Valence, Lewis Structures, and Formal Charge (Chemistry)

Vocabulary flashcards covering valence concepts, Lewis structures, bond types, and formal charges based on the notes.

Valence

The combining capacity of an atom, typically the number of bonds it can form; related to the outermost electron shell.

Valence electrons

Electrons in the outermost shell that participate in bonding and determine an atom's bonding behavior.

Valence shell

The outermost electron shell of an atom where valence electrons reside.

Bond

A connection between atoms formed by sharing or transferring electrons; includes single, double, and triple bonds.

Bond order

The number of electron pairs shared between two atoms; indicates bond type (1 for single, 2 for double, 3 for triple).

Single bond

A bond formed by sharing one electron pair between atoms.

Double bond

A bond formed by sharing two electron pairs between atoms.

Triple bond

A bond formed by sharing three electron pairs between atoms.

Diatomic molecule

A molecule composed of two atoms of the same element, e.g., H2, O2, N2.

Lone pair

A pair of valence electrons that is not involved in bonding.

Octet rule

The guideline that most second-row elements prefer eight electrons around them in Lewis structures.

Lewis structure

A diagram showing the arrangement of atoms, bonds, and lone pairs using valence electrons.

Central atom

In a Lewis structure, the atom bonded to others; typically the least electronegative element and capable of forming multiple bonds; hydrogen is never central.

Covalent bond

A bond formed by sharing electrons between atoms in a molecule.

Polyatomic ion

A charged species composed of two or more atoms.

Electron counting for Lewis structures

A method where you sum the valence electrons of all atoms and divide by two to determine the number of electron pairs.

Octet rule for second-row elements

For elements like Li, Be, B, C, N, O, F, octets typically do not exceed eight valence electrons around the central atom.

Formal charge

The charge assigned to an atom in a Lewis structure, calculated as valence electrons minus nonbonding electrons minus half of bonding electrons.

Hydrogen’s placement in Lewis structures

Hydrogen forms only one bond and is never placed in the center of a Lewis structure.