Indium

Indium is atom number 49 — every Indium atom has exactly 49 protons in its center, and that number is what makes it Indium and nothing else. Its symbol is In. At room temperature it is a solid.

Indium 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.

Summary from the source dataset, derived from Wikipedia (CC BY-SA 3.0) · original article

Indium sits in period 5, group 13 of the p-block. Its 49 electrons fill shells of 2, 8, 18, 18, 3 — written as [Kr] 4d10 5s2 5p1. Its electronegativity is 1.78 on the Pauling scale, and pulling the first electron off takes 558.3 kJ/mol. The outermost shell holds 3 electrons — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p1
Ionization energies (kJ/mol): 558.3, 1820.7, 2704, 5210
Electron affinity: 37.043 kJ/mol · Electronegativity (Pauling): 1.78
Density: 7.31 g/cm³ · melts 429.7485 K · boils 2345 K

Values exactly as published — see where the data comes from.