General properties
Name, symbolindium, In
Appearancesilvery lustrous gray
Indium in the periodic table
Hydrogen (diatomic nonmetal)

Helium (noble gas)
Lithium (alkali metal)
Beryllium (alkaline earth metal)

Boron (metalloid)
Carbon (polyatomic nonmetal)
Nitrogen (diatomic nonmetal)
Oxygen (diatomic nonmetal)
Fluorine (diatomic nonmetal)
Neon (noble gas)
Sodium (alkali metal)
Magnesium (alkaline earth metal)

Aluminium (post-transition metal)
Silicon (metalloid)
Phosphorus (polyatomic nonmetal)
Sulfur (polyatomic nonmetal)
Chlorine (diatomic nonmetal)
Argon (noble gas)
Potassium (alkali metal)
Calcium (alkaline earth metal)

Scandium (transition metal)
Titanium (transition metal)
Vanadium (transition metal)
Chromium (transition metal)
Manganese (transition metal)
Iron (transition metal)
Cobalt (transition metal)
Nickel (transition metal)
Copper (transition metal)
Zinc (transition metal)
Gallium (post-transition metal)
Germanium (metalloid)
Arsenic (metalloid)
Selenium (polyatomic nonmetal)
Bromine (diatomic nonmetal)
Krypton (noble gas)
Rubidium (alkali metal)
Strontium (alkaline earth metal)

Yttrium (transition metal)
Zirconium (transition metal)
Niobium (transition metal)
Molybdenum (transition metal)
Technetium (transition metal)
Ruthenium (transition metal)
Rhodium (transition metal)
Palladium (transition metal)
Silver (transition metal)
Cadmium (transition metal)
Indium (post-transition metal)
Tin (post-transition metal)
Antimony (metalloid)
Tellurium (metalloid)
Iodine (diatomic nonmetal)
Xenon (noble gas)
Caesium (alkali metal)
Barium (alkaline earth metal)
Lanthanum (lanthanide)
Cerium (lanthanide)
Praseodymium (lanthanide)
Neodymium (lanthanide)
Promethium (lanthanide)
Samarium (lanthanide)
Europium (lanthanide)
Gadolinium (lanthanide)
Terbium (lanthanide)
Dysprosium (lanthanide)
Holmium (lanthanide)
Erbium (lanthanide)
Thulium (lanthanide)
Ytterbium (lanthanide)
Lutetium (lanthanide)
Hafnium (transition metal)
Tantalum (transition metal)
Tungsten (transition metal)
Rhenium (transition metal)
Osmium (transition metal)
Iridium (transition metal)
Platinum (transition metal)
Gold (transition metal)
Mercury (transition metal)
Thallium (post-transition metal)
Lead (post-transition metal)
Bismuth (post-transition metal)
Polonium (post-transition metal)
Astatine (metalloid)
Radon (noble gas)
Francium (alkali metal)
Radium (alkaline earth metal)
Actinium (actinide)
Thorium (actinide)
Protactinium (actinide)
Uranium (actinide)
Neptunium (actinide)
Plutonium (actinide)
Americium (actinide)
Curium (actinide)
Berkelium (actinide)
Californium (actinide)
Einsteinium (actinide)
Fermium (actinide)
Mendelevium (actinide)
Nobelium (actinide)
Lawrencium (actinide)
Rutherfordium (transition metal)
Dubnium (transition metal)
Seaborgium (transition metal)
Bohrium (transition metal)
Hassium (transition metal)
Meitnerium (unknown chemical properties)
Darmstadtium (unknown chemical properties)
Roentgenium (unknown chemical properties)
Copernicium (transition metal)
Ununtrium (unknown chemical properties)
Flerovium (post-transition metal)
Ununpentium (unknown chemical properties)
Livermorium (unknown chemical properties)
Ununseptium (unknown chemical properties)
Ununoctium (unknown chemical properties)


Atomic number (Z)49
Group, blockgroup 13, p-block
Periodperiod 5
Element category post-transition metal
Standard atomic weight (±) (Ar)114.818(1)[1]
Electron configuration[Kr] 4d10 5s2 5p1
per shell
2, 8, 18, 18, 3
Physical properties
Melting point429.7485 K (156.5985 °C, 313.8773 °F)
Boiling point2345 K (2072 °C, 3762 °F)
Densitynear r.t.7.31 g/cm3
when liquid, at m.p.7.02 g/cm3
Triple point429.7445 K, ~1 kPa[2]
Heat of fusion3.281 kJ/mol
Heat of vaporization231.8 kJ/mol
Molar heat capacity26.74 J/(mol·K)
vapor pressure
P (Pa)1101001 k10 k100 k
at T (K)119613251485169019622340
Atomic properties
Oxidation states3, 2, 1, −1, −2, −5[3] (anamphoteric oxide)
ElectronegativityPauling scale: 1.78
Ionization energies1st: 558.3 kJ/mol
2nd: 1820.7 kJ/mol
3rd: 2704 kJ/mol
Atomic radiusempirical: 167 pm
Covalent radius142±5 pm
Van der Waals radius193 pm
Crystal structuretetragonal
Tetragonal crystal structure for indium
Speed of soundthin rod1215 m/s (at 20 °C)
Thermal expansion32.1 µm/(m·K) (at 25 °C)
Thermal conductivity81.8 W/(m·K)
Electrical resistivity83.7 nΩ·m (at 20 °C)
Magnetic orderingdiamagnetic[4]
Young's modulus11 GPa
Mohs hardness1.2
Brinell hardness8.8–10.0 MPa
CAS Number7440-74-6
DiscoveryFerdinand Reich andHieronymous Theodor Richter(1863)
First isolationHieronymous Theodor Richter(1867)
Most stable isotopes of indium
115In95.71%4.41×1014 yβ0.495115Sn
Decay modes in parentheses are predicted, but have not yet been observed