Symbol	In
Atomic number	49
Group	13 (Boron group)
Period	5
Block	p
Classification	Post-Transition Metal

Appearance	Silvery lustrous gray
Color	Silver

Number of protons	49 p+
Number of neutrons	66 n0
Number of electrons	49 e-

From Wikipedia, the free encyclopediaIndium is a chemical element with symbol In and atomic number 49. It is a post-transition metallic element that is rare in Earth's crust. The metal is very soft, malleable and easily fusible, with a melting point higher than sodium, but lower than lithium or tin.

Phase at STP	Solid
Density	7.31 g/cm3
Atomic weight	114.818 u

Melting point	429.749 K 156.599 °C 313.8782 °F
Boiling point	2345 K 2071.85 °C 3761.33 °F
Heat of vaporization	226.35 kJ/mol

Electronegativity (Pauling Scale)	1.78
Electron affinity	37.043 kJ/mol
Oxidation states	−5, −2, −1, +1, +2, +3 (an amphoteric oxide)
Ionization energies	558.3 kJ/mol 1820.7 kJ/mol 2704 kJ/mol 5210 kJ/mol

Electron configuration Shorthand configuration	[Kr] 4d10 5s2 5p1
Electron configuration Full configuration	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p1
Electron configuration chart	1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p1
Electrons per shell	2, 8, 18, 18, 3
Valence electrons	3
Valency electrons	3
Bohr model	Figure: Shell diagram of Indium (In) atom.
Orbital Diagram	1s 2s 2p 3s 3p 3d 4s 4p 4d 5s 5p

Discovery	Ferdinand Reich, Hieronymous Theodor Richter (1863)
First isolation	Hieronymous Theodor Richter (1864)
Discovery of indium In 1863, the German chemists Ferdinand Reich and Hieronymous Theodor Richter were testing ores from the mines around Freiberg, Saxony. They dissolved the minerals pyrite, arsenopyrite, galena and sphalerite in hydrochloric acid and distilled raw zinc chloride. Reich, who was color-blind, employed Richter as an assistant for detecting the colored spectral lines. Knowing that ores from that region sometimes contain thallium, they searched for the green thallium emission spectrum lines. Instead, they found a bright blue line. Because that blue line did not match any known element, they hypothesized a new element was present in the minerals. They named the element indium, from the indigo color seen in its spectrum, after the Latin indicum, meaning 'of India'. Richter went on to isolate the metal in 1864. An ingot of 0.5 kg (1.1 lb) was presented at the World Fair 1867. Reich and Richter later fell out when the latter claimed to be the sole discoverer.

CAS Number	7440-74-6
ChemSpider ID	4514408
EC number	231-180-0
PubChem CID Number	5359967