Chapter 3 - Chemistry

Question 1

What are the properties of a solid?

Answer 1

Each particle in a solid is touching it’s nearest neighbours and they remain in this fixed agreement. They cannot move around but they do vibrate constantly.

Question 2

What are the properties of a liquid?

Answer 2

The particles in a liquid are also very close together but they can move past each other. This results in a constant changing, random arrangement of particles.

Question 3

What are the properties of a gas?

Answer 3

The particles in a gas have much more space between them. They can move around at high speeds in any direction. The hotter the gas is, the faster the particles move.

Question 4

When does a solid turn into a liquid?

Answer 4

At it’s melting point.

Question 5

When does a liquid turn into a gas?

Answer 5

At it’s boiling point.

Question 6

What does a compound contain?

Answer 6

Two or more elements, which are chemically combined.

Question 7

What happens when non-metals react with metals?

Answer 7

The non-metals atoms gain electrons to achieve the stable electronic structure of a noble gas.

Question 8

How do elements react?

Answer 8

Elements react together to form compounds by gaining or losing electrons or by sharing electrons.

Question 9

What happens when the elements from group 7 and group 1 react?

Answer 9

As they react, atoms of group 1 elements can each lose one electron to gain the stable electronic structure of a noble gas. This electron could be given to a group 7 element.

Question 10

What are ionic compounds held by?

Answer 10

Strong forces of attraction between their oppositely charged ions. This is called ionic bonding.

Question 11

What happens when an ionic compound is dissolved in water?

Answer 11

The lattice is split up by the water molecules.

Question 12

Why do ionic compounds conduct electricity when molten or dissolved in water?

Answer 12

This is because their ions can then become mobile and then carry charge through the liquid.

Question 13

What is covalent bonding?

Answer 13

When non-metals react together and their atoms share pairs of electrons to form molecules.

Question 14

How are covalent bonds formed?

Answer 14

When atoms of non-metals share pairs of electrons with each other.

Question 15

What do substances containing covalent bonds consist of?

Answer 15

Simple molecules, but some have giant covalent structures

Question 16

What are polymers made up of?

Answer 16

Many small reactive molecules that bond to each other to form long chains.

Question 17

What do substances made up of simple molecules have?

Answer 17

Low melting points and boiling points.

Question 18

Why do substances made up of simple molecules have low melting and boiling points?

Answer 18

The forces between the simple molecules are now weak.

Question 19

What charge do simple molecules have?

Answer 19

They have no overall charge, so they cannot carry electrical charge. Therefore, substances with simple molecules are not conductors of energy.

Question 20

What are models used for?

Answer 20

To help understand bonding, but each model has it’s limitations in representing reality.

Question 21

What are giant covalent structures held together by?

Answer 21

Covalent bonds throughout the lattice.

Question 22

What are the properties of covalently-bonded structures?

Answer 22

These substances have very high boiling and melting points.

Question 23

What does graphite contain?

Answer 23

Giant layers of covalently bonded carbon atoms.

Question 24

Why can graphite conduct electricity and thermal energy?

Answer 24

This is because of the delocalised electrons that can move along it’s layers.

Question 25

What does carbon (also) exist as?

Answer 25

Fullerenes, which can form large cage-like structures and tubes.

Question 26

What is graphene?

Answer 26

Graphene is a single layer of graphite and so it is just one atom thick.

Question 27

How are the atoms in metals built up?

Answer 27

They are built up as layer on layer in a regular pattern and are closely packed together.

Question 28

What does a metal consist of?

Answer 28

A metal consists of positively charged metal ions surrounded by a “sea” of delocalised electrons.

Question 29

What are alloys?

Answer 29

An alloy is a mixture of two or more elements, at least one if them is a metal

Question 30

Why can metals be bent or shaped?

Answer 30

Because the layer of the atoms (or positively charged atoms) in a giant metallic structure can slide over each other

Question 31

Why are alloys harder than metals?

Answer 31

Because the regular layers in a pure metal are distorted by atoms of different sizes in an alloy

Question 32

What do delocalised electrons in metals enable?

Answer 32

Electricity and thermal energy to be transferred through a metal easily.