Krypton

Krypton is atom number 36 — every Krypton atom has exactly 36 protons in its center, and that number is what makes it Krypton and nothing else. Its symbol is Kr. At room temperature it is a gas.

Krypton (from Greek:κρυπτός kryptos "the hidden one") is a chemical element with symbol Kr and atomic number 36. It is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere, is isolated by fractionally distilling liquefied air, and is often used with other rare gases in fluorescent lamps.

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

Krypton sits in period 4, group 18 of the p-block. Its 36 electrons fill shells of 2, 8, 18, 8 — written as [Ar] 3d10 4s2 4p6. Its electronegativity is 3 on the Pauling scale, and pulling the first electron off takes 1350.8 kJ/mol. The outermost shell holds 8 electrons — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
Ionization energies (kJ/mol): 1350.8, 2350.4, 3565, 5070, 6240, 7570, 10710, 12138 … (30 published)
Electron affinity: -96 kJ/mol · Electronegativity (Pauling): 3
Density: 3.749 g/L · melts 115.78 K · boils 119.93 K

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