7H - Atoms, molecules, elements and compounds

Question 1

What is a molecule?

Answer 1

More than one atom bonded together.

Question 2

What are mixtures?

Answer 2

Materials that contain more than one substance which are NOT joined together.

Question 3

What happens if a natural material is pure?

Answer 3

Contains only one substance (isn’t mixed).

Question 4

What are elements?

Answer 4

Substances made out of only one type of atom.

Question 5

What are compounds?

Answer 5

Substances made out of more than one kind of atom (element) bonded together.

Question 6

What is O?

Answer 6

Oxygen

Question 7

What is Mg?

Answer 7

Magnesium

Question 8

What is Fe?

Answer 8

Iron

Question 9

What is Si?

Answer 9

Silicon

Question 10

Where do we obtain all the elemnts and compounds we need from?

Answer 10

From the earth’s atmosphere and crust.

Question 11

Why is it important to recycle?

Answer 11

Because our resources are limited and some may run out in the near future.

Question 12

What are the 5 common properties of metals?

Answer 12

• High melting point
• Strong and flexible
• Shiny
• Good conductors of heat
• Good conductors of electricity

Question 13

What are the 5 common properties of non metals?

Answer 13

• Low melting points
• Brittle
• Not shiny
• Poor conductors of heat
• Poor conductors of electricity

Question 14

What determines the uses of a material?

Answer 14

Its properties.

i.e. copper is strong, flexible and conducts electricity so its used for electricity cables.

Question 15

What is the name of the only liquid metal?

Answer 15

Mercury

Question 16

What is the first name of a compound if there’s a metal present?

Answer 16

The name of the metal

Question 17

What is the second name of a compound with only two elements?

Answer 17

one element name has its name ending changed to -ide

(i.e. sodium + chlorine = sodium chloride)

Question 18

If a compound contains two elements plus oxygen, what is its second name?

Answer 18

The name of an element with its ending changed to -ate.

(i.e. magnesium + nitrogen + oxygen = magnesium nitrate)

Question 19

What do chemical reactions always form?

Answer 19

New substances

Question 20

What are the typical signs of a chemical reaction taking place?

Answer 20

• Colour change
• Gas given off
• Solid being formed
• An energy change

Question 21

If a chemical reaction doesn’t need heat to continue reacting, does it need heat to start reacting?

Answer 21

Some reactions need heat to start, but once started they give off heat.

(i.e. burning petrol)

Question 22

Do all reactions need heat to start?

Answer 22

No. some just start reacting by getting mixed.

(i.e. acids and alkalis)

Question 23

Name a reaction that needs a continuous supply of energy (heat) to keep on going.

Answer 23

Breaking down metal ores

Question 24

Give examples of chemical reactions

Answer 24

Burning, cooking, rusting, digesting food.

Question 25

What happens during thermal decomposition reactions?

Answer 25

A single compound is broken down using heat. (i.e. Tin carbonate \> tin oxide + carbon dioxide)

Question 26

What is the word equation for the thermal decomposition of copper carbonate?

Answer 26

Copper carbonate \> copper oxide + carbon dioxide

Question 27

What is the main use of thermal decomposition reactions?

Answer 27

used in industry to extract metals from metal ores.

Question 28

What is the percentage of nitrogen in air?

Answer 28

78%

Question 29

What is the percentage of oxygen in air?

Answer 29

21%

Question 30

What is the percentage of 'other' gases that aren't oxygen or nitrogen in air?

Answer 30

1%