Chemistry unit 2

Molecular Compounds

Composed of 2 or more nonmetals covalently bonded.

Molecule

Neutral group of atoms that act as a unit.

Ionic Compounds

Composed of oppositely charged ions held together by ionic bonds.

Ion

Atom that have non-equal #'s of protons and electrons.

Cation

Ion with a positive charge.

Anion

Ion with a negative charge.

Polyatomic Ion

Tightly bonded group of atoms that act as a unit and carry a charge.

Formula Unit

Lowest whole # ratio of ions in an ionic compound (neutral particle).

Chemical Formula

Shows the kinds and numbers of atoms in the smallest unit of a compound.

Binary Compound

Composed of 2 elements.

Ternary Compound

Composed of 3 or more elements (often contains a polyatomic ion).

Cross Over Method

For Ionic Compounds: the charge of one element or polyatomic ion crosses over to become the subscript of the other element.

Prefixes

Used in the name of the compound for Molecular Compounds (not including those beginning with H).

-ide Rule

For nonmetallic anions (the 2nd element in a binary compound) use an -ide ending.

Roman Numerals

For Group B (transition) metals with more than 1 ionic charge, a roman numeral must follow the name of the metal.

Ic above Ous Rule

Used for common transition metals with more than 1 ionic charge.

Ate above Ite Rule

Used for naming polyatomic ions containing Oxygen.

Binary Molecular Compounds

Only use prefixes in naming.

Subscript

Denotes the # of atoms of that element in a binary compound.