Radon

Radon is atom number 86 — every Radon atom has exactly 86 protons in its center, and that number is what makes it Radon and nothing else. Its symbol is Rn. At room temperature it is a gas.

Radon is a chemical element with symbol Rn and atomic number 86. It is a radioactive, colorless, odorless, tasteless noble gas, occurring naturally as a decay product of radium. Its most stable isotope, 222Rn, has a half-life of 3.8 days.

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

Radon sits in period 6, group 18 of the p-block. Its 86 electrons fill shells of 2, 8, 18, 32, 18, 8 — written as [Xe] 4f14 5d10 6s2 6p6. Its electronegativity is 2.2 on the Pauling scale, and pulling the first electron off takes 1037 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 5s2 4d10 5p6 6s2 4f14 5d10 6p6
Ionization energies (kJ/mol): 1037
Electron affinity: -68 kJ/mol · Electronegativity (Pauling): 2.2
Density: 9.73 g/L · melts 202 K · boils 211.5 K

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