Atomic Structure

Question 1

Hos do isotopes give of radiation?

Answer 1

If they are unstable, they will decay into other elements and give of radiation as they decay. Neutrons can also be projected by the decaying isotope.

Question 2

What are the three types of radiation?

Answer 2

• Alpha (α)
• Beta (β)
• Gamma (γ)

Question 3

What is alpha radiation?

Answer 3

It is a helium nucleus (2 protons and 2 neutrons)

Question 4

What are the properties of alpha radiation?

Answer 4

• Very ionising
• Travel a few centimetres (short distances)
• Stopped by skin/smoke/paper

Question 5

What is beta radiation?

Answer 5

A fast moving electron, they are projected from the nucleus of the isotope. One neutron turns into a proton and an electron, the electron is shot out of the atom and the atom change to become another element as its proton number went up by one.

Question 6

What are the properties of beta radiation?

Answer 6

• Moderately ionising
• Travels a few metres (moderate distance)
• Stopped by an aluminium sheet

Question 7

What is gamma radiation?

Answer 7

Waves of electromagnetic radiation released from the nucleus.

Question 8

What are the properties of gamma radiation?

Answer 8

• Not very ionising
• Travels pretty much forever
• Stopped by lead or metres of concrete

Question 9

What always has to be true in a nuclear equation?

Answer 9

The mass number and atomic number on both sides have to total to equal the same.

Question 10

What happens to an isotope when it decays using alpha radiation?

Answer 10

It changes to an isotope with a proton number 2 less and loses 4 atomic mass (2 protons and 2 neutrons finna dip)

Question 11

What happens to an isotope when it decays using beta radiation?

Answer 11

Its mass number stays the same but its nucleus goes up by one charge as the isotope gains a proton, this changes the atoms to one above the original. e.g. Carbon 14 → Nitrogen 14 + e-
An electron is also blasted of.

Question 12

What happens to an isotope when it decays using gamma radiation?

Answer 12

Nothing, the isotopes just releases excess energy from its nucleus. The atomic number and mass number don’t change.

Question 13

Is radioactivity a structured process?

Answer 13

No, it is completely random when it takes place.

Question 14

What is half life?

Answer 14

The time taken for the number of radioactive nuclei in an isotope to half.

Question 15

How does the radioactivity of a source change over time?

Answer 15

A source of radiation becomes less radioactive over time because there are less particles to emit radiation. This means there is less chance for the substance to give off radiation since decay is random.

Question 16

What happens to a nucleus after each decay?

Answer 16

It becomes more stable

Question 17

Why do we use half life to measure radioactivity?

Answer 17

Because the radioactivity of a substance never reaches zero, so we can predict how long it takes to finish decaying using half lives.

Question 18

What is a short half life?

Answer 18

When the activity falls quickly because the nuclei are very unstable and rapidly decaying.

Question 19

Why are short half life emitters dangerous?

Answer 19

They emit a high amount of radiation at once, radiation can damage internal organs and kill you. However, they also become stable very quickly as they finish decaying quickly.

Question 20

What is a long half life?

Answer 20

When the activity falls quickly because the nuclei decay over a very ling period of time.

Question 21

Why can long half life be dangerous?

Answer 21

Areas around the radioactive substance are exposed to radiation over millions of years. Exposure to radiation over a long time can cause cancer.

Question 22

What is background radiation?

Answer 22

Sources of low level radiation that is around us all the time.

Question 23

What are some sources of background radiation?

Answer 23

> Natural unstable isotopes - in air, food and building materials
Radiation form space/ cosmic rays - they mostly come from the sun, the earth protects us form most of this radiation though
Human activity - nuclear testing, but this is a tiny proportion of the background radiation.

Question 24

What is it called when something is exposed to radiation?

Answer 24

The object is irradiated, we are always be irradiated from background radiation.

Question 25

What are ways to reduce irradiation?

Answer 25

- Keep sources of radiation in lead boxes - stand behind barriers or be in a different room - use remote controlled arms when handling radioactive sources.

Question 26

What is contamination?

Answer 26

When unwanted radioactive atoms get onto/into an object. The atoms may start to decay and release harmful radiation onto this object.

Question 27

What is the most harmful radiation from a source outside the body?

Answer 27

Beta and Gamma because it can penetrate skin and damage your organs. So irradiation is dangerous from gamma and beta radiation.

Question 28

What is the most harmful radiation from a source inside the body?

Answer 28

Alpha radiation because it is very ionising as ling as it finds a way into your boy, it is very harmful. So contamination is dangerous from alpha radiation.

Question 29

What are the risks of radiation?

Answer 29

- They can ionise the atoms in your cells and cause tissue damage, - Lower doses of radiation damage cells but don't kill them, these cells reproduce rapidly and are mutant cells. This creates a tumour (cancer), - If high doses of radiation are exposed to you, your cells will just die and you will feel very ill (radiation sickness).

Question 30

What are medical tracers?

Answer 30

Radioactive isotopes are injected into the patients body to makes sure it is functioning as it is, this can be checked by a detector picking up the gamma radiation from the isotope and making sure the body is working properly.

Question 31

What is radiotherapy?

Answer 31

``` If gamma rays are directed properly into cancer cells, the ionising strength of multiple gamma rays can kill the cancer cells (by focusing the rays) without killing any healthy cells. Radiation emitters (usually beta) can also be implanted next to tumours to kill the cancer. ```

Question 32

What is nuclear fission?

Answer 32

A nuclear reaction that realises a lot of energy by splitting unstable nuclei by propelling a neutron into the nuclei.

Question 33

How is nuclear fission used in a power plant to create electricity?

Answer 33

In a power plant, fission often causes chain reactions as 2 or 3 neutrons are released that collide with other nuclei. This energy can be used to heat water in a power plant and turn a turbine connected to a generator for electricity. The amount of energy produced can be controlled using control rods which are lowered and raised to absorb neutrons instead of allowing all the neutrons to cause a massive chain reaction.

Question 34

How do nuclear weapons use fission?

Answer 34

They are an uncontrolled, massive chain reaction of lots of unstable nuclei undergoing fission.

Question 35

What is nuclear fusion?

Answer 35

When two smaller nuclei collide at high speed at fuse into one nuclei. e.g. 2 hydrogen nucleus collide to form one helium nucleus. Some mass is lost as energy/ radiation.

Question 36

Which releases more energy: fusion or fission?

Answer 36

Fusion

Question 37

Why isn't fusion used in power plants for electricity?

Answer 37

The power plants are very expensive because the temperature and pressure has to be very high for fusion to happen.