Average mass of an atom in unified atomic mass units (1 u is 1/12 of the mass of a carbon-12 atom). Accounts for the natural mix of the element’s isotopes.
Number of the vertical column, 1 to 18 in IUPAC numbering. Elements in a group share the same outer-shell layout, so their properties are alike.
Number of the horizontal row. Usually equal to the number of electron shells in the atom; palladium is the exception, with four shells in period 5.
The subshell (s, p, d or f) that receives the last electrons in the usual filling order; it divides the table into four blocks. Real atoms sometimes differ: lanthanum starts the f-block but has no f electrons.
[Ar] 4s¹ 3d¹⁰
How electrons are arranged in subshells. The bracket stands for the previous noble gas; the superscript is the number of electrons in a subshell.
2, 8, 18, 1
Number of electrons in each shell, from the nucleus outwards.
1,084.6 °C (1,357.77 K)
Temperature at which the solid turns liquid at standard pressure. Helium, carbon and arsenic do not melt at normal pressure: helium needs about 25 atm, carbon and arsenic turn straight into vapour.
2,562 °C (2,835 K)
Temperature at which the liquid boils at standard pressure. For carbon and arsenic, the temperature at which the solid turns straight into vapour (sublimation).
8.933 g/cm³
Mass of one cubic centimetre of the substance. For gases, at 0 °C and standard pressure.
1.90 Pauling
How strongly an atom pulls electrons towards itself in a chemical bond. On the Pauling scale it runs from 0.79 for caesium to 3.98 for fluorine.
7.726 eV
Energy needed to remove the most loosely bound electron from an atom. The lower it is, the more easily the element gives up an electron, which is typical of metals.
1.236 eV
Energy released when a neutral atom gains an electron. Highest for the halogens. Noble gases, nitrogen and some metals form no stable negative ion.
132 pm
Half the length of a single covalent bond between two atoms of the element. It shows the size of an atom inside a molecule or crystal: 76 pm for carbon, 132 pm for iron.
+2, +1
Charges the atom would have in its compounds if all its bonds were ionic; the main ones are listed.
Copper (Cu) is a chemical element with atomic number 29. It sits in group 11 and period 4 of the periodic table, in the d-block. It is a transition metal. At room temperature it is a solid. Its standard atomic weight is 63.546.
Origin of the name
The Romans got much of their copper from Cyprus and called it aes cyprium, ‘metal of Cyprus’; in later Latin this became cuprum, which gave the symbol Cu and the English word copper. People have used copper since prehistoric times, so no one discovered it.
Where is copper found?
Copper is one of the few metals found in nature as lumps of pure metal, which is why it was among the first metals people used. Most of it, though, is mined from ores such as chalcopyrite and malachite. Chile is the world’s largest producer.
What is copper used for?
Copper conducts electricity better than any metal except silver, so most of it goes into electric wires and cables. It also makes water pipes and coins. Alloyed with tin it gives bronze, with zinc brass. Copper sulfate protects crops against fungi and keeps water free of algae.
Interesting facts
Bronze, made from copper and tin, was the first alloy people ever made on purpose; it was used for tools, weapons and vessels.
Copper roofs slowly turn from reddish brown to green: the metal becomes covered with a patina that protects it from further corrosion.