Year 9 Science- Chemistry

Ions

Atoms or molecules that have gained or lost electrons, resulting in a net electrical charge. Can be positive (cations) or negative (anions).

Compounds

Substances formed from two or more different elements chemically bonded together in a fixed ratio. These bonds can be ionic or covalent.

Molecules

Electrically neutral group of two or more atoms held together by chemical bonds. Molecules can be formed from the same element or different elements.

Atomic Mass

The mass of an atom, typically expressed in atomic mass units (amu). It is approximately equivalent to the number of protons plus the number of neutrons in the nucleus.