1.3 - Structure + Properties of Ionic Compounds

What is an ionic substance?

A substance made of oppositely charged ions held in a fixed position by strong ionic bonds, held together in a giant ionic lattice

What is an ionic latice?

In an ionic compound, millions of ions are packed together in a regular cubic arrangement, joined by ionic bonds. This forms a giant 3D structure called an ionic lattice?

How long will an ionic latice continue to build itself?

until there are no more ions left to add

What does giant mean in regards to ionic substances?

very large structure

What is lattice?

regular repeating arrangement

How are these ions held together in their lattices?

some ions are negatively charged and some are postively charged, opposite charges attract holding them together

What are the properties of ionic compounds?

• ionic compounds have very high melting and boiling points

• can conduting electricity but not in a solid form

• ionic compounds are brittle

• soluble in water

Why do ionic compounds have very high melting and boiling points?

They form giant lattice structures that are held together by strong electrostatic forces which require large amounts of energy to break. The more energy needed to overcome a force of attraction the higher the melting and boiling points are.

What is an example of an ionic compound having a high or low melting and boiling point?

Sodium chloride has 1⁺ and 1^- ions while magnesium oxide has 2⁺ and 2^-. There is a larger attraction between the stronger charges of MgO, so more energy is needed. Therefore magnesium oxide has an even higher melting and boiling point

What is needed for a substance to conduct electricity?

charged particles that are free to move and carry the charge

Why can’t solid ionic compounds conduct electricity?

no movement of ions as atoms in a solid state cannot move and movement is needed to conduct electricity

Why can molten/dissolved in water ionic compounds conduct electricity?

the ions are free to move and carry a charge

Why are ionic compounds brittle?

Ions with the same charges are lined up together, so when a force is applied they slide against each other and snap