Matter P1

Question 1

what did Democritus say about atoms

Answer 1

although objects could be cut into smaller pieces, the smallest possible piece would be indivisible

Question 2

what was JJ Thompson’s plum pudding model

Answer 2

the atom had negatively charged electrons (the plums) in a positively charged (pudding)

Question 3

explain Rutherford’s alpha particle scattering experiment

Answer 3

he guided Geiger and Marsden to beam alpha particles at a thin gold foil and found that most of the alpha particles passed straight through but some of the alpha particles deflected from their path but continued and a few of the alpha particles bounced back off the gold foil

Question 4

what was Rutherford’s conclusion about why most alpha particles went straight through the gold foil

Answer 4

atoms are mostly empty space

Question 5

explain the nuclear model

Answer 5

all mass of atoms is concentrated in the positively charged nucleus and negatively charged electrons orbit the nucleus

Question 6

what was Bohr’s model of the atom

Answer 6

the electrons orbit in distinct energy levels, which are at different distances from the nucleus (2,8,8)

Question 7

why did Rutherford’s alpha scattering experiment lead to the nuclear model and replace the ‘plum pudding’ model

Answer 7

The experimental results of the gold foil experiment couldn’t be explained using the plum pudding model so it was disapproved and the nuclear model was devised to match the results

Question 8

why it is important that the experimental results and the predictions of the nuclear model is the same

Answer 8

if the predictions are correct then this proves that the nuclear model is correct

Question 9

explain the parts of the atom

Answer 9

the nucleus contains protons and neutrons and electrons orbiting the nucleus

Question 10

how small are atoms

Answer 10

1 × 10-10 m

Question 11

what are atoms

Answer 11

building blocks of all matter

Question 12

what is density

Answer 12

the mass per unit of a material

Question 13

equation for density

Answer 13

density = mass / volume

Question 14

why are gases less dense than solids

Answer 14

the molecules are more spread out

Question 15

if an object is more dense than water (1000kg/m^3) what will happen

Answer 15

the object sinks

Question 16

since solids and liquids are tightly packed what does it have

Answer 16

a high density

Question 17

why do gases have a lower density

Answer 17

because the molecules are widely spreaded

Question 18

what is the aim of the experiment of measuring the density of regular shaped objects

Answer 18

to determine the densities of regular objects by using measurements of their dimensions

Question 19

how do you calculate the volume of a cylinder

Answer 19

pie x r^2 x L

Question 20

state the apparatus needed to determine density

Answer 20

object, liquids, ruler, digital balance, eureka can, measuring cylinders

Question 21

what are the six changes of state that can occur between solids, liquids and gases

Answer 21

melting, evaporating, freezing, condensation, subliming, desubliming

Question 22

what is conversion of mass

Answer 22

when a substance changes state, the number of molecules doesn’t change so neither does its mass

Question 23

what are physical changes

Answer 23

reversible

Question 24

what are chemical changes

Answer 24

irreversible

Question 25

describe the molecules in a solid

Answer 25

very close together in a pattern and they vibrate about fixed positions

Question 26

describe the molecules in a liquid

Answer 26

close together but not in a pattern and they are able to slide past eachother

Question 27

describe the molecules in a gas

Answer 27

widely spread and move about randomly at high speeds

Question 28

define internal energy

Answer 28

total energy stored in a system by the particles that make up the system

Question 29

what are two types of energy

Answer 29

kinetic and potential energy

Question 30

how does heating a system change a substances internal energy

Answer 30

increases the kinetic energy of its particles so it moves faster

Question 31

what happens when a substance reaches a certain temperature

Answer 31

the kinetic energy of the molecules will stop increasing and the energy will go into increasing its potential energy instead

Question 32

define specific heat capacity

Answer 32

the amount of energy required to raise the temperature of 1 kg of the substance by 1 °C

Question 33

what happens if a substance has a low specific heat capacity

Answer 33

it heats up and cools down quickly because it takes less energy to change it's temperature

Question 34

define specific latent heat

Answer 34

the amount of thermal energy required to change the state of 1 kg of a substance with no change in temperature

Question 35

what are the 2 types of specific latent heat

Answer 35

specific latent heat of fusion and specific latent heat of vaporisation

Question 36

when is specific latent heat of fusion used

Answer 36

when melting a solid or freezing a liquid

Question 37

what is the difference between specific heat capacity and specific latent heat

Answer 37

specific heat capacity of water is the energy needed to increase the temperature of the water whereas specific latent heat of fusion is the energy needed to melt the ice with no temperature change

Question 38

equation for change in thermal energy

Answer 38

Mass × Specific heat capacity × Change in temperature

Question 39

equation for thermal energy required for a change of state

Answer 39

Mass × Specific latent heat Q = mL

Question 40

how do you convert cm^3 into m^3 to calculate volume

Answer 40

divide by 100^3

Question 41

describe the experiment used to calculate the density of an irregular solid object

Answer 41

-fill a eureka can with water -place a measuring cylinder under spout and put the object in the can, displaced water will come out the spout -measure the volume of water collected in the cylinder -repeat 3 time and calculate mean

Question 42

what is a closed system

Answer 42

no particles can escape and none can get in

Question 43

what does heating a substance do

Answer 43

increase the energy in it's thermal energy store

Question 44

what do energy stores do for a given change in temperature

Answer 44

gain lots of energy to warm up and release lots of energy when cooled down

Question 45

when heating a solid or liquid what happens

Answer 45

energy is transferred to the kinetic energy stores of the particles so they vibrate and move faster

Question 46

how does colliding gas particles create pressure

Answer 46

gas particles move randomly and bump into eachother and walls of container which exerts a force and pressure is created

Question 47

how does changing the temperature change the pressure

Answer 47

if there is a lot of heat more energy is transferred so gas particles move faster and more often so there is higher pressure but if the gas is cooled less energy is transferred so less force, often and quickly so lower pressure

Question 48

equation for constant temperature

Answer 48

pressure X volume = constant

Question 49

equation for pressure

Answer 49

pressure = force/area