Silver has to give up one electron. Silver has ten electons in the 4d orbital and one electron in the 5s orbital. Atoms achieve stability when they have full orbitals. The 4d orbital can hold a maximum of ten electrons since there are 5 suborbitals in it. Therefore, when one electron is lost from the 5s orbital silver would have a full last orbital of 10 electrons in its 4d orbital, giving it its most stable configuration.