Bonding & Substance Properties (AQA GCSE Chemistry)

Boiling is when a liquid changes into a gas at a specific temperature.

Freezing is when a liquid changes into a solid.

Evaporation is when a liquid changes into a gas.

Condensation is when a gas changes into a liquid, usually on cooling.

Interconversion of state is the change of matter from one state to another due to changes in temperature or pressure.

The limitations of particle theory are:

• Does not account for forces of attraction between the particles

• Considers all particles as spherical in shape

• Does not consider the size of the particles

True.

The stronger the forces between the particles, the higher the energy needed for melting and boiling to occur.

The state of the substance at 40 ^oC is liquid.

The state of the substance at 10 ^oC is gaseous.

The state of the substance at 80 ^oC is solid.

The state of the substance at 100 ^oC is solid.

The state of the substance at -120 ^oC is gaseous.

The state of a substance at 1400 ^oC is liquid.

When a substance boils particles gain enough energy for the intermolecular forces to break and the molecules to escape from the surface of the liquid.

True.

Particle theory explains how matter changes state depending on the energy and forces present between the particles in the substance.

State symbols show which physical state each substance is in.

The state that is represented by (aq) is aqueous or in solution.

The state that is represented by (g) is gaseous.

The state that is represented by (l) is liquid.

The state that is represented by (s) is solid.

In the following equation carbon dioxide is in the gaseous state.

H₂SO₄ (aq) + CuCO₃ (aq) ⟶ CuSO₄ (aq) + H₂O (l) + CO₂ (g)

In the following equation sulfuric acid is in the aqueous state.

H₂SO₄ (aq) + CuCO₃ (aq) ⟶ CuSO₄ (aq) + H₂O (l) + CO₂ (g)

In the following equation water is in the liquid state.

2HCl (aq) + CuO (s) ⟶ CuCl₂ (aq) + H₂O (l)

In the following equation copper(II) is in the solid state.

2HCl (aq) + CuO (s) ⟶ CuCl₂ (aq) + H₂O (l)

Aqueous means dissolved in water.

Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.

True.

Ionic compounds have high melting and boiling points due to the strong electrostatic forces holding the ions together.

The structure of ionic compounds is called a giant ionic lattice.

Ionic compounds are usually solid at room temperature.

Electrostatic forces are the attractive (or repulsive) forces between charged particles.

An ionic compound conduct electricity when molten or in solution because the ions are free to move and carry a charge.

A giant ionic lattice is a series of positively charged and negatively charged ions arranged in an alternating pattern.

Ionic compounds have high melting points and high boiling point because:

• They have a giant structure

• Lots of energy is needed to overcome the strong electrostatic attraction between oppositely charged ions

In an ionic lattice, electrostatic forces act in all directions.

Solid ionic compounds not conduct electricity because the ions cannot move and carry a charge.

False.

Simple molecular structures have low melting and boiling points.

Covalent bonds are strong bonds that hold atoms together within a molecule, while intermolecular forces are weak attractive forces that exist between different molecules.

False.

Covalent compounds are poor conductors of electricity.

Simple molecular structures are small molecules with covalent bonds, which have weak forces between the molecules (intermolecular forces).

Covalent compounds are generally poor conductors of electricity because they do not contain free ions or electrons to carry the current.

False.

Intermolecular forces break when a covalent substance melts or boils..

As the relative molecular mass of a substance increases, the melting and boiling points also increase due to the increased number of electrons and stronger intermolecular forces.

Insulators are materials that do not allow the flow of electric charge or heat, and common insulators include plastics, rubber, and wood.

Simple molecular structures have low melting and boiling points due to weak intermolecular forces which require small amounts of energy to overcome.

True.

Simple molecular structures are often gases or liquids at room temperature.

A polymer is a substance consisting of very large molecules made by linking together large numbers of smaller molecules called monomers.

False.

Polymers are usually solid at room temperature due to larger intermolecular forces between polymer chains compared to simple molecules.

Covalent bonds link atoms in polymer molecules.

A monomer is a small molecule that can be bonded to other identical molecules to form a polymer.

Intermolecular forces are between the polymer chains.

Giant covalent structures are solids with high melting points, consisting of a huge number of non-metal atoms bonded to other non-metal atoms via strong covalent bonds.

True.

Giant covalent structures are also called giant lattices.

This giant covalent structure is graphite.

Three examples of giant covalent structures are diamond, graphite, and silicon dioxide.

Giant covalent structures have high melting points because there are many strong covalent bonds between atoms which require lots of energy to overcome.

This giant covalent structure is diamond.

Diamond and graphite are made from carbon atoms.

Silicon dioxide (silica) is made from silicon and oxygen.

False.

Giant covalent structures are solids at room temperature.

False.

Giant covalent structures have a fixed ratio of atoms in the overall structure.

This giant covalent structure is silicon dioxide.

An alloy is a mixture of metals, where the metals are mixed together physically but are not chemically combined.

Advantages of using alloys over pure metals are:

• Greater strength

• Greater hardness

• Increased resistance to corrosion

• Increased resistance to extreme temperatures

True.

Alloys can also be made from metals mixed with non-metals such as carbon.

Alloys contain atoms of different sizes which distort the regular arrangement of atoms.

The increased hardness and strength of an alloy is caused by the different size atoms which distort the regular arrangements of atoms, preventing the layers of atoms from sliding over each other easily.

False.

Alloys are physical mixtures of metals, where the metals are not chemically combined.

Alloys often have greater strength / hardness, or resistance to corrosion / extreme temperatures compared to pure metals.

Metals generally have high melting points because:

• They have giant structures

• There are strong electrostatic forces of attraction between the positive metal ions and the negative delocalised electrons

• These forces need lots of energy to break

Metals are malleable because the atoms are arranged in layers which can slide over each when force is applied.

True.

Alloys contain atoms of different sizes so the layers become distorted .

True.

Metals are good conductors of heat and electricity.

The metallic bond is the strong force of attraction between the positive metal ions and the delocalised electrons in a metal structure.

Metals can conduct heat as the delocalised electrons are free to move and transfer thermal energy through the structure

False.

Some metals are better conductors of heat than others.

Metals conduct electricity because the delocalised electrons are able to move through the structure and carry a charge.

False.

The metallic bond is the strong force of attraction between the positive metal ions and the delocalised electrons