About

Indium is a very soft, silvery-white post-transition metal that is ductile and malleable. Its most important compound is indium tin oxide (ITO), which possesses the rare combination of being both transparent and electrically conductive. This unique property makes it essential for manufacturing transparent electrodes for touchscreens, LCDs, OLED displays, and thin-film solar panels.

Atomic Properties

Atomic Number49

Atomic Weight114.818 u

Neutrons (common)66

Electron Configuration[Kr] 4d¹⁰ 5s² 5p¹

Full Configuration1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p¹

Electrons per Shell2, 8, 18, 18, 3

Electronegativity1.78

Electron Affinity28.9 kJ/mol

Oxidation States+3, +1

Covalent Radius156 pm

Van der Waals Radius193 pm

Ionic Radius80 pm

Periodic Table Position

Group13

Period5

BlockP

Chemical SeriesPost-transition metals

Physical Properties

State at STPsolid

AppearanceSilvery lustrous gray metal, very soft and malleable

Crystal Structuretetragonal

Magnetic Orderingdiamagnetic

Speed of Sound1,215 m/s

Poisson Ratio0.33

Thermal Properties

Melting Point429.75 K

Boiling Point2,345 K

Triple Point429.75 K

Thermal Expansion0 1/K

Thermal Conductivity81.8 W/(m·K)

Specific Heat0.233 J/(g·K)

Molar Heat26.74 J/(mol·K)

Heat of Fusion3.281 kJ/mol

Heat of Vaporization231.8 kJ/mol

Abundance

In Earth's Crust0.25 ppm

In Ocean0 ppm

In Solar System0.001 ppm

In Universe0 ppm

Discovery

Discovered byFerdinand Reich, Hieronymous Theodor Richter

Discovery Year1,863

Occurrenceprimordial

CAS Number7440-74-6

Electron Configuration

Energy

↿⇂

↿

Isotopes of Indium

Symbol ▲	Mass (u) ▲	Abundance ▲	Half-life ▲	Decay Mode ▲
¹¹³In	112.904060	4.29%	Stable	Stable
¹¹⁵In	114.903880	95.71%	441 Ty	Beta Minus Decay

Interactive Visualization

Explore the 3D Bohr model of Indium in our interactive viewer.

View 3D Model of Indium