radioactivity

Question 1

what is the size of an atom?

Answer 1

around 0.1 - 0.5 nm

Question 2

what is the structure of an atom?

Answer 2

in the middle of the atom there is a nucleus, where there are protons and neutrons. around the nucleus there are electron shells, with electrons attached to them. In the first electron shell, there are 2 electrons. The other electrons can have up to 8 electrons

Question 3

what is the atomic charge of a proton?

Answer 3

+1

Question 4

what is the atomic charge of a neutron?

Answer 4

0

Question 5

what is the atomic charge of an electron?

Answer 5

-1

Question 6

what is the atomic number?

Answer 6

the number of protons in an atom

Question 7

what is the atomic mass?

Answer 7

the total number of protons and neutrons in an atom

Question 8

how can you figure out how many protons an atom has?

Answer 8

the number of protons is equal to its atomic number

Question 9

how can you know how many neutrons an atom has?

Answer 9

substract the mass number (proton + neutron) and the atomic number (proton)

Question 10

how can you know how many electrons are in an atom?

Answer 10

typically the number of electrons are the same amount as the number of protons

Question 11

what is an isotope?

Answer 11

atoms of the same element with the same number of protons but different number of neutrons
(same atomic number but different mass number)

Question 12

why do atoms have no overall charge?

Answer 12

because they contain an equal number of positively protons and number of negatively electrons

Question 13

why do ions have a charge?

Answer 13

because they have gained or lost electrons, therefore do not have an equal number of protons and electrons

Question 14

what is an ion?

Answer 14

an atom that has gained or lost one or more electrons, resulting in an electric charge

Question 15

will the absorption or emission of electromagnetic radiation make the position of electrons stay the same?

Answer 15

no, it will make the electron “excited”, jumping up an electron shell, however it will go back to its original shell once all the energy is lost

Question 16

what are the 3 main types of radiation?

Answer 16

1. Alpha rays
2. beta rays
3. gamma rays

Question 17

what is radioactive activity measured in?

Answer 17

Becquerels (Bq)

Question 18

what does a Geiger-Muller tube do?

Answer 18

detects and measures ionizing radiation

Question 19

why does a scientific model change over time?

Answer 19

because of the new data that gets collected, the technological advancements and improved understanding

Question 20

describe the plum pudding model

Answer 20

• early model of the atom, that depicted the atom as a sphere of positive charge with negatively charged electrons embedded within like plums in a pudding

Question 21

why did Rutherford’s experiment disprove the plum pudding model?

Answer 21

because the unexpected change of direction of alpha particles showed that an atom’s positive charge is not spread out like plums in a pudding, but instead concentrated in a small nucleus

Question 22

how did Bohr adapt the model of the atom?

Answer 22

he discovered electron shells

Question 23

what is B+ decay?

Answer 23

it is when an unstable nucleus with too many protons transforms one proton into a neutron and emits a positron to do so

Question 24

after B+ decay what stays the same (e.g does the mass number change?)

Answer 24

• the mass number stays the same
• the atomic number decreases by 1 because one proton to converted to a neutron

Question 25

what is B- decay?

Answer 25

it is a type of radioactive decay that occurs when a nucleus has too many neutrons, therefore transforms one neutron into a proton

Question 26

after B- decay what stays the same? (e.g does the mass number change?)

Answer 26

- the mass number stays the same -atomic number increases by 1, as there is now one more proton in the nucleus

Question 27

what does radioactive decay mean?

Answer 27

when an unstable atomic nucleus loses energy and transforms into a different, more stable nucleus by emitting radiation by random

Question 28

what does half-life mean?

Answer 28

the time for half of the unstable nucleus in a sample to decay

Question 29

what is nuclear fission?

Answer 29

when a nucleus of an atom splits into 2 small nuclei, releasing a lot of energy

Question 30

what is radioactive contamination?

Answer 30

the unintentional presence of radioactive material on surfaces, objects, or humans

Question 31

what precautions need to be taken around radioactive contamination? (3)

Answer 31

1. wear clothing that covers your face and skin overall 2. monitor the area often for contamination 3. keep as much distance between yourself and the source of radioactive contamination as possible

Question 32

what are the different sources of backround radiation?

Answer 32

- natural - e.g radioactive materials - artificial - e.g radiotherapy

Question 33

whats an alternative symbol to the Alpha decay rather than the symbol?

Answer 33

Helium

Question 34

what are the 2 ways that a beta particle can be represented?

Answer 34

- β - e

Question 35

when a neutrons decays into a proton, what happens?

Answer 35

it emits a high speed beta particle, which is an electrons moving very quickly, from the nucleus

Question 36

after beta-minus decay, what happens?

Answer 36

there will be one more proton and one fewer neutron in the nucleus. Because of this, the daughter nucleus is a different element to the parent nucleus

Question 37

whats a nucleon?

Answer 37

either a proton or a neutron, as they make up the nucleus

Question 38

when is Beta-minus decay most likely to occur?

Answer 38

in a nucleus with too many neutrons compared to protons. This leads to the daughter nucleus having one more proton than the parent, therefore is a different element

Question 39

describe beta-minus decay: (3)

Answer 39

- a neutron decays - a proton is produced which remains in the nucleus - an electron is produced which is ejected from the nucleus

Question 40

describe beta-plus decay: (3)

Answer 40

- a proton decays - a neutron is produced which remains in the nucleus - a positron is produced which is ejected from the nucleus

Question 41

after beta-plus decay, what happens in terms of neutrons and protons?

Answer 41

there will be one more neutron and one fewer proton in the nucleus, so the daughter nucleus is a different element to the parent nucleus

Question 42

summarise alpha decay:

Answer 42

an alpha particle forms and is ejected from the nucleus

Question 43

summarise Beta-minus decay:

Answer 43

a neutron converts to a proton and a beta particle is emitted

Question 44

summarise Beta-plus decay:

Answer 44

a proton converts to a neutron and a positron is emitted

Question 45

summarise Gamma emission:

Answer 45

excess energy is emitted from the nucleus as gamma radiation

Question 46

summarise Neutron emission:

Answer 46

a single neutron is ejected from the nucleus

Question 47

how do you find half-life from a decay curve?

Answer 47

divide the maximum counts per minute by 2, and from that number follow the line to the curve, and bring the line down to see how much it is in time