1) Radioactivity

Question 1

what did J.J. Thompson discover?

Answer 1

• electrons can be removed from an atom

- so an atom must have smaller parts

Question 2

what is the plum pudding model and who discovered it?

Answer 2

• Rutherford and Marsden

- firing alpha particles at thin gold foil and seeing how many went through

Question 3

what is the current model of the atom?

Answer 3

• positively charged nucleus

- negatively charged electrons

Question 4

what is the relative mass of a proton?

Answer 4

1

Question 5

what is the relative mass of a neutron?

Answer 5

1

Question 6

what is the relative mass of an electron?

Answer 6

0.0005

Question 7

what is the relative charge of a proton?

Answer 7

+1

Question 8

what is the relative charge of a neutron?

Answer 8

0

Question 9

what is the relative change of an electron?

Answer 9

-1

Question 10

what is the charge of the nucleus of each element and how if it different to isotopes?

Answer 10

• positive charge in the nucleus of each element

- isotopes differ in mass by having different numbers of neutrons

Question 11

in an atom the number of protons is equal…

Answer 11

to the number of electrons so atoms are neutral

Question 12

when are electrons able to change orbit?

Answer 12

when there is absorption or emission of electromagnetic radiation

Question 13

what happens if an atom looses an outer electon?

Answer 13

become positive ion

Question 14

how is beta minus, positron, gamma rays and neutron radiation emitted?

Answer 14

emitted from unstable nuclei in a random process

Question 15

what are better minus, positron and gamma rays?

Answer 15

ionising radiations

Question 16

what is meant by background radiation?

Answer 16

-low level radiation that surrounds us all the time

Question 17

where does background radiation come from?

Answer 17

• human activity, nuclear waste
• space
• naturally, air, foods, building materials

Question 18

how can we monitor radiation and stop irritation?

Answer 18

• medical people wear photographic film badges to monitor exposure
• keep things in lead boxes

Question 19

what is an alpha particle equivalent to?

Answer 19

helium nucleus

Question 20

what is a beta particle?

Answer 20

an electron emitted form the nucleus

Question 21

what is a gamma ray?

Answer 21

electromagnetic radiation

Question 22

how do alpha particles behave in terms of penetrations and ionising?

Answer 22

• dont penetrate far, quickly absorbed by materials

- strongly ionising because of size

Question 23

how do beta particles behave in terms of penetrations and ionising?

Answer 23

• moderately ionising
• beta- has a range of a few meters in air and abroad by aluminium
• beta+ have small range

Question 24

how do gamma particles behave in terms of penetrations and ionising?

Answer 24

• penetrate far into materials with being stopped

- weakly ionising

Question 25

what happens in the process of b- decay?

Answer 25

a neutron becomes a proton and an electron

Question 26

what happens in the process of B+ decay?

Answer 26

a proton becomes a neutron and a electron

Question 27

what happens to nuclei which has often undergone radioactive decay?

Answer 27

they undergo nuclear rearrangement with a loss of energy as gamma radiation

Question 28

how does the activity of a radioactive source decrease over time?

Answer 28

- as it decays a radioactive nucleus disappears - activity decreases - never reaches 0 - half life

Question 29

what is the unit of activity on a radioactive isotopes?

Answer 29

becquerel Bq

Question 30

what is the half life?

Answer 30

time taken for half the undecided nuclei to decay or the activity of a source to decay by a half

Question 31

can it be predicted when a particular nucleus decays?

Answer 31

- not be predicted | - half life enables large number of nuclei to be predicted

Question 32

HALF LIFE EQUATIONS

Answer 32

HALF LIFE EQUATIONS

Question 33

what are the dangers of ionising radiation?

Answer 33

- tissue damage | - mutations, cancer

Question 34

what is the safety done to protect people from radiation?

Answer 34

- medical, limiting doctors and patients by shielding | - limiting doses for patients as it kills too many cells

Question 35

what is contamination?

Answer 35

- radioactive partiales on objects | - may decay leasing radiation

Question 36

what are irradiation effects?

Answer 36

-exposure to radiation