GCSE Chemistry - Formation of Ions - Electrons | Charge | Equations (2026/27 exams)

What are Ions?00:00:07

An ion is a charged particle, which can be a single atom or a group of atoms. Ions are formed when atoms gain or lose electrons to achieve a stable, full outer electron shell, making them more stable.

Periodic Table and Ion Formation00:00:42

The group number on the periodic table indicates the number of electrons in an atom's outermost shell. Atoms that need to lose or gain only one or two electrons (Groups 1, 2, 6, 7) are more likely to form ions because it requires less energy. Atoms in Groups 3, 4, and 5 typically do not form ions as readily due to the high energy cost of losing or gaining multiple electrons.

Writing Ion Formation Equations00:02:13

Chemical equations can illustrate the gain or loss of electrons. If an atom loses electrons to become a positive ion, the electrons are placed on the right side of the equation. If an atom gains electrons to become a negative ion, the electrons are placed on the left side of the equation, showing they combine with the atom. Atoms can lose or gain multiple electrons, as seen with magnesium (losing two) or oxygen (gaining two).