Nickel

Nickel is atom number 28 — every Nickel atom has exactly 28 protons in its center, and that number is what makes it Nickel and nothing else. Its symbol is Ni. At room temperature it is a solid.

Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile.

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

Nickel sits in period 4, group 10 of the d-block. Its 28 electrons fill shells of 2, 8, 16, 2 — written as [Ar] 3d8 4s2. Its electronegativity is 1.91 on the Pauling scale, and pulling the first electron off takes 737.1 kJ/mol. The outermost shell holds 2 electrons — the ones that do all the chemistry.

Full configuration: 1s2 2s2 2p6 3s2 3p6 4s2 3d8
Ionization energies (kJ/mol): 737.1, 1753, 3395, 5300, 7339, 10400, 12800, 15600 … (28 published)
Electron affinity: 111.65 kJ/mol · Electronegativity (Pauling): 1.91
Density: 8.908 g/cm³ · melts 1728 K · boils 3003 K

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