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Copper (Cu), element 29
Copper (Cu) is the chemical element with atomic number 29: a transition metal in group 11, period 4. At 25 °C it is a solid, with an atomic mass of 63.55 u.
Physical and chemical data
| Atomic number | 29 |
|---|---|
| Symbol | Cu |
| Atomic mass | 63.55 u |
| Density | 8.933 g/cm³ |
| Melting point | 1,084.62 °C (1,357.77 K) |
| Boiling point | 2,561.85 °C (2,835 K) |
| Electronegativity (Pauling) | 1.9 |
| Electron configuration | [Ar]4s1 3d10 |
| Atomic radius (van der Waals) | 140 pm |
| Oxidation states | +2, +1 |
| Physical state at 25 °C | solid |
| Family | transition metal |
| Group and period | 11 / 4 |
| Discoverer and year | known since antiquity |
Humanity has lived with copper since before chemistry existed as a science: there is no discoverer to record, only millennia of use.
Neighbours on the table
Horizontally, one proton less lands on Nickel (Z=28); one more lands on Zinc (Z=30). Vertically, group 11 gathers relatives with similar behaviour: Silver, Gold, Roentgenium.
The story behind the name
The symbol Cu comes from the Latin cuprum, a contraction of aes Cyprium, the metal of Cyprus, the island that supplied Rome with copper. It is the founding metal of metallurgy: hammered copper beads show up in archaeological sites 10,000 years old, and its alloy with tin opened the Bronze Age. A modern footnote: Chile, the biggest producer, digs up more copper in a year than the Roman Empire saw in its whole history. And copper is, with gold, one of only two metals with a colour of their own; every other metal is silvery.
Physical and chemical data: PubChem Periodic Table (NCBI, compiling NIST and IUPAC), public domain, snapshot of 2026-07-10. Temperatures converted from kelvin; historical notes cross checked against classic chemistry references.
Last updated: · Methodology and sources