AP Bio Ch2 Electron Structure & Bonds

Electron shells

Levels of electrons at set distances from the nucleus.

Valence electrons

Electrons in the outermost shell.

Valence shell

Outermost electron shell.

Chemical bonds

Attractions between atoms that complete their outer shells.

Covalent bond

Strong bond formed by sharing electrons.

Molecule

Two or more atoms joined by covalent bonds.

Single bond

Sharing one pair of electrons between two atoms.

Double bond

Sharing two pairs of electrons between two atoms.

Valence

The bonding capacity of an atom.

Electronegativity

Atom’s ability to attract electrons in a bond.

Nonpolar covalent bond

Electrons shared equally.

Polar covalent bond

Electrons shared unequally, creating partial charges.

Ions

Atoms or groups with a net charge due to gained or lost electrons.

Cation

Positively charged ion.

Anion

Negatively charged ion.

Ionic bond

Attraction between oppositely charged ions.

Ionic compounds / Salts

Compounds formed by ionic bonds.

Hydrogen bond

Weak attraction between a hydrogen and an electronegative atom.

Van der Waals interactions

Weak attractions due to transient local charges.