Lewis Structures and Molecular Geometry

Flashcards for key vocabulary and concepts related to Lewis Structures, Electronegativity, Electron Affinity, Formal Charge, Resonance, and VSEPR Theory.

Lewis Structure

A representation of covalent compounds showing chemical formulas and arrangements of atoms, such as in ethanol (C2H6O or CH3CH2OH).

Electronegativity

A measure of an atom's ability to attract shared electrons in a chemical bond, often measured on the Pauling scale.

Electron Affinity

The amount of energy released or absorbed when an atom gains an electron in the gas phase to form a negative ion, measured in kJ/mol.

Valence Electrons

Electrons in the outermost shell of an atom that participate in chemical bonding.

Central Atom Selection

In Lewis structures, the central atom is typically the least electronegative element (excluding hydrogen).

Octet Rule

The principle that atoms in a molecule tend to achieve a stable electron configuration with eight valence electrons (or two for hydrogen).

Formal Charge

A bookkeeping tool to estimate the charge on an atom in a Lewis structure, assuming equal sharing of bonding electrons.

Formal Charge Formula

Formal Charge = (Valence Electrons) - (Nonbonding Electrons) - 1/2 (Bonding Electrons)

Resonance

A condition where multiple valid Lewis structures can be drawn for a molecule or ion, with the true structure being a hybrid of these structures.

VSEPR Theory

Valence Shell Electron Pair Repulsion theory, which predicts the shape of molecules based on the repulsion of electron groups around a central atom.

Electron Group

Can be a single bond, double bond, triple bond, or a lone pair of electrons.

Common Molecular Shapes

Include linear, trigonal planar, bent, tetrahedral, trigonal pyramidal, see-saw, T-shaped, square planar, square pyramidal, and octahedral, determined by the number of electron groups and lone pairs.