P1 - matter

Question 1

what was the ‘plum pudding model’?

Answer 1

a model of the atom where negative electrons were spread through the positive ‘pudding’ that made up most of the atom

Question 2

what did JJ Thomson do?

Answer 2

in 1897, he figured out that atoms weren’t solid spheres, his measurement proved the existence of electrons and he came up with the ‘plum pudding model’

Question 3

what did Ernest Rutherford do?

Answer 3

in 1909, along with Hans Geiger and Ernest Marsden, Rutherford conducted the gold foil experiment

Question 4

what did the gold foil experiment involve?

Answer 4

firing positively charged alpha particles at an extremely thin sheet of gold

Question 5

what was expected to be the result of the gold foil experiment?

Answer 5

from the plum pudding model, they expected the particles to pass straight through the gold sheet or only be slightly deflected

Question 6

what actually happened in the gold foil experiment?

Answer 6

although most of the particles did go straight through the sheet, some were deflected more than they had expected, and a few were deflected back the way they had come- which the plum pudding model couldn’t explain

Question 7

what can be concluded from a small number bouncing straight back at the detector?

Answer 7

the mass of an atom is mostly concentrated in the centre in a dense nucleus

Question 8

what can be concluded from some of the particles being deflected at large angles?

Answer 8

the centre mass is positively charged and repels the alpha particles when they pass nearby

Question 9

what can be concluded from most particles passing straight through the gold foil?

Answer 9

most of the atom is made of empty space

Question 10

what was the result of the gold foil experiment?

Answer 10

Rutherford came up with the theory of the nuclear atom to explain his new evidence

Question 11

what did the model of the nuclear atom show?

Answer 11

Rutherfords model of a nuclear atom showed that most of the mass of an atom is concentrated in tiny, positively charged nucleus at the centre, surrounded by a ‘cloud’ of negative electrons (with most of the atom being empty space)

Question 12

what made Rutherford’s atomic model impossible?

Answer 12

scientists realised that electrons in a ‘cloud’ around the nucleus of an atom would be attracted to the nucleus, which would cause the atom to collapse

Question 13

what did Niels Bohr propose to overcome the issue of the collapsing atom?

Answer 13

he proposed a model where the electrons are in shells; he suggested that electrons can only exist in these shells (or fixed orbits), and not anywhere in between and that each shell has a fixed energy

Question 14

what is the nuclear radius?

Answer 14

about 1x10^-15m

Question 15

what is the diameter of an atom?

Answer 15

around 1x10^-10m

Question 16

what is formed when atoms join together?

Answer 16

molecules

Question 17

what is the equation for density?

Answer 17

density = mass / volume

Question 18

what are the units for density?

Answer 18

kg/m^3

Question 19

how do you measure the density of irregular objects?

Answer 19

use a displacement can

Question 20

what are the rays given out by hot metals called?

Answer 20

cathode rays

Question 21

what fraction of the mass of a hydrogen particle are the particles in a cathode ray?

Answer 21

1/1000

Question 22

in the crushing can demo, why does the can get crushed?

Answer 22

• when the can is heated, the gas expands
• the gas that has expanded leaves the can and so few particles remain
• as the can is put in water, it is sealed and so the gas suddenly cools down
• the cool gas’ particles move slowly so exert little pressure on the inside of the can
• the inside of the can’s pressure is now very low in comparison to the air pressure, so the can is crushed

Question 23

what are the equations for Boyle’s Law?

Answer 23

P is proportional to 1/V
PV = constant
P1V1 = P2V2

Question 24

how does Boyle’s Law say pressure and volume are related?

Answer 24

pressure is inversely proportional to volume
pressure is directly proportional to the inverse of volume

Question 25

what are the units used for pressure?

Answer 25

Pascals (Pa)
or
N/m^2

Question 26

what is absolute zero?

Answer 26

when the particles stop moving/colliding, the coldest possible temperature

Question 27

how many degrees celsius and kelvin is absolute zero?

Answer 27

-273.14 degrees celsius
0K

Question 28

what’s the equation for pressure?

Answer 28

pressure = perpendicular force / area

Question 29

what does work done mean?

Answer 29

energy transferred

Question 30

what does a straight line on a graph show?

Answer 30

that the two variables are proportional

Question 31

what does a straight line through the origin on a graph show?

Answer 31

that the two variables are directly proportional

Question 32

what are gas’ three main properties?

Answer 32

1. temperature
2. pressure
3. volume

Question 33

what happened to it’s temperature when the gas is compressed?

Answer 33

it rose

Question 34

who discovered the neutron in the nucleus?

Answer 34

James Chadwick

Question 35

what happens to atoms in a chemical reaction?

Answer 35

they are rearranged

Question 36

what word can describe all of the atoms in a particular element?

Answer 36

identical

Question 37

what is specific heat capacity?

Answer 37

the specific heat capacity of a material is the quantity of energy needed to raise the temperature of 1kg of that substance by 1 degree celsius

Question 38

what is specific latent heat?

Answer 38

the energy needed to break intermolecular bonds and cause a change of state of 1kg of a material

Question 39

how do you calculate change in thermal energy?

Answer 39

mass x specific heat capacity x change in temperature

Question 40

how do you calculate thermal energy for a change in state?

Answer 40

mass x specific latent heat

Question 41

what is the equation for pressure dues to a column of liquid?

Answer 41

height of column x density of liquid x g