atomic structure

Question 1

How does radioactivity occurr?

Answer 1

Through an unstable isotope’s nuclei decaying, a piece of matter or wave is emitted called radiation .

Question 2

name the 3 types of radiation

Answer 2

gamma, beta, alpha

Question 3

what does a geiger mullen tube count?

Answer 3

The amout of nuclei decaying in the air at any given time

Question 4

true or false you can find out which particle will decay next in a source?

Answer 4

False

Question 5

what is the activity of decaying measured in?

Answer 5

Becquerels (Bq)

Question 6

name the structure of an alpha particle

Answer 6

Made of two protons and two neutrons together
is positive
has high ionising potential to the human body

Question 7

why wouldn’t gamma radiation be used in an experiment with aluminum foil?

Answer 7

gamme requires thick concrete or lead to be stopped, high penetration rate

Question 8

All atoms of gold have the same number of ……………………………………………………….
and the same number of ………………………………………………………….. .
The atoms from different isotopes of gold have different numbers of …………………… .
A beta particle is an ………………………………………………………….. emitted
from the ………………………………………………………….. of an atom.
fill in the gaps

Answer 8

protons and neutrons

different isotopes have different numbers of electrons

beta particles is an electron immited from the
nucleus

Question 9

which is the least ionising
gamma
beta
alpha

Answer 9

gamma

Question 10

if a radiation is ionising what dangers can it cause?

Answer 10

Increased risk of mutations and tumors

Question 11

what is gamma

Answer 11

a radiation in the source of an electromagnetic wave (doesn’t have a nuclear equation)

Question 12

why is gamma so low ionising?

Answer 12

can pass through most electrons and materials

Question 13

Nuclear equation for alpha radiation

Answer 13

Is the same for a He atom

2He two protons and two neutrons
4

Question 14

nuclear equation for beta

Answer 14

0 e is an electron emmited from an
-1 unstable nucleus

Question 15

uranium 238U emmits an alpha
92
particle what will it become?

Answer 15

234Th = 238 U _ 4He
90 92 2

Question 16

39K emmits beta radiation. find it
19

Answer 16

39K = 39K - 0e
18 19 -1

Question 17

definition of a half life

Answer 17

the approx time it takes for all nuclei to decay the time is called the activity or the count rate

Question 18

The half-life of a radioactive isotope is 27 years. How long will its mass take to fall from 2 g to 0.25 g?

Answer 18

2 g → 1 g → 0.5 g → 0.25 g. Three arrows represent three half-lives. 3 × 27 years = 81 years

Question 19

Definition of nuclear fission

Answer 19

The splitting of large ,unstable nuclei to form more stable nuclei, and a few neutrons which carry lots of energy

Question 20

What provokes an unstable nucleus to split?

Answer 20

Nucleus has to absorb a slow moving neutron for fission to occur

Question 21

give an example of a fissionable isotope

Answer 21

Uranium -235

Question 22

Alongside the two stable nucleus what else is realsed in the fission reaction?

Answer 22

neutrons
gamma rays
energy

Question 23

what energy do all fission products contain?

Answer 23

kinetic energy

Question 24

describe the nuclear chain reaction

Answer 24

An unstable nucleus absorbs a neutron
the nuclei go through fission and releases 2 or 3 neutrons which induce further fission and create a chain reaction

Question 25

Consequences of an uncontrolled nuclear reaction?

Answer 25

the result of the fission will lead to too much uncontrolled energy and possibly a nuclear explosion

Question 26

structure of a beta particle?

Answer 26

zero neutrons and -1 electron

Question 27

Define what activity measures

Answer 27

the rate of which a nuclei decays

Question 28

how does beta change the charge of an atom?

Answer 28

since it is an electron it will change the charge of the atom to increase (positive), since it has no neutrons it will not chnage the atomic mass

Question 29

The half life measures?

Answer 29

How long it takes for a nuclei to decay to half it’s activity

Question 30

why are isotopes with long half-life’s harmful?

Answer 30

Remain radioactive for much longer times
Must be stored in specifc ways in order to prevent interaction with humans and the environment

Question 31

give four sources of background radiation

Answer 31

1. rocks
2. cosmic rays
3. radon gas
   4.nuclear accidents

Question 32

define contamination

Answer 32

the presence of unwanted radioactive nuclei occurs if an object has had a radioactive material introduced to it or on it IS THE HARMFUL ONE

Question 33

define irradiation

Answer 33

Exposing a material to radiation however the material is not radioactive. e.g. sterilizing medical equipment with gamma rays
Irradiation does not cause radioactivity

Question 34

Background radiation is measured in radiation doses, what is the unit for doses?

Answer 34

measured in sieverts
1000 millisieverts = 1 sieverts

Question 35

Why are certain types of radiation chosen for medical tracers?

Answer 35

Radiation with a short half life
high penetration
low ionizing