Ionic bonding and structure

What is ionic bonding?

Ionic bonding is the transfer of electrons from a metal to a non-metal, forming positively charged cations and negatively charged anions.

What do dot-and-cross diagrams show in ionic bonding?

They visualise the transfer of electrons, the formation of ions with full outer shells, and their noble-gas electronic configurations.

How do metals form cations?

Metals lose electrons from their outer shell, forming positively charged ions with stable noble gas configurations.

Give an example of cation formation in lithium.

Lithium loses one electron → Li⁺ with configuration 1s² (same as helium).

Give an example of cation formation in calcium.

Calcium loses two electrons → Ca²⁺ with configuration 1s² 2s² 2p⁶ 3s² 3p⁶ (same as argon).

Give an example of cation formation in aluminium.

Aluminium loses three electrons → Al³⁺ with configuration 1s² 2s² 2p⁶ (same as neon).

How do non-metals form anions?

Non-metals gain electrons into their outer shell, forming negatively charged ions.

Give an example of anion formation in oxygen.

Oxygen gains 2 electrons → O²⁻ with configuration 1s² 2s² 2p⁶ (same as neon).

What is an ionic bond?

An ionic bond is the strong electrostatic attraction between oppositely charged cations and anions.

Why is ionic bonding non-directional?

Because the electrostatic attraction acts in all directions throughout the lattice.

Why do ionic compounds have high melting points?

Strong electrostatic forces between ions require large amounts of energy to overcome.

What structure do ionic compounds form?

A giant ionic lattice – a 3D repeating network of alternating cations and anions.

What determines the shape of the lattice?

The relative sizes of the ions. (e.g., NaCl and MgO have cubic lattices).

Why are most ionic compounds solid at room temperature?

Strong ionic bonds require lots of energy to break, so they remain solid.

How does ionic charge affect melting points?

Higher ionic charge = stronger electrostatic attraction = higher melting points.

Why are many ionic compounds soluble in water?

Polar water molecules break down the lattice and surround ions (δ⁺ attracts anions, δ⁻ attracts cations).

What factors affect solubility of ionic compounds?

Balance between ionic bond strength and ion–solvent attraction.

General rule for ionic charge and solubility?

Higher ionic charge → lower solubility (though with exceptions).

Why don’t ionic compounds conduct electricity when solid?

Ions are fixed in place within the lattice, so no mobile charge carriers.

Why do ionic compounds conduct when molten or aqueous?

The lattice breaks down, ions become free to move, and can carry charge.