Y8 Chemistry revision

• Chemistry
• Lower Secondary (Key Stage 3)

	Solid	Liquid	Gas
Arrangement
Closeness
Movement
Can it flow?
Can it be compressed?

Use the answers to fill in the table.

Ordered

Close together

Close together

Random

Random

Fast

Yes

Yes

Yes

No

No

No

Far apart

Vibrating

Slow

What do you notice about the atoms making up these substances? 

Elements

Not elements

Nitrogen is an element.

1. True
2. False

Helium is an element.

1. True
2. False

Water is an element.

1. True
2. False

Lead is an element.

1. True
2. False

Air is an element.

1. True
2. False

Steel is an element.

1. True
2. False

Krypton is an element.

1. True
2. False

Gold is an element.

1. True
2. False

Unobtainium is an element.

1. True
2. False

Are these substances elements or not?

Elements

Not Elements

Silver

Oxygen

Water

Wood

Helium

How can you tell carbon dioxide is NOT an element?

Atom: the smallest part of an element to exist.

How many atoms can you see?

1. 1
2. 2
3. 3
4. 4

How many atoms can you see?

1. 1
2. 2
3. 4
4. 8

How many atoms can you see?

1. 2
2. 3
3. 5
4. 9

Molecule: 2 or more atoms strongly joined together.

Compound: atoms of 2 or more elements strongly joined together.

Element or compound?

Lead oxide

1. Element
2. Compound

Element or compound?

Nitrogen

1. Element
2. Compound

Element or compound?

Chlorine

1. Element
2. Compound

Element or compound?

Sodium Chloride

1. Element
2. Compound

Element or compound?

1. Element
2. Compound

Element or compound?

1. Element
2. Compound

Element or compound?

1. Element
2. Compound

How many elements can you see?

1. 2
2. 4
3. 7
4. 13

How many atoms can you see?

1. 2
2. 3
3. 7
4. 13

How many molecules can you see?

1. 2
2. 4
3. 7
4. 13

How many compounds can you see?

1. 2
2. 4
3. 7
4. 13

Why is O2 a molecule, but not a compound?

Match the word to the definition.

The smallest part of an element to exist.

2 or more atoms strongly joined together.

A substance made from one type of atom. 

Atoms of 2 or more elements strongly joined together.

Compound

Atom

Molecule

Element

How many oxygen atoms are there in each of these substances?

Substance	Oxygen Atoms
O
HNO
C H O
MgO
CO
MgCO

2

2

3

3

6

12

6

1

2

2

3

3

6

In a balanced equation the number of atoms of each element is the same on each side of the arrow.

Is this equation balanced?

1. Yes
2. No

Is this equation balanced?

1. Yes
2. No

Is this equation balanced?

1. Yes
2. No

Is this equation balanced?

1. Yes
2. No

To balance an equation we can multiply any of the existing substances until the number of atoms is equal.

Add one molecule to balance the  equation.

Add one molecule to balance the  equation.

Add two molecules to balance the equation.

Add two molecules to balance the  equation.

Add three molecules to balance the  equation.

Add two molecules to balance the  equation.