How many valence electrons does a copper atom have?

A copper atom has one valence electron, which is primarily responsible for its chemical properties and behavior in bonding. Copper, with the atomic number 29, has an electron configuration of [Ar] 3d^10 4s^1. In this configuration, the 4s subshell contains one electron that is involved in bonding and can be lost or shared in chemical reactions.

Understanding that the valence electrons are the outermost electrons in an atom that participate in chemical bonding is crucial. In the case of copper, the presence of just one electron in the outermost shell contributes to its conductivity and makes it a good conductor of electricity and heat. This single valence electron allows for a variety of oxidation states, including +1 and +2, which are significant in copper's various compounds and reactions in different environments.