Particles and Radiation

Question 1

what is a particle?

Answer 1

a minute portion of matter

Question 2

what are atoms made up of?

Answer 2

protons, neutrons and electrons

Question 3

what is the charge of a proton?

Answer 3

+1

Question 4

what is the charge of a neutron?

Answer 4

0

Question 5

what is the charge of an electron?

Answer 5

-1

Question 6

what is the proton number?

Answer 6

the number of protons in the nucleus

Question 7

what is the proton number also called?

Answer 7

the atomic number

Question 8

will two elements ever have the same amount of protons?

Answer 8

no, because it is the proton number that defines the element

Question 9

how many electrons does a neutral atom have?

Answer 9

the same amount as it does have protons

Question 10

what is the total number of protons and neutrons called?

Answer 10

the nucleon number

Question 11

what is the nucleon number also referred to as?

Answer 11

the mass number

Question 12

what is something called if it has the same amount of protons but a different number of neutrons?

Answer 12

an isotope

Question 13

changing the number of neutrons…

Answer 13

…doesn’t affect the atom’s chemical properties

Question 14

what do the number of neutrons affect?

Answer 14

the stability of the nucleus

Question 15

in general, the greater number of neutrons compared with the protons,…

Answer 15

…the more unstable the nucleus is

Question 16

unstable nuclei may be radioactive…

Answer 16

…and decay to make themselves stable

Question 17

what is the relative mass of a proton?

Answer 17

1

Question 18

what is the relative mass of an electron?

Answer 18

0.0005

Question 19

what is the relative mass of a neutron?

Answer 19

1

Question 20

define proton number

Answer 20

no. of protons in the nucleus

Question 21

define nucleon number

Answer 21

total no. of protons & neutrons in the nucleus

Question 22

what does the strong nuclear force do?

Answer 22

binds nucleons together

Question 23

to hold the nucleus together, the strong nuclear force…

Answer 23

is an attractive force that is stronger than the electrostatic force

Question 24

what is the range of the strong nuclear force?

Answer 24

very short

Question 25

the strong nuclear force can only hold nucleons together if…

Answer 25

they are only a few femtometres apart

Question 26

what happens to the strength of the strong nuclear force at about 3 femtometres?

Answer 26

it falls rapidly towards zero

Question 27

the size of the strong nuclear force varies with…

Answer 27

…nucleon separation

Question 28

the electrostatic repulsive force extends over a much…

Answer 28

…larger range (indefinately)

Question 29

when is the strong nuclear force repulsive?

Answer 29

when it has nucleons of less than 0.5 femtometres

Question 30

when does alpha emission happen?

Answer 30

in very BIG atoms (with more than 82 protons)

Question 31

why are these atoms unstable?

Answer 31

because the nuclei in the atoms are too BIG for strong nuclear force

Question 32

what happens when an alpha particle is emitted?

Answer 32

the proton number decrease by 2 and the nucleon number decreases by 4

Question 33

where does beta emission happen?

Answer 33

in neutron-rich nuclei (isotopes)

Question 34

what is beta emission?

Answer 34

the emission of an electron from the nucleus as well as an antineutrino

Question 35

what happens to one of the neutrons in beta emission?

Answer 35

it changes into a proton

Question 36

what happens when a beta particle is emitted?

Answer 36

the proton number increases by 1 and the nucleon number stays the same

Question 37

what does an antineutrino carry?

Answer 37

energy and momentum

Question 38

what tiny neutral particle is emitted in beta decay?

Answer 38

an antineutrino

Question 39

what evidence suggests the existence of the strong nuclear force?

Answer 39

the electrostatic force is much larger than the gravitational force so in order to hold the nucleus together there must be another force: the strong nuclear force

Question 40

why must the strong nuclear force be repulsive at short distances?

Answer 40

because otherwise there would be nothing stopping it crushing a nucleus to point

Question 41

how does the strong interaction limit the size of a stable nucleus?

Answer 41

after very short space of time the strong nuclear force is larger than electrostatic and protons in nucleus are forced apart. (nucleus much bigger than this = unstable)