Ruthenium

Ruthenium is atom number 44 — every Ruthenium atom has exactly 44 protons in its center, and that number is what makes it Ruthenium and nothing else. Its symbol is Ru. At room temperature it is a solid.

Ruthenium is a chemical element with symbol Ru and atomic number 44. It is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals.

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

Ruthenium sits in period 5, group 8 of the d-block. Its 44 electrons fill shells of 2, 8, 18, 15, 1 — written as [Kr] 4d7 5s1. Its electronegativity is 2.2 on the Pauling scale, and pulling the first electron off takes 710.2 kJ/mol. The outermost shell holds 1 electron — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d7
Ionization energies (kJ/mol): 710.2, 1620, 2747
Electron affinity: 100.96 kJ/mol · Electronegativity (Pauling): 2.2
Density: 12.45 g/cm³ · melts 2607 K · boils 4423 K

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