Transition metalElement 48 · d-block

Cadmium (Cd)

Cadmium (Cd) is a transition metal with atomic number 48 and a standard atomic weight of 112.41. At room temperature it is a solid that melts at 321 °C and boils at 767 °C.

48CdCadmium112.41

Atomic number

protons

Atomic weight

112.41

CIAAW 2024

Melting point

321 °C

594.22 K

Boiling point

767 °C

1,040.15 K

Density

8.69 g/cm³

near room temperature

Electronegativity

1.69

Pauling scale

State at 25 °C

Solid

Discovered

1817

Germany

Cadmium at a glance

Identity

Symbol	Cd
Atomic number (Z)	48
Atomic weight	112.41 ± 0.01 (CIAAW 2024)
Category	Transition metal
Group	12
Period	5
Block	d-block
CAS number	7440-43-9

Atomic properties

Electron configuration	[Kr] 4d¹⁰ 5s² Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s²
Electrons per shell	2, 8, 18, 18, 2
Oxidation states	+2 Less common: -2, +1
Electronegativity (Pauling)	1.69
First ionisation energy	8.994 eV (867.8 kJ/mol) 2nd: 16.908 eV · 3rd: 37.468 eV
Atomic radius (empirical)	155 pm
Covalent radius	136 pm
Van der Waals radius	218 pm

Physical properties

State at 25 °C	Solid
Melting point	321.1 °C · 609.9 °F · 594.22 K
Boiling point	767 °C · 1,412.6 °F · 1,040.15 K
Density	8.69 g/cm³
Specific heat capacity	0.232 J/(g·K)
Thermal conductivity	96.9 W/(m·K)
Crystal structure	Hexagonal

Isotopes & abundance

Natural occurrence	Primordial
Radioactive	No
Natural isotopes (abundance)	¹¹⁴Cd 28.754%, ¹¹²Cd 24.109%, ¹¹¹Cd 12.795%, ¹¹⁰Cd 12.47%, ¹¹³Cd 12.227% (radioactive), ¹¹⁶Cd 7.512% (radioactive)
Stable isotopes	7
Known isotopes	42
Abundance in Earth's crust	0.15 mg/kg
Abundance in seawater	0.00011 mg/L

Atomic weights: CIAAW Abridged Standard Atomic Weights 2024. Other properties: standard reference compilations, checked October 2026; predicted values are marked.

Cadmium electron configuration

Cadmium has 48 electrons. Written in short form, its ground-state configuration is [Kr] 4d¹⁰ 5s² — the electrons of the noble gas krypton, plus 4d¹⁰ 5s².Written out in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s².

4d↑↓↑↓↑↓↑↓↑↓

5s↑↓

Discovery and name

Discovered

1817 — Friedrich Stromeyer; also Karl Hermann and others · Germany.

Name

Latin cadmia (calamine, zinc ore).

Known for

Toxic; used in nickel–cadmium batteries, cadmium telluride solar cells and pigments. Its use is restricted in many products.

Isotopes of cadmium

Naturally occurring cadmium is a mix of 8 isotopes. Each has 48 protons; they differ in the number of neutrons:

Isotope	Protons	Neutrons	Natural abundance	Stability
¹¹⁴Cd	48	66	28.754%	stable
¹¹²Cd	48	64	24.109%	stable
¹¹¹Cd	48	63	12.795%	stable
¹¹⁰Cd	48	62	12.47%	stable
¹¹³Cd	48	65	12.227%	radioactive · half-life 8.04 × 10¹⁵ years
¹¹⁶Cd	48	68	7.512%	radioactive · half-life 26.9 × 10¹⁸ years
¹⁰⁶Cd	48	58	1.245%	stable
¹⁰⁸Cd	48	60	0.888%	stable

42 isotopes of cadmium are known in our data set (half-lives as published in nuclear data tables).

Cadmium compared with group 12

The other elements in group 12, from top to bottom of the table:

Element	Z	Atomic weight	Melting point	Boiling point	Density	Electronegativity
Zinc	30	65.38	420 °C	907 °C	7.134 g/cm³	1.65
Cadmium	48	112.41	321 °C	767 °C	8.69 g/cm³	1.69
Mercury	80	200.59	-39 °C	357 °C	13.534 g/cm³	2
Copernicium	112	[285]	—	—	14 g/cm³ (pred.)	—

Frequently asked questions

6 answers

What is the atomic mass of cadmium?

The standard atomic weight of cadmium is 112.41 ± 0.01 (CIAAW 2024), so one mole weighs about 112.41 grams.

How many protons, neutrons and electrons does cadmium have?

A neutral cadmium atom has 48 protons and 48 electrons. Its most common isotope, cadmium-114, has 66 neutrons.

What is the electron configuration of cadmium?

[Kr] 4d¹⁰ 5s² (in full: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s²).

What are the melting and boiling points of cadmium?

Cadmium melts at 321.07 °C (609.9 °F) and boils at 767 °C (1,412.6 °F).

Is cadmium a metal?

Cadmium is a metal. It is in group 12, period 5, and is a solid at room temperature.

Who discovered cadmium?

1817 — Friedrich Stromeyer; also Karl Hermann and others (Germany).