27Co58.933
Transition Metald-block
Cobalt
Element 27 on the periodic table, symbol Co, group 9, period 4.
Cobalt is a chemical element with symbol Co and atomic number 27. Like nickel, cobalt in the Earth's crust is found only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.
Appearance: hard lustrous gray metal
Properties
- Atomic Number
- 27
- Atomic Mass
- 58.9332 u
- Group
- 9
- Period
- 4
- Block
- d-block
- Category
- Transition Metal
- State at 25 °C
- Solid
- Melting Point
- 1,768 K · 1,494.9 °C
- Boiling Point
- 3,200 K · 2,926.9 °C
- Density
- 8.9 g/cm³
- Atomic Radius
- 135 pm
- Electronegativity
- 1.88
- Oxidation States
- +2, +3
- Abundance in Crust
- 25 mg/kg
- Discovered
- 1735
- Discovered By
- Georg Brandt
Electron Configuration
[Ar] 3d7 4s2
1s2 2s2 2p6 3s2 3p6 4s2 3d7
Ionisation Energies (kJ/mol)
- 1. 760.4
- 2. 1,648
- 3. 3,232
- 4. 4,950
- 5. 7,670
- 6. 9,840
- 7. 12,440
- 8. 15,230
Elements near Cobalt
Elements in the same group share the number of outer electrons and behave in similar ways. Elements in the same period share a shell, so they change steadily from left to right.