Californium

Californium is atom number 98 — every Californium atom has exactly 98 protons in its center, and that number is what makes it Californium and nothing else. Its symbol is Cf. At room temperature it is a solid.

Californium is a radioactive metallic chemical element with symbol Cf and atomic number 98. The element was first made in 1950 at the University of California Radiation Laboratory in Berkeley, by bombarding curium with alpha particles (helium-4 ions). It is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium).

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

Californium sits in period 7, group 3 of the f-block. Its 98 electrons fill shells of 2, 8, 18, 32, 28, 8, 2 — written as [Rn] 5f10 7s2. Its electronegativity is 1.3 on the Pauling scale, and pulling the first electron off takes 608 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 4d10 5p6 6s2 4f14 5d10 6p6 7s2 5f10
Ionization energies (kJ/mol): 608
Electron affinity: -97.31 kJ/mol · Electronegativity (Pauling): 1.3
Density: 15.1 g/cm³ · melts 1173 K · boils 1743 K

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