Chemistry Year 9 content

Question 1

what charge does a proton have

Answer 1

positive

Question 2

what mass does a proton have

Answer 2

1

Question 3

what charge does an electron have

Answer 3

negative

Question 4

what mass does an electron have

Answer 4

neglectable, almost zero

Question 5

what charge does a neutron have

Answer 5

0

Question 6

what mass does a neutron have

Answer 6

1

Question 7

define isotope

Answer 7

an atom from the same element with a different amount of neutrons but the same protons and electrons

Question 8

how to calculate RAM (relative atomic mass)

Answer 8

mass number x abundence / 100

Question 9

how are the particles arranged in a gas

Answer 9

-random
-far appart

Question 10

how are the particles arranged in a liquid

Answer 10

-random
-close together

Question 11

how are the particles arranged in a solid

Answer 11

-regular
-closely packed

Question 12

what is the movement of the particles in a gas

Answer 12

-fast in all directions

Question 13

what is the movement of the particles in a liquid

Answer 13

-move around each other

Question 14

what is the movement of the particles in a solid

Answer 14

-vibrate around fixed positions

Question 15

what is it called when you go from a gas to a liquid

Answer 15

condensing

Question 16

what is it called when you go from a gas to a solid

Answer 16

deposition

Question 17

what is it called when you go from a liquid to a gas

Answer 17

evaporation or boiling

Question 18

what is it called when you go from a liquid to a soldi

Answer 18

freezing

Question 19

what is it called when you go from a solid to a liquid

Answer 19

melting

Question 20

what is it called when you go from a solid to a gas

Answer 20

sublimation

Question 21

how are particles attracted to each other

Answer 21

by weak forces of attraction

Question 22

what does the heating curve look like

Answer 22

line steadily increasing until 0 degrees then going constant. after a few mins increasing again until going constant. after a shorter time it increases

Question 23

why on the heating curve does the line go constant at 0 degrees?

Answer 23

-the temperature stays constant while the solid is melting into a liquid. the substance is still being heated, but the added energy is making the particles break away from their fixed arrangement

Question 24

why on the heating curve does the line go constant for the second time

Answer 24

-the temperature stays constant while the liquid is boiling to a gas. the particles are escaping from the liquid to form a gas

Question 25

how can you predict the state of the substance by their temperature?

Answer 25

if it is: -below the melting point, the substance is solid -between the melting point and boiling point, the substance is liquid -above the boiling point, the substance is gas

Question 26

what do mixtures contain

Answer 26

-elements and/or compounds that are not chemically joined together -you can use physical processes to separate mixtures into different substances

Question 27

what do mixtures not have

Answer 27

a fixed composition

Question 28

what is filtrating

Answer 28

-can be used to separate some mixtures. -they let smaller pieces or liquids through but trap bigger pieces or insoluble substances

Question 29

what is crystallisation

Answer 29

solutes can be separated from a solution by evaporating the solvent to leave the solutes behind.

Question 30

what is a solution

Answer 30

a mixture made of solutes in a liquid

Question 31

what is a solute

Answer 31

dissolved substances

Question 32

what is simple distillation

Answer 32

used for separating out a liquid from a solution

Question 33

what is the practical of simple distillation

Answer 33

-pour your sample of seawater into the flask -set up the equipment. connect the bottom end of the condenser to a cold tap using rubber tubing. run cold water through it to keep it cool -gradually heat the flask over a Bunsen burner. the part of the solution that has the lowest boiling point will evaporate (water) -the water vapour passes into the condenser where it cools and condenses. it then flows into the beaker where it is collected. -eventually you'll end up with just the salt in the flask

Question 34

what are the problems with simple distillation

Answer 34

-you can only use it to separate things with very different boiling points

Question 35

what is fractional distillation

Answer 35

a mixture of liquids with similar boiling points you use fractional

Question 36

what is the practical of fractional distillation

Answer 36

-pour your mixture in a flask. Attach a fractioning column and condenser above the flask. -gradually heat the flask. the different liquids will all have different boiling points- so they will evaporate at different temperatures -the liquid with the lowest boiling point evaporated first. when the temperature on the thermometer matches the boiling point of this liquid, it will reach the top of the column -liquids with higher boiling points might also start to evaporate. but the column is cooler towards the top, so they will only get part way up before condensing and running back down towards the flask -when the first liquid has been collected, raise the temperature until the next one reaches the top

Question 37

what is chromatography

Answer 37

a method used to separate a mixture of soluble substances and identify them

Question 38

what are the two phases of chromatography

Answer 38

-a mobile phase -a stationary phase

Question 39

what is the mobile phase of chromatography

Answer 39

where the molecules can move. this is always a liquid or a gas

Question 40

what is the stationary phase of chromatography

Answer 40

where the molecules can't move. this can be a solid or a really thick liquid

Question 41

what is the method of the practical for chromatography

Answer 41

-draw a line near the bottom of the paper- this is the base line. do this with a pencil. put a spot of mixture to be separated on the line -put some of the solvent into a beaker. dip the bottom of the paper into the solvent -put a watch glass on the top of the beaker to stop any solvent from evaporating away -the solvent will start to move up the paper. when the chemicals in the mixture dissolve in the solvent, they will move up the paper too -you will see the different chemicals in the sample separate out, forming spots at different places on the paper -remove the paper from the beaker before the solvent reaches the top. mark the distance the solvent has moved in pencil

Question 42

what does the amount of time the molecules spend in each phase depend on in the chromatography practical.

Answer 42

-how soluble they are in the solvent -how attracted they are to the stationary phase

Question 43

what is known as surface water

Answer 43

water from lakes, rivers and reservoirs

Question 44

what is known as ground water

Answer 44

water from aquifers (rocks that trap water underground)

Question 45

what is known as waste water

Answer 45

water that has been contaminated by a human process

Question 46

what are the processes to purifying water

Answer 46

-filtration -sedimentation -chlorination

Question 47

what happens in filtration when purifying water

Answer 47

a wire mesh screens out large twigs and then gravel and sand beds filter out any other solid bits

Question 48

what happens in sedimentation when purifying water

Answer 48

iron sulfate or aluminium sulfate is added to the water, which makes fine particles clump together and settle at the bottom

Question 49

what happens in chlorination when purifying water

Answer 49

chlorine gas is bubbled through to kill harmful bacteria and other microbes