Roentgenium

Roentgenium is atom number 111 — every Roentgenium atom has exactly 111 protons in its center, and that number is what makes it Roentgenium and nothing else. Its symbol is Rg. At room temperature it is a solid.

Roentgenium is a chemical element with symbol Rg and atomic number 111. It is an extremely radioactive synthetic element (an element that can be created in a laboratory but is not found in nature); the most stable known isotope, roentgenium-282, has a half-life of 2.1 minutes. Roentgenium was first created in 1994 by the GSI Helmholtz Centre for Heavy Ion Research near Darmstadt, Germany.

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

Roentgenium sits in period 7, group 11 of the d-block. Its 111 electrons fill shells of 2, 8, 18, 32, 32, 17, 2 — written as *[Rn] 5f14 6d10 7s1. Its electronegativity is — on the Pauling scale. 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 5d10 6p6 7s2 5f14 6d9
Electron affinity: 151 kJ/mol · Electronegativity (Pauling): —
Density: 28.7 g/cm³ · melts — · boils —

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