Atomic Physics Flashcards

To revise Atomic physics (paper 1)

You may prefer our related Brainscape-certified flashcards:
1
Q

State the typical size of an atom

A

1 x 10 -10 m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Describe the structure of an atom

A

A positively charge nucleus containing protons and neutrons surrounded by negatively charged electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

State the size of a nucleus compared to an atom

A

The radius of the nucleus is less than 1/10000 of the radius of an atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How can electrons move to a higher energy shell/level

A

By absorbing electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How can electrons move to a lower energy shell/level

A

By releasing electromagnetic radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the charge on an atom why?

A

Atoms are neutral as the number of positive protons is equal to the number of negative electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is an Ion?

A

A charged atom that has gained or lost electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The same element must always have the same number of…?

A

Protons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define the atomic number

A

Number of protons = number of electrons for an atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define nucleon number

A

mass mummer = Number of protons + number of neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define an isotope

A

The same element with the same number of protons but with a different number of neutrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Describe how the model of the atom has changed with new experimental evidence

A

Atoms were originally though to be tiny spheres that couldn’t be divided.
The discovery of the electron led to the plum pudding model of the atom.
The alpha particle scattering experiment led to the nuclear model of the atom - a positive nucleus which contained the majority of the mass.
Niels Bohr suggested that electrons orbited the nucleus in shells
James Chadwich discovered the neutron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the plum pudding model of the atom

A

A positive sphere with negative electrons dotted throughout it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the alpha particle experiment.

A

Alpha Partikels were fired at thin gold in a vacuum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe and explain the observations from the alpha particle experiment.

A

The majority of alpha particles went straight though the gold. so atoms are mainly empty space.
Some alpha particles were defected by the gold foil. there must be something positive which contained the majority of the mass in an atom (the nucleus)
A tiny fraction of alpha particles bounced back where they came from. the nucleus must be a tiny part of the atom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How can an unstable nucleus become more stable?

A

By giving out radiation (alpha, beta or gamma)

17
Q

Define activity

A

The rate at which a source of unstable nuclei decays

18
Q

State the units of activity

A

Becquerel (Bq)

19
Q

Define count rate

A

The number of decays recorded by a detector (GM tube)

20
Q

Describe a alpha particle

A

Two protons and two neutrons together. A helium nucleus

21
Q

Describe a beta partice

A

A fast moving electron ejected from the nucleus. This happens after a neutron has decayed into a proton

22
Q

Describe a gamma ray

A

An electromagnetic wave with no charge or mass.

23
Q

State the penetrating power of alpha, beta and gamma radiation.

A

Penetrating power is what can stop the radiation.
Alpha - skin, paper 5 - 10 cm of air
Beta - mm’s of aluminium, 1 meter of air
Gamma - reduced by cm’s of lead or m’s of concrete

24
Q

State the ionising ability of alpha, beta and gamma radiation.

A

Ionising ability is the ability to do damage to our living cells and tissues.
Alpha - highly ionising
Beta - moderately ionising
Gamma - very weakly ionising

25
Q

In decay equations what is the mass number and proton number for an alpha particle?

A

mass number = 4

proton number = 2

26
Q

In decay equations what is the mass number and proton number for a beta particle?

A

mass number = 0

proton number = -1

27
Q

In decay equations what is the mass number and proton number for a gamma wave?

A

mass number = 0

proton number = 0

28
Q

how can the rate of radioactive decay be increased?

A

It can be affected by physics quantities such as temperature or pressure. it is completely random.

29
Q

Define half life

A

The time taken for the number of radioactive nuclei in a sample to half.

30
Q

Define contamination

A

Unwanted presence of radioactive atoms on other materials such as clothes, buildings etc

31
Q

Define irradiation

A

The process of exposing an object to radiation. the object does become radioactive. e.g. killing bacterial on fruit to increase its shelf life.

32
Q

How should radioactive sources be used safely?

A

Use only for a short period of time.
Keep source at arms length
Point source away from yourself
Stored in a lead lined box with a radioactive symbol

33
Q

What is background radiation?

A

Radiation that is around us all the time

34
Q

State some sources of natural background radiation?

A

Rocks, cosmic rays, food

35
Q

State some sources of man made background radiation

A

X-rays, nuclear bombs, nuclear power stations