Inorganic Chemistry

What happens to the atomic radius down Group 2?

It increases because extra electron shells are added.

What happens to first ionisation energy down Group 2? Why?

It decreases due to increased atomic radius and shielding.

Describe the trend in reactivity of Group 2 metals with water.

Reactivity increases down the group.

Write the ionic equation for the reaction of calcium with water.

Ca(s) + 2H₂O(l) → Ca²⁺(aq) + 2OH⁻(aq) + H₂(g)

What are Group 2 hydroxides used for?

Neutralising acids; e.g. Ca(OH)₂ in agriculture.

What happens to boiling points down Group 7?

Increases due to stronger van der Waals forces.

What happens to reactivity down Group 7?

Decreases because it becomes harder to gain an electron.

What is a displacement reaction?

A more reactive halogen displaces a less reactive halide from solution.

What colour change is observed when Cl₂ displaces Br⁻?

Orange solution (Br₂ formed).

Write the ionic equation for Cl₂ displacing I⁻.

Cl₂ + 2I⁻ → 2Cl⁻ + I₂

How do you test for sulfate ions?

Add HCl and BaCl₂ → white precipitate of BaSO₄ forms.

What is the test for ammonium ions?

Add NaOH and warm → ammonia gas (NH₃) turns red litmus blue.

What order do you carry out anion tests?

Carbonate → Sulfate → Halide

Why must you add acid before testing for carbonates?

To ensure CO₃²⁻ reacts to form CO₂ gas.

Define a transition metal.

A d-block element that forms at least one ion with an incomplete d-subshell.

Why is Sc not a transition metal?

Sc³⁺ has an empty d-subshell.

What are the common oxidation states of Mn and Fe?

Mn: +2, +4, +7; Fe: +2, +3

What is a ligand?

An ion/molecule that donates a lone pair of electrons to a metal ion.

What is the shape of a complex ion with 6 ligands?

Octahedral (90° angles).

Name a bidentate ligand.

Ethane-1,2-diamine (en) or ethanedioate ion.

What does a more positive electrode potential indicate?

A greater tendency to be reduced (gain electrons).

What is the standard hydrogen electrode used for?

A reference electrode with E° = 0.00 V.

How is a salt bridge used in a cell?

It completes the circuit and allows ion flow to maintain charge balance.

How do you predict feasibility using E° values?

More positive E° = species reduced; more negative E° = species oxidised.