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
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