Valence Electrons

Electrons

• Electrons are found in orbitals within energy levels

• The regions in an atom where electrons are found are called orbitals

• Electrons usually occupy the lowest energy levels available in an atom

Valence electrons

• An electron in the outermost energy level of an atom is called a valence electron

• Ex.– The single electron of a hydrogen atom is a

valence electron because it is the only electron the atom has

– In a neon atom, its valence electrons are the eight electrons that are in the outermost energy level

Valence electrons

Chemical Reactivity

• The chemical reactivity of an atom is mainly determined by valence electrons

• Atoms with a complete (full) valence shell are not reactive

• Atoms with one or two valence electrons are highly reactive

• Orbitals that are empty, half-full, or full are more stable

Periodic Table