What is the valency of copper?
Copper is one of the transition elements and thus exhibits variable oxidation states. It has two valencies: +1 and +2 and the corresponding atoms are termed as Cuperous (+1 valency) and Cupric (+2 valency). These are also denoted as Cu(I) and Cu(II).
Copper has an atomic number of 29 and its electronic configuration is 1s2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s1. According to Aufbau Principle, 4s orbital is filled before 3d orbital and hence, the last electron (in case of copper) fills the 3d orbital. This gives the copper atom a choice to lose either 1 electron from 4s orbital to achieve fully filled 3d orbital or lose 1 electron each from 4s and 3d orbitals. In first scenario, we end up with cuperous or Cu(I) and in the second case, we have Cu(II), that is, +2 valency.
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