Chemistry Vocabulary: Reactions, Formulae, and Periodic Table Concepts

Vocabulary flashcards covering key terms from reactions, formula writing, balancing, and periodic table concepts.

Ion

An electrically charged particle formed when atoms gain or lose electrons.

Cation

A positively charged ion formed when an atom loses electrons.

Anion

A negatively charged ion formed when an atom gains electrons.

Valency

The combining power of an element, often equal to the number of electrons it needs to gain or lose to achieve a stable configuration.

Oxidation state

The hypothetical charge of an atom in a compound, indicated by numbers (often Roman numerals) showing electron gain or loss.

Noble gas configuration

A stable outer electron arrangement (typically 2, 8, 8, …) that atoms strive to achieve.

Electron configuration

The arrangement of electrons in an atom's electron shells.

Ionization energy

The energy required to remove the outermost electron from a gaseous atom to form a cation.

Electron affinity

The energy change when an electron is added to a neutral atom to form an anion; often energy released.

Polyatomic ion

A group of covalently bonded atoms that carries an overall charge (e.g., carbonate, sulfate, nitrate).

Salt

An ionic compound formed from a reaction between an acid and a base; composed of a cation and an anion.

Chemical formula

A notation that shows the types and numbers of atoms in a molecule or compound.

Empirical formula

The simplest whole-number ratio of atoms in a compound.

Reactants

Substances present at the left side of a chemical equation that undergo change.

Products

Substances formed at the right side of a chemical equation.

State symbols

Symbols (s), (l), (g), (aq) indicating solid, liquid, gas, or aqueous states in a chemical equation.

Balanced chemical equation

A chemical equation in which the number of atoms of each element is the same on both sides.

Copper(II) oxide

CuO, a compound where copper has oxidation state +2.

Calcium oxide

CaO, a basic oxide formed by heating calcium carbonate.

Calcium hydroxide

Ca(OH)2, also known as lime; product of CaO reacting with water.

Sodium hydroxide

NaOH, a strong base.

Ammonium nitrate

NH4NO3, a salt formed from ammonia and nitric acid.

Lead carbonate

PbCO3, a carbonate salt.

Lead chloride

PbCl2, a chloride salt of lead(II).

Zinc carbonate

ZnCO3, a carbonate salt.

Magnesium nitride

Mg3N2, a nitride of magnesium; reacts with water to form Mg(OH)2 and NH3.

Sodium carbonate

Na2CO3, also called washing soda; a carbonate salt.

Calcium carbonate

CaCO3, a common carbonate mineral; reacts with acids to release CO2.

Acid–base neutralization

Reaction between an acid and a base to form a salt and water.

Isotope

Atoms of the same element with the same atomic number but different mass numbers.

Atomic number

Number of protons in the nucleus; defines the identity of an element.

Mass number

Total number of protons and neutrons in the nucleus of an atom.

Period

A horizontal row in the periodic table; elements in the same period have the same number of electron shells.

Group

A vertical column in the periodic table; elements in the same group have similar valence electron configurations.

Transition metal

Elements in the d-block of the periodic table known for variable oxidation states.