atoms and isotopes (topic 4)

Question 1

(6)

Answer 1

structure:
- alpha particle consists of a helium nucleus
- alpha particle consists of 2 protons and 2 neutrons
- a beta particle is an electron
- a beta particle comes from the nucleus

penetration:
- alpha particles are very poorly penetrating
- alpha particles can penetrate a few cm in air
- alpha particles are absorbed by skin
- alpha particles are absorbed by thin paper
- beta particles can penetrate several metres of air
- beta particles can pass through thin metal plate / foil
- beta particles can travel further than alpha particles in air
- beta particles can travel further than alpha particles in materials like metals

deflection:
- alpha particles and beta particles are deflected in opposite directions in
an electric field
- beta particles are deflected more than alpha particles
- alpha particles have a greater charge than beta particles but beta particles have much less mass or beta particles have a greater specific charge than alpha particles

Question 2

Answer 2

• smaller than
• radon loses an alpha particle

Question 3

what is the mass number the same as

Answer 3

number of protons and neutrons

Question 4

what is the atomic number

Answer 4

number of protons

Question 5

in an atom what two things are the same number

Answer 5

electrons and protons

Question 6

what type of radiation does a smoke detector emit

Answer 6

alpha

Question 7

Answer 7

electrons

Question 8

Question 9

an alpha particle does not have any

Answer 9

electrons

Question 10

Answer 10

are highly ionising

Question 11

(1)

Answer 11

neutron discovered

Question 12

Answer 12

1 and 0
very small and -1

Question 13

(3)

Answer 13

• has a nucleus which is positive charge
• negative charged electrons
• orbit nucleus

Question 14

Answer 14

90

Question 15

Answer 15

100
157

Question 16

Answer 16

y and z
same number of protons

Question 17

what part of an atom determines its element

Answer 17

proton

Question 18

(3)

Answer 18

• A: alpha particle passes straight through the empty space of the atom
• B: alpha particle deflected by the positive nucleus
• C: alpha particle heading straight for the nucleus is deflected backwards

Question 19

(6)

Answer 19

• alpha particle scattering experiment
• alpha particles directed at gold foil
• most alpha particles pass straight through
• (so) most of atom is empty space
• a few alpha particles deflected through large angles
• (so) mass is concentrated at centre of atom
• (and) nucleus is (positively) charged
• plum pudding model has mass spread throughout atom
• plum pudding model has charge spread throughout atom

Question 20

Answer 20

• alpha radiation is P because alpha particles are positively charged
• gamma radiation is Q because gamma rays are neutral
• (so beta particles are negatively charged)

Question 21

Answer 21

Question 22

Answer 22

to inject… tracer

Question 23

or (a neutral atom has no overall charge, explain this in terms of its particles) (2)

Answer 23

• equal numbers of protons and electrons
• protons and electrons have equal but opposite charge

Question 24

Answer 24

3 fewer neutrons

Question 25

an isotope has the

Answer 25

same number of protons but different numbers of neutrons

Question 26

Answer 26

neutron

Question 27

Answer 27

nuclear fission

Question 28

Answer 28

90 140

Question 29

(3)

Answer 29

- alpha (particle) - mass number goes down by 4 - number of protons and neutrons goes down by 4 - or number of neutrons goes down by 2 (emits alpha radiation because it undergoes alpha decay, the type of nuclear decay that ejects an alpha particle from the nucleus, ---------- unstable isotopes are unstable because their ratio of neutrons to protons causes an imbalance in the energies working to hold the nucleus together or push the nucleus apart)

Question 30

Answer 30

L J K

Question 31

Answer 31

cosmic rays from space

Question 32

Answer 32

- nuclear power - nuclear accidents

Question 33

Answer 33

- different number of / fewer protons - or different atomic number

Question 34

which is the atomic/proton number

Answer 34

top number

Question 35

which is the atomic mass number

Answer 35

bottom number

Question 36

Answer 36

168

Question 37

Answer 37

how many people in each group developed cancer

Question 38

describe the structure of the alpha particles used in this experiment

Answer 38

helium nuclei

Question 39

some positively charged alpha particles were deflected through large angles, explain what can be concluded from this observation

Answer 39

- deflections through large angles show the nucleus repels the alpha particle - nucleus must be positively charged as like charges repel - mass is concentrated at the centre of atom

Question 40

Question 41

an ion of magnesium has 12 protons in the nucleus and 10 electrons in orbital shells, calculate the relative charge on the ion

Answer 41

+2

Question 42

describe the structure of the atom in the plum pudding model (2)

Answer 42

- sphere of positive charge - negative charges dotted throughout the atom

Question 43

draw an isotope of the nucleus of lithium

Answer 43

- number of protons = 3 - different number of neutrons - expect to see 2,3,5, or 6 neutrons

Question 44

what is the charge of alpha particles

Answer 44

positive

Question 45

what is the charge of gamma radiation

Answer 45

neutral

Question 46

what is the charge of beta particles

Answer 46

negative