P6.1 - Radioactive Emissions Flashcards Preview

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Flashcards in P6.1 - Radioactive Emissions Deck (36)
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1
Q

What is the mass of a proton?

A

1

2
Q

What is the mass of an electron?

A

1/2000

3
Q

what is the mass of a neutron?

A

1

4
Q

what is the relative charge of a neutron?

A

0

5
Q

what is the relative charge of an electron?

A

-1

6
Q

what is the relative charge of a proton?

A

+1

7
Q

What does the charge on the nucleus of an atom depend on?

A

The number of protons in it

8
Q

What are isotopes?

A

Atoms of an element with different numbers of neutrons

9
Q

what does the ‘12’ refer to in the atom:

carbon-12

A

the total number of subatomic particles in the nucleus

10
Q

how do you work out the number of neutrons in an atom?

A

subtract the amount of protons (or atomic number) from the relative atomic mass

11
Q

What do unstable nuclei emit?

A

Radiation

12
Q

What do you call materials that emit radiation?

A

radioactive

13
Q

What is the symbol for an alpha particle?

A

α

14
Q

what is the symbol of a beta particle

A

β

15
Q

what is the symbol for a gamma particle?

A

γ

16
Q

How is radiation detected?

A

Using a Geiger counter.

device clicks when radiation enters it

17
Q

what is each click in a Geiger-Miller tube?

A

a tiny current produced when radiation ionises atoms of gas inside the tube

18
Q

List three types of radiation in order from least penetrating to most penetrating.

A

alpha
beta
gamma

19
Q

What material stops alpha particles?

A

a few sheets of paper

20
Q

what material stops beta particles?

A

a few mm of aluminium

21
Q

what material stops gamma particles?

A

a few cm of lead (or m of concrete)

22
Q

what kind of radiation is emitted by radioactive materials?

and what does it mean?

A

ionising radiation,

means that the radiation can remove electrons from atoms or give electrons to atoms to produce ions

23
Q

what is the charge of alpha particles?

A

+2

24
Q

what is the charge of beta particles?

A

-1

25
Q

what is the charge of gamma particles?

A

0

26
Q

why do alpha particles have a shorter range than gamma particles?

A

because they have high ionising power (transfer more energy to the material that they are travelling through)

27
Q

What happens in alpha decay?

A

2 protons and 2 neutrons form an alpha particle and leave the nucleus

28
Q

Why does alpha decay occur?

A

since the atom that they are in have an unstable nuclei (too many protons)

29
Q

Finish off the equation: (alpha decay)

240
Pu —->
94

A

236 4
U + He
92 2

30
Q

What happens in beta decay?

A

When a neutron decays and emits an electron. The neutron itself turns into a proton.

31
Q

when does gamma ray decay occur?

A

when a nucleus usually emits an alpha particle or a beta particle (at the same time)

32
Q

what is a half-life of a radioactive material?

A

the time it takes for half the unstable nuclei to decay, or for the activity to halve

33
Q

What is the activity/count rate of a radioactive substance measured in?

A

Becquerels (Bq)

34
Q

Radioactive decay is random. Explain what that means

A

Random means that an event is equally likely in any time interval.

35
Q

Emission and absorption spectra tell us what about atoms?

A

Where the electrons are on the atom

36
Q

How many isotopes will be let after 4 weeks if the original sample had 100 atoms? Half-life of the isotope in question = 7 days

A

~6 (6.25)