Strontium

Strontium is atom number 38 — every Strontium atom has exactly 38 protons in its center, and that number is what makes it Strontium and nothing else. Its symbol is Sr. At room temperature it is a solid.

Strontium is a chemical element with symbol Sr and atomic number 38. An alkaline earth metal, strontium is a soft silver-white or yellowish metallic element that is highly reactive chemically. The metal turns yellow when it is exposed to air.

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

Strontium sits in period 5, group 2 of the s-block. Its 38 electrons fill shells of 2, 8, 18, 8, 2 — written as [Kr] 5s2. Its electronegativity is 0.95 on the Pauling scale, and pulling the first electron off takes 549.5 kJ/mol. The outermost shell holds 2 electrons — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2
Ionization energies (kJ/mol): 549.5, 1064.2, 4138, 5500, 6910, 8760, 10230, 11800 … (11 published)
Electron affinity: 5.023 kJ/mol · Electronegativity (Pauling): 0.95
Density: 2.64 g/cm³ · melts 1050 K · boils 1650 K

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