Aluminium

Aluminium is atom number 13 — every Aluminium atom has exactly 13 protons in its center, and that number is what makes it Aluminium and nothing else. Its symbol is Al. At room temperature it is a solid.

Aluminium (or aluminum; see different endings) is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal. Aluminium is the third most abundant element (after oxygen and silicon), and the most abundant metal, in the Earth's crust.

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

Aluminium sits in period 3, group 13 of the p-block. Its 13 electrons fill shells of 2, 8, 3 — written as [Ne] 3s2 3p1. Its electronegativity is 1.61 on the Pauling scale, and pulling the first electron off takes 577.5 kJ/mol. The outermost shell holds 3 electrons — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p1
Ionization energies (kJ/mol): 577.5, 1816.7, 2744.8, 11577, 14842, 18379, 23326, 27465 … (13 published)
Electron affinity: 41.762 kJ/mol · Electronegativity (Pauling): 1.61
Density: 2.7 g/cm³ · melts 933.47 K · boils 2743 K

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