Electron in the Outermost shell of electrons in an atom in its ground state. Click on Term to Read More of an atom, or the Charge on an ion reflecting gained or lost electrons. For example, an iron atom that has lost two electron, Fe2+, is described as having a valence of 2. Typical valences in geological materials are shown below. band of a solid. Valence electrons are more active than non-valence electrons, so valence electrons are responsible for most of an atom’s or solid’s electrical and chemical properties.