Co
Cobalt
Cobalt is a chemical element with the symbol Co and atomic number 27. It has a standard atomic weight of 58.933, sits in period 4 and group 9, and is classified as a transition metal.
Properties
| Symbol | Co |
|---|---|
| Atomic number | 27 |
| Standard atomic weight | 58.933 |
| Category | Transition metal |
| Group | 9 |
| Period | 4 |
| Electron configuration | [Ar] 3d7 4s2 |
| Outer-shell electrons | 2 |
The figure of 58.933 is a standard atomic weight.
Compounds containing cobalt
2 of the compounds in this reference contain Co, listed by the fraction of their mass it makes up.
| Compound | Formula | Atoms | % by mass |
|---|---|---|---|
| cobalt chloride | Cl2Co | 1 | 45.4% |
| cyanocobalamin | C63H88CoN14O14P | 1 | 4.3% |
Calculate with cobalt
- Molar mass of any formula containing it
- Electron configuration, including ions
- Effective nuclear charge by Slater's rules
- Average atomic mass from isotope abundances
Group 9
Atomic weights are the IUPAC 2021 standard values, abridged to the conventional five significant figures. Group, period, category and electron configuration are derived from the atomic number rather than stored, so they cannot drift out of step with it.