Cobalt (symbol Co, atomic number 27) is a magnetic metal used in jet-engine superalloys and lithium-ion battery cathodes. It is classified as a transition metal and sits in group 9, period 4 of the periodic table.
Overview
Cobalt is the chemical element with atomic number 27 and the symbol Co. With a standard atomic weight of 58.933, it is a transition metal. In the periodic table it occupies group 9 and period 4, and under standard conditions it is normally a solid. Cobalt is a magnetic metal used in jet-engine superalloys and lithium-ion battery cathodes.
Atomic structure
An atom of Cobalt has 27 protons in its nucleus and, when neutral, 27 electrons arranged in the configuration [Ar] 3d7 4s2. Its standard atomic weight of 58.933 reflects the natural mix of its stable isotopes.
Discovery and place in the table
Cobalt was discovered in 1735 by Georg Brandt. It follows Iron (Fe) and precedes Nickel (Ni) in order of atomic number.
| Atomic number | 27 |
|---|---|
| Symbol | Co |
| Atomic mass | 58.933 |
| Category | Transition metal |
| Group | 9 |
| Period | 4 |
| Electron configuration | [Ar] 3d7 4s2 |
| Phase at STP | Solid |
| Discovered | 1735 (Georg Brandt) |