• Starter- Copy the paragraph (Correct the mistakes)

• Ionic substances have low melting points and high boiling points. This is because they are held together in the lattice by very weak electrostatic forces. Not much energy is needed to break these bonds. Ionic substances do not conduct electricity when they are solid because the ions are not held together in a lattice. They do conduct electricity when they are molten or dissolved n water, because charged particles are free to move around.

• Ionic substances have high melting points and high boiling points. This is because they are held together in the lattice by very strong electrostatic forces. A lot of energy is needed to break these bonds. Ionic substances do not conduct electricity when they are solid because the ions are held together in a lattice. They do conduct electricity when they are molten or dissolved n water, because charged particles are free to move around.

What is an ionic lattice?In an ionic compound, millions and millions of ions are packed together in a regular cubic arrangement, joined by ionic bonds.

The structure of the ionic lattice affects the properties of the ionic compound.

The ionic lattice will continue to build in this way until there are no more ions left to add.

This forms a giant 3D structure called an ionic lattice.

Heating ionic compoundsWhy are ionic compounds solid at room temperature and have high melting points and boiling points?

Larger ionic charges produce stronger ionic bonds and so much more heat is required to break the ionic bonds in magnesium oxide than in sodium chloride.

sodium chloride

magnesium oxide

CompoundIon charges Melting point

(oC)Boiling point (oC)

1+ and 1-

2+ and 2-

801 1,413

2,852 3,600

strong ionic bonds hold

ions together

Ionic bonds are strong and a lot of heat is needed to break them.

How can ionic compounds conduct electricity?

When liquid (molten), the ions can break free of the lattice and are able to move. The ions are charged particles and so can carry an electric current.

As solids, ionic compounds cannot conduct electricity because their ions are bonded together in the lattice.

ions in solid state

cannot move

ions in molten state

can move and conduct

electricity

Ionic compounds are usually soluble in water because water molecules have a slight electrical charge and so can attract the ions away from the lattice. When dissolved, the ions are free to move and can carry an electric current.

Solubility

What is a salt?

• An ionic compound formed between a metal and non-metal is called a salt.

Solubility

• If a substance dissolves well in a particular liquid, we say that it is soluble.

• If a substance does not dissolve at all in a particular liquid we say that it is insoluble.

The Rules

Precipitates

• A reaction in which an insoluble solid is produced from two soluble substances is called a precipitation reaction.

• It happens if the reactants are soluble and at least one of the products is insoluble but not if all the products are soluble.

1.Sodium hydroxide + barium chloride ___________________________

2.Silver nitrate + potassium chloride ___________________________

3.Barium chloride + sodium sulphate ___________________________

Task- Write down the products and from the table decide which ones are soluble and which are insoluble.

1.Sodium hydroxide + barium chloride ___________________________

2.Silver nitrate + potassium chloride ___________________________

3.Barium chloride + sodium sulphate ___________________________

1. Sodium Chloride + Barium Hydroxide are the two products. Barium Hydroxide is the precipitate because it is insoluble.

2. Silver Chloride + Potassium Nitrate are the two products. Silver Chloride is the precipitate because it is insoluble.

3. Barium Sulphate and Sodium Chloride are the two products. Barium Sulphate is the precipitate because it is insoluble.