4.2.2 How bonding and structure are related to the properties of substances

Question 1

What are the three states of matter?

Answer 1

Solid, liquid, and gas.

Question 2

At what points do melting, freezing, boiling, and condensing occur?

Answer 2

Melting and freezing occur at the melting point. Boiling and condensing occur at the boiling point.

Question 3

How are particles represented in the simple model of matter?

Answer 3

Particles are represented as small, solid spheres.

Question 4

What does the amount of energy needed for a state change depend on?

Answer 4

It depends on the strength of the forces between particles.

Question 5

What happens to the melting and boiling points if the forces between particles are stronger?

Answer 5

The melting and boiling points are higher.

Question 6

(HT only) What are the limitations of the simple model of matter?

Answer 6

It does not show forces between particles. Particles are represented as solid, inelastic spheres. The model does not accurately depict particle interactions.

Question 7

What are the state symbols in chemical equations?

Answer 7

(s) = Solid
(l) = Liquid
(g) = Gas
(aq) = Aqueous solution

Question 8

Why are state symbols used in chemical equations?

Answer 8

To show the states of matter for substances involved in a reaction.

Question 9

What is the structure of ionic compounds?

Answer 9

They have a regular giant ionic lattice.

Question 10

Why do ionic compounds have high melting and boiling points?

Answer 10

Because of the strong electrostatic forces of attraction between oppositely charged ions, which require a lot of energy to break.

Question 11

When do ionic compounds conduct electricity?

Answer 11

When they are molten or dissolved in water, as the ions are free to move.

Question 12

What are the states of substances made of small molecules?

Answer 12

They are usually gases or liquids with relatively low melting and boiling points.

Question 13

What forces are overcome during melting or boiling of small molecules?

Answer 13

Weak intermolecular forces, not covalent bonds.

Question 14

How do intermolecular forces change with molecule size?

Answer 14

Larger molecules have stronger intermolecular forces, leading to higher melting and boiling points.

Question 15

Why don’t substances made of small molecules conduct electricity?

Answer 15

Because their molecules do not have an overall electric charge.

Question 16

What is the structure of polymers?

Answer 16

They consist of very large molecules with atoms linked by strong covalent bonds.

Question 17

Why are polymers solid at room temperature?

Answer 17

Because the intermolecular forces between polymer molecules are relatively strong.

Question 18

How can polymers be identified?

Answer 18

By diagrams showing their bonding and structure.

Question 19

What are giant covalent structures?

Answer 19

Solids with very high melting points where all atoms are linked by strong covalent bonds.

Question 20

What are examples of giant covalent structures?

Answer 20

Diamond, graphite, and silicon dioxide.

Question 21

What needs to be overcome to melt or boil substances with giant covalent structures?

Answer 21

The strong covalent bonds between atoms.

Question 22

How can giant covalent structures be recognized?

Answer 22

From diagrams showing their bonding and structure.

Question 23

What is the structure of metals?

Answer 23

Metals have a giant structure with strong metallic bonding.

Question 24

Why do metals have high melting and boiling points?

Answer 24

Due to the strong metallic bonds.

Question 25

Why can metals be bent and shaped?

Answer 25

Because their atoms are arranged in layers that can slide over each other.

Question 26

Why are alloys harder than pure metals?

Answer 26

The layers of atoms are distorted, preventing them from sliding over each other easily.

Question 27

Why are metals good conductors of electricity?

Answer 27

Because delocalized electrons can carry electrical charge through the metal.

Question 28

Why are metals good conductors of heat?

Answer 28

Because energy is transferred by delocalized electrons.