On the periodic table, copper has the electron configuration [Ar] 3d10 4s1.
Copper has atomic number 29 and is a transition metal. Its configuration is often taught as an exception to a simple filling pattern because a completely filled 3d subshell is especially stable, leaving one electron in the 4s orbital.
Copper’s symbol Cu comes from the Latin cuprum, referring to the island of Cyprus, an important ancient source of the metal. Humans have used copper for thousands of years, including in tools, ornaments, coins, and bronze alloys.
Silver also has a filled d subshell and one s electron, but its configuration is [Kr] 4d10 5s1. Zinc has [Ar] 3d10 4s2, so these nearby elements are common sources of confusion.