SC1-3

Question 1

what are particles in solids like

Answer 1

regular, close, vibrate in fixed positions and have strong attractive forces

Question 2

what are particles in liquids like

Answer 2

random, close, move around each other and have fairly strong attractive forces

Question 3

what are particles in gases like

Answer 3

random, far apart, fast moving in all directions and have weak attractive forces

Question 4

changes from:
solid –> liquid
solid –> gas

Answer 4

melting
sublimation

Question 5

changes from:
liquid –> gas
liquid –> solid

Answer 5

evaporation
freezing

Question 6

changes from:
gas –> liquid
gas –> solid

Answer 6

condensation
deposition

Question 7

what is a mixture

Answer 7

a material made of elements and/ or compounds not chemically joined together which can be seperated

Question 8

give an example of a mixture

Answer 8

air - made of oxygen and carbon dioxide
salt water - salt and water

Question 9

what is a pure substance

Answer 9

a substance that is the same in all parts, its composition cannot changed

Question 10

give an example of a pure substance

Answer 10

gold - it only contains gold atoms

Question 11

what happens at melting points

Answer 11

the substance gains enough energy to overcome their forces of attraction so the particles move further apart and the solid becomes a liquid

Question 12

mixtures do not have ___ melting points

Answer 12

fixed

Question 13

what can filtration do and how

Answer 13

separate a mixture by letting liquid or small substances through but not larger or insoluble substances

Question 14

what is a solution

Answer 14

a mixture of solutes in a solvent

Question 15

what does crystallisation do and how

Answer 15

separate a solution by evaporating the solvent out, leaving the solute

Question 16

what is a saturated solution

Answer 16

a solution with the maximum amount of solute dissolved in it

Question 17

what equipment is used for a simple filtration experiment

Answer 17

filter funnel, filter paper and a flask

Question 18

what equipment is used in a simple crystallisation experiment

Answer 18

bunsen burner, gauze, flask and evaporating basin

Question 19

what does chromotography do

Answer 19

find out which coloured compounds are in a mixture

Question 20

how do you calculate Rf value

Answer 20

distance moved by spot ÷ distance moved by solution

Question 21

what does distillation do and how

Answer 21

make water pure by separating it from dissolved solids

Question 22

what is desalination

Answer 22

produce of pure water from sea water

Question 23

what is chlorination

Answer 23

when chlorine is added to water to kill microorganisms

Question 24

what is sedimentation

Answer 24

letting small particles settle out

Question 25

what are the four steps to purify water

Answer 25

screening, sedimentation, filtration and chlorination

Question 26

what is all matter made of

Answer 26

tiny particles called atoms

Question 27

atoms cannot be ________

Answer 27

created or destroyed

Question 28

mass and charge of a proton

Answer 28

mass of 1 charge of +1

Question 29

mass and charge of a neutron

Answer 29

mass of 1 charge of 0

Question 30

mass and charge of an electron

Answer 30

mass of 1/1835 charge of -1

Question 31

do atoms have an overall charge and why

Answer 31

no - they have equal proton and neutron numbers

Question 32

where are electrons, protons and neutrons located

Answer 32

electrons - on shells outside the nucleus protons and neutrons - in the nucleus

Question 33

what are atomic numbers and mass numbers

Answer 33

atomic number - number of protons mass number - number of protons + neutrons

Question 34

what is are isotopes

Answer 34

two elements with the same atomic number but different mass number - different number of neutrons

Question 35

how can isotopes naturally be formed

Answer 35

radioactive nucleus decay