Chemistry: Polyatomic Ions, Atomic Mass, and Percent Composition

Vocabulary flashcards derived from the lecture notes, covering polyatomic ions, ionic naming, oxidation states, and mass/percent composition concepts.

Polyatomic ion

A covalently bonded group of atoms that carries a net charge and forms ionic compounds.

Ammonium ion

NH4+; a positively charged polyatomic ion commonly found as a cation in salts.

Acetate ion (C2H3O2-)

CH3COO-; a negatively charged polyatomic ion derived from acetic acid.

Nitrate ion (NO3-)

NO3-; polyatomic ion with three oxygens.

Nitrite ion (NO2-)

NO2-; polyatomic ion with two oxygens.

Sulfate ion (SO4^2-)

SO4^2-; polyatomic ion with four oxygens carrying a -2 charge.

Sulfite ion (SO3^2-)

SO3^2-; polyatomic ion with three oxygens carrying a -2 charge.

Carbonate ion (CO3^2-)

CO3^2-; polyatomic ion with three oxygens, -2 charge.

Phosphate ion (PO4^3-)

PO4^3-; polyatomic ion with four oxygens, -3 charge.

Phosphite ion (PO3^3-)

PO3^3-; polyatomic ion with three oxygens, -3 charge.

Hydroxide ion (OH-)

OH-; the hydroxide ion, a basic species that carries a -1 charge.

Iron(II) hydroxide

Fe(OH)2; iron in the +2 oxidation state with two hydroxide ligands.

Roman numeral naming (oxidation state)

A convention to indicate the metal's oxidation state in a compound (e.g., iron(II) vs iron(III)) when charges vary.

Average atomic mass

The weighted average mass of an element's isotopes, calculated as the sum of (fractional abundance × isotope mass); expressed in amu or grams per mole.

Percent composition

Mass percent of an element in a compound; calculated as (mass of element in sample / molar mass of compound) × 100.