Rhodium

Rhodium is atom number 45 — every Rhodium atom has exactly 45 protons in its center, and that number is what makes it Rhodium and nothing else. Its symbol is Rh. At room temperature it is a solid.

Rhodium is a chemical element with symbol Rh and atomic number 45. It is a rare, silvery-white, hard, and chemically inert transition metal. It is a member of the platinum group.

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

Rhodium sits in period 5, group 9 of the d-block. Its 45 electrons fill shells of 2, 8, 18, 16, 1 — written as [Kr] 4d8 5s1. Its electronegativity is 2.28 on the Pauling scale, and pulling the first electron off takes 719.7 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 4d8
Ionization energies (kJ/mol): 719.7, 1740, 2997
Electron affinity: 110.27 kJ/mol · Electronegativity (Pauling): 2.28
Density: 12.41 g/cm³ · melts 2237 K · boils 3968 K

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