Week 4 Chemistry: Covalent & Ionic Bonding, Lewis Structures, and Nomenclature

Vocabulary flashcards covering key terms from Week 4 notes on covalent and ionic bonding, naming, Lewis structures, polyatomic ions, and VSEPR geometry.

Ionic bond

Electrostatic attraction between oppositely charged ions formed by transfer of electrons from a metal to a nonmetal.

Covalent bond

Bond formed when nonmetal atoms share valence electrons; typically between nonmetals (includes boron); follows the Octet Rule.

Molecule

Two or more atoms held together by covalent bonds.

Octet Rule

Atoms tend to have eight valence electrons (two for hydrogen) to achieve stability.

Hydrogen duet

Hydrogen achieves a full outer shell with 2 electrons.

Lone pair

A pair of valence electrons not involved in bonding.

Lewis structure

A diagram showing atoms, valence electrons, bonds, and lone pairs.

Total valence electrons (TVE)

Sum of valence electrons from all atoms in the molecule.

Bond

A shared or transferred pair of electrons linking atoms.

Single bond

A covalent bond with two electrons shared (one line).

Double bond

A covalent bond with four electrons shared (two lines).

Triple bond

A covalent bond with six electrons shared (three lines).

Expanded octet

Atoms in periods 3 or higher can have more than eight electrons around the central atom (e.g., S, P, Cl) in certain molecules or ions.

Dinitrogen pentoxide

N2O5; a binary molecule naming example: two nitrogens and five oxygens.

Carbon disulfide

CS2; a binary molecule naming example: carbon bonded to two sulfurs.

Binary molecular compound naming

Naming for two nonmetals; use prefixes to show numbers; second element ends with -ide.

Prefixes

Mono-, di-, tri-, tetra-, penta-, hexA-, etc.; indicate the number of atoms in a molecule.

Mono omission rule

Do not use the mono prefix for the first element if only one is present; also apply vowel-omission rules when vowels meet.

-ide suffix

The second element in a binary compound ends in -ide.

Di­­atomic molecule

A molecule consisting of two atoms of the same element (e.g., O2); name is just the element.

Ammonium ion

NH4+; a polyatomic cation; a special case in ionic naming.

Roman numeral (in naming)

A numeral indicating the metal’s oxidation state/charge in ionic compounds with variable charge.

Ionic naming rules

Name the metal (or ammonium) cation first, then the anion; ammonium is treated as a cation.

Covalent naming rules

Name nonmetals using prefixes; second element ends with -ide; check exceptions (e.g., B, Si).

Flowchart for naming

A stepwise method to decide ionic vs molecular and apply the appropriate naming rules.

Polyatomic ion

A group of covalently bonded atoms with an overall charge (e.g., SO4^2-, NH4+).

Brackets for polyatomic ions

When drawing, enclose the polyatomic ion in brackets with the overall charge outside.

Formal charge

A bookkeeping tool to help assess correctness; not the actual charge; aim to minimize it.

VSEPR theory

Valence-shell electron-pair repulsion; electron groups repel to predict molecular geometry.

Electron dense area

An electron group around the central atom (single/double/triple bond or lone pair) that influences shape.

Molecular geometry

The 3D arrangement of atoms in a molecule, determined by VSEPR shapes.

Central atom

The atom placed at the center of the Lewis structure skeleton (often the first element in the formula; commonly C, N, or P).

Skeleton structure

Initial arrangement of atoms in a Lewis structure before octet completion.

Bond angle

The angle between adjacent bonds in a molecule (e.g., ~109° in tetrahedral, ~120° in trigonal planar).