Atomic number 29
Copper
Transition metal
Quick facts
- Atomic mass
- 63.546
- Group
- 11
- Period
- 4
- State (STP)
- solid
- Electronegativity
- 1.90
- Common ox. states
- +1, +2
Properties
Electron configuration
[Ar] 3d¹⁰ 4s¹
- Ionization energy
- 745.5 kJ/mol
- Electron affinity
- 119.2 kJ/mol
- Melting point
- 1357.77 K (1084.6 °C)
- Boiling point
- 2835.00 K (2561.8 °C)
How it bonds
Copper is one of the textbook electron-config exceptions: 3d¹⁰ 4s¹ (filled d shell) is more stable than the expected 3d⁹ 4s². Forms +1 (Cu₂O, red) and +2 (CuSO₄·5H₂O, the famous blue copper sulfate). Copper's high electronegativity and noble character make it useful for wiring and plumbing — it doesn't corrode easily in air.