6.4 - Lewis Structures

valence electron (revisited)

an atom's outermost electrons, and/or any of an atom's electrons that participate in bond formation

core electron

any of an atom's inner electrons that does not participate in forming a chemical bond, making it not a valence electron

Lewis structure

a diagram that identifies a molecule's structure, using dots for nonbonding valence electrons and lines for bonding pairs

valency

describes an atom's combining power in terms of how many bonds it needs to form

lone pair

a pair of valence-shell electrons that are not involved in bonding and that belong exclusively to one atom

duet rule

the observational rule of thumb that the valence shells of hydrogen and helium hold a maximum of two electrons

octet rule

the observational rule of thumb that the valence shells of the main-group elements seek to contain at least eight electrons, except for beryllium, boron and aluminum, which can contain fewer

hypervalent molecule (expanded octet)

an exception to the octet rule that permits atoms in the third row or lower on the periodic table to have more than eight electrons when they are the central atom, because of available and empty d orbitals

resonance structures

two or more alternate, but equivalent, Lewis structures for the same molecule that each show an an acceptable location for a required double bond

delocalized electrons

bonding electrons that are free to move about the valence shells of three or more atoms, making a bond distributed over more than two atoms

resonance hybrid

the true bonding structure of a molecule that incorporates contributions from each resonance structure, requiring a delocalized bond