Key Concepts in Chemistry: Valence Electrons and Bonds

valence electrons

Electrons in the outermost shell that determine an atom's chemical properties.

Lewis Dot Structure

A representation showing valence electrons as dots around an element's symbol.

Octet Rule

Atoms tend to have 8 valence electrons to achieve stability.

electronegativity

A measure of an atom's ability to attract electrons in a bond; helps determine polarity.

VSEPR model

A model used to predict molecular shape based on the number of electron pairs around the central atom.

polar molecule

A molecule with an uneven charge distribution.

nonpolar molecule

A molecule with evenly distributed charges.

dipole

An uneven distribution of charge indicated by δ⁺ and δ⁻.

energy in chemistry

The ability to cause change or motion, such as kinetic energy.

Kinetic Molecular Model

Explains that matter is made of tiny particles in motion, describing solids, liquids, and gases.

Intermolecular Forces of Attraction (IMFA)

Forces between neighboring particles of substances.

dipole-dipole forces

Attractions between polar molecules with permanent dipoles.

hydrogen bond

An attraction involving hydrogen and highly electronegative atoms like N, O, or F.

ion-dipole forces

Forces between ions and polar molecules (e.g., NaCl + H₂O).

London dispersion forces

Weak forces present in all molecules; dominant in nonpolar substances.

ionic bond

A metal and a nonmetal forming charged ions.

covalent bond

Two nonmetals sharing electrons.

polar covalent bond

A bond with unequal electron sharing, forming dipoles.

nonpolar covalent bond

A bond with equal sharing of electrons, with no dipole.