Study Guide on Ions for GCSE Chemistry

What is an Ion?

An atom or a molecule that has a net electrical charge due to the loss or gain of one or more electrons.

Cations

Positively charged ions that are formed by the loss of electrons.

Examples of Cations

Na⁺, Ca²⁺, Al³⁺

Anions

Negatively charged ions that are formed by the gain of electrons.

Examples of Anions

Cl⁻, O²⁻, SO₄²⁻

Ionization

The process of forming ions through the loss or gain of electrons.

Alkali Metals (Group 1)

Form +1 cations (e.g., Li⁺, Na⁺, K⁺).

Alkaline Earth Metals (Group 2)

Form +2 cations (e.g., Mg²⁺, Ca²⁺).

Halogens (Group 17)

Form -1 anions (e.g., F⁻, Cl⁻, Br⁻).

Noble Gases

Generally unreactive and do not form ions.

What are Ionic Compounds?

Compounds formed when cations and anions bond together through ionic bonds to create neutral compounds.

Common examples of Ionic Compounds

NaCl (sodium chloride), MgO (magnesium oxide), CaF₂ (calcium fluoride).

Naming Cations

Cations are named after the element, followed by the word 'ion' (e.g., sodium ion).

Naming Anions

Anions are typically named by taking the root of the element's name and adding '-ide' or '-ate' for polyatomic ions (e.g., chloride for Cl⁻, sulfate for SO₄²⁻).

Importance of Ions

Ions play a crucial role in chemical reactions, electrical conductivity in solutions, and biological processes.

What does NaCl represent?

One sodium ion (Na⁺) for every chloride ion (Cl⁻).

What does MgO represent?

One magnesium ion (Mg²⁺) paired with one oxide ion (O²⁻).

What does CaF₂ represent?

One calcium ion (Ca²⁺) bonding with two fluoride ions (F⁻) to achieve electrical neutrality.