Start of year recap test- Yr 9 topics

Question 1

What are all substances made of?

Answer 1

Atoms

Question 2

What is an atom?

Answer 2

The smallest part of an element that can exist

Question 3

What are atoms of each element represented by?

Answer 3

A chemical symbol

Question 4

What is an element?

Answer 4

A substance with only one kind of atom

Question 5

Where are elements listed?

Answer 5

The periodic table

Question 6

How many elements are there in the periodic table?

Answer 6

118

Question 7

What can elements be classified as?

Answer 7

Metals or non-metals depending on their properties

Question 8

What are the columns in the periodic table called?

Answer 8

Groups
They contain similar elements

Question 9

What are the rows in the periodic table called?

Answer 9

Periods
Element show a gradual change in properties across a period.

Question 10

How are compounds formed?

Answer 10

When some elements combine through chemical reactions

Question 11

What are compounds made from?

Answer 11

Two or more element combined together in fixed proportions.

Question 12

How can compounds be represented?

Answer 12

Using the symbols of the atoms they were made from e.g. CO2

Question 13

What does a mixture consist of?

Answer 13

Two or more elements or compounds not chemically combined together

Question 14

What happens to the chemical properties of the elements in a mixture?

Answer 14

Are unchanged

Question 15

Do compounds have different properties to they were made from?

Answer 15

Yes

Question 16

How can compounds be separated into elements?

Answer 16

By chemical reactions

Question 17

What are the physical processes by which mixtures can be separated?

Answer 17

Filtration, crystallisation, simple distillation,
fractional distillation and chromatography. These physical processes do not involve chemical
reactions.

Question 18

What type of mixture does simple distillation separate?

Answer 18

Soluble solids

Question 19

How does simple distillation work?

Answer 19

Liquid boils off and condenses in the condenser.
The thermometer will read the boiling point of the pure liquid.

Question 20

What type of mixture does crystallisation/evaporation separate?

Answer 20

A soluble solid and a liquid e.g. salt and water.

Question 21

What type of liquid must the soluble solid not be dissolved in to use evaporation?

Answer 21

Non-flammable

Question 22

What should we do if we want to create hydrated salt crystals using evaporation?

Answer 22

Don’t evaporate all the water from the mixture

Question 23

Why is the evaporating basin used in evaporation wide and shallow?

Answer 23

Gives the liquid a wider surface area for quicker evaporation.

Question 24

What type of mixture does fractional distillation separate?

Answer 24

Soluble liquids with different boiling points e.g. crude oil

Question 25

Does the fractionating column used in fractional distillation have a temperature gradient?

Answer 25

Yes- It’s hotter at the bottom than it is at the top

Question 26

How does fractional distillation work?

Answer 26

. Mixture of soluble liquids heated
. All liquids are evaporated
. Liquid with lower boiling point forms greatest % of vapour
. As vapour moves up the fractional column,
it becomes more rich with component with the lowest boiling point (due to vapour mixture condensing and evaporating as it moves up the column)
. Thermometer measures temps of the ‘fractions’ before they condense
. Liquid with lowest boiling point will be the first ‘fraction’ to collect
.

Question 27

What did the discovery of the electron lead to?

Answer 27

The plum pudding model

Question 28

What did the plum pudding model suggest about atoms?

Answer 28

That the atom was a ball of positive charge with negative electrons embedded in it