Osmium

Osmium is atom number 76 — every Osmium atom has exactly 76 protons in its center, and that number is what makes it Osmium and nothing else. Its symbol is Os. At room temperature it is a solid.

Osmium (from Greek osme (ὀσμή) meaning "smell") is a chemical element with symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3.

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

Osmium sits in period 6, group 8 of the d-block. Its 76 electrons fill shells of 2, 8, 18, 32, 14, 2 — written as [Xe] 4f14 5d6 6s2. Its electronegativity is 2.2 on the Pauling scale, and pulling the first electron off takes 840 kJ/mol. The outermost shell holds 2 electrons — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d6
Ionization energies (kJ/mol): 840, 1600
Electron affinity: 103.99 kJ/mol · Electronegativity (Pauling): 2.2
Density: 22.59 g/cm³ · melts 3306 K · boils 5285 K

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