048Transition metal · Group 12 · Period 5

Cadmium

Cadmium (Cd) is element 48, a transition metal in the d-block — group 12, period 5. It is a solid at room temperature with 5 electron shells (2, 8, 18, 18, 2) and an atomic mass of 112.4144 u.

Atomic mass: 112.4 u
Phase · STP: solid
Melting: 594 K · 321 °C
Boiling: 1040 K · 767 °C
Electronegativity: 1.69
Density: 8.65 g/cm³

Photograph — Chemical Elements A Virtual Museum under a Creative Commons Attribution 3.0 Unported License, source: https://images-of-elements.com/cadmium.php

Identity

Atomic number: 48
Standard atomic weight: 112.4 u
Category: Transition metal
Group: 12
Period: 5
Block: d-block
Oxidation states: +2

Physical properties

Melting point: 594 K · 321 °C
Boiling point: 1040 K · 767 °C
Density: 8.65 g/cm³
Molar heat capacity: 26.02 J/(mol·K)
Atomic radius: 158 pm
Electron affinity: -68 kJ/mol

Atomic structure

48protons

64neutrons

48electrons

2valence e⁻

Noble-gas notation: [Kr] 4d10 5s2
Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10
Electrons per shell: 2, 8, 18, 18, 2

Periodic trends

Where Cadmium ranks across all 118 elements.

Electronegativity1.69

Ionization energy867.8 kJ/mol

Electron affinity-68 kJ/mol

Density8.65 g/cm³

Atomic radius158 pm

Ionization energies

Energy to remove each successive electron (kJ/mol).

867.8

1.6k

3.6k

Successive ionization energies (kJ/mol, log scale).

Discovery

Discovered: 1817
Discovered by: Karl Samuel Leberecht Hermann
Named by: Isotopes of cadmium
Appearance: silvery bluish-gray metallic