 321.07 °C.
What is cadmium used for?
Key uses include: nicd batteries (declining); cdte thin-film solar panels; neutron-absorbing reactor control rods.
Related elements
Keep working with this element
Spotted an error? Report a correction · Data sources