Chemistry Grade 10 Term 1 2026

Atom

The smallest particle of an element that retains its identity in a chemical reaction.

Molecule

A neutral group of non-metal atoms covalently bonded.

Element

A substance that is made up of one type of atom, defined by its atomic number.

Compound

A substance that is made up of atoms of different elements joined together by chemical bonds in a fixed ratio.

Atomic number

The number of protons in the nucleus of an atom of an element.

Mass number

The total number of protons and neutrons in the nucleus of an atom.

Ion

An atom or molecule that has gained or lost one or more electrons and is charged.

Polyatomic ion

A tightly bound group of atoms that behaves as a unit and has a positive or negative charge.

Difference between an atom and an ion

Atoms are neutral particles with equal protons and electrons, forming the basic units of matter whereas ions are atoms that have lost or gained electrons, resulting in an electrical charge

Acid

It is a substance that dissociates to form hydrogen ions in solution

Base

It is a substance that reacts with an acid to form salt and water only

Alkali

When in a solution, an alkali produces hydroxide ions

Precipitate

An insoluble solid formed when two soluble ionic solutions react

Saturated molecules

only has single carbon-carbon bonds

Unsaturated molecules

has one or more double or triple carbon-carbon bonds

Saturated solution

maximum amount of solute for a given volume of solvent

Unsaturated solution

Less solute than a saturated solution

Supersaturated solution

contains more solute than it can theoretically hold

Concentrated solution

has a large mass of solute dissolved in a given amount of solvent

Diluted solution

has a small mass dissolved in a given volume of solvent

Homologous series

a class of molecules in which each member differs by -CH2 from the previous member