chemistry formulas

ammonium

NH₄⁺

sulfate

SO₄²⁻

sulfite

SO₃²⁻

hydroxide

OH⁻

carbonate

CO₃²⁻

nitrate

NO₃⁻

nitrite

NO₂⁻

phosphate

PO₄³⁻

phosphite

PO₃³⁻

chloride

Cl⁻

chlorite

ClO₂⁻

chlorate

ClO₃⁻

permanganate

MnO₄⁻

thiosulfate

S₂O₃²⁻

rule

“-ate” ions have more oxygen atoms, while “-ite” ions have fewer oxygen atoms

“-ide” ions is just the element with a charge - no oxygen atoms attached

dichromate

Cr₂O₇²⁻

acetate

CH₃COO⁻

chromate

CrO₄²⁻

hydrogen phosphate

HPO₄²⁻

atom

the smallest unit of matter

isotope

atoms of the same element with the same number of protons but different numbers of neutrons

element

pure substance made up of only one type of atom

compound

substance made of two or more different elements chemically bonded

molecule

two or more atoms bonded together - either the same or different

elemental molecule

a molecule made of only one element

ground state

when electrons are in the lowest-energy shells following the normal filling order

excited state

when electrons have absorbed energy and moved to a higher-energy shell than normal

ion

an atom (or molecule) that does not have an equal number of protons and electrons giving it an overall positive or negative charge

cation

an atom that has lost one or more electrons - giving it an overall positive charge due to protons > electrons

anion

an atom that has gained one or more electrons - giving it an overall negative charge due to protons < electrons

monoatomic ions

also called simple ions are made form one atom (e.g, chloride, Cl⁻)

polyatomic ions

made from a group of atoms bonded together (e.g. hydroxide, OH⁻ )

ionic bond

the electrostatic attraction between a positive metal ion and a negative non-metal ion

ionic compound

forms when metal cations and non‑metal anions bond in fixed, charge‑balanced ratios