Cobalt

Atomic symbol: Co
Atomic number: 27
Atomic mass: 58.93

Appearance: Hard, blueish-gray solid at 25°C

Group: 9
Period: 4
Series: Transition metals
Block: d
Electron configuration: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁷ 4s²

Used in lithium-ion batteries and a common metal in high strength, wear-resistant alloys.

Also used for thousands of years to color glass, ceramics and jewelry dark blue.

Fun Fact! The isotope Cobalt-60 is used to create gamma rays which are used to treat cancer and to sterilize medical supplies.