Atomic Structure

Question 1

What is radioactive decay

Answer 1

Some atomic nuclei are unstable. The nucleus gives out radiation as it changes to become more stable. This is a random process called radioactive decay. The other stable isotopes tend to decay into other elements and give up radiation as they try to become more stable. This is radioactive decay

Question 2

What is activity

Answer 2

the rate at which a source of unstable nuclei decays. (Bq)

Question 3

What is counter-rate

Answer 3

Count-rate is the number of decays recorded each second by a detector (eg Geiger-Muller tube).

Question 4

The nuclear radiation emitted may be:

Answer 4

Alpha
Beta
Gamma
Nuetron

Question 5

alpha particle (α)

Answer 5

this consists of two neutrons and two protons, it is the same as a helium nucleus.
Don’t penetrate very far into materials and are stopped quickly (few cm in air and are asorbed by a sheet of paper. Because of size thay are strongly ionising

Question 6

beta particle (β)

Answer 6

a high speed electron ejected from the nucleus as a neutron turns into a proton. It has vertualy no mass and a charge of -1. They are moderately ionising. They penetrate moderately into materials before colliding and have a range in air of a few meters. They are absorbed by a sheet of aluminium. For every beta particle emitted a nuetron in the nucleus has turned into a proton

Question 7

gamma ray (γ)

Answer 7

electromagnetic radiation from the nucleus. They penetrate far into materials meaning they are weakly ionising as they tend to pass through rather than collide with atoms. Absorb through thick sheets of lead or metres of concrete.

Question 8

What do radioactive substances spit out

Answer 8

One or more types of ionising radiation from there nucleus. They also release neutrons when they decay, as they rebalance their atomic and mass numbers.

Question 9

What is ionising radiation

Answer 9

Radiation that knocks electrons of atoms, creating positive ions, The ionising power of radiation source is how easily you can do this

Question 10

What are Nuclear equations

Answer 10

Nuclear equations are used to represent radioactive decay.

Question 11

In a nuclear equation an alpha particle may be represented by the symbol:

Answer 11

4
He
2
(Atomic number produces by two and its mass number reduces by four)

Question 12

In a nuclear equation an beta particle may be represented by the symbol:

Answer 12

0
e
-1
(Atomic number increases by one, doe snot cause the mass of the nucleus to change).

Question 13

What are nuclear equations

Answer 13

They are way of showing radioactive decay by using element symbols written in the form: Atom before decay = atom after decay + radiation emitted

Question 14

What is the rule of the nuclear equation

Answer 14

Put it on this and atomic numbers must be equal on both sides

Question 15

How do gamma rays affect the charge or mass of the nucleus

Answer 15

The emission of a gamma ray does not cause the mass or the charge of the nucleus to change.

Question 16

What process is radioactive decay

Answer 16

Radioactive decay is totally random. Radioactive substances give out radiation from the nuclear eye of the atoms no matter what. You can’t predict which nucleus in a sample with a K next or when any of them will decay

Question 17

The half-life of a radioactive isotope is …

Answer 17

the time it takes for the number of nuclei of the isotope in a sample to halve, or the time it takes for the count rate (or activity) from a sample containing the isotope to fall to half its initial level.

Question 18

How can you use Half life

Answer 18

You can find out the time it takes for the amount of radiation emitted by predictions about radioactive sources, even though the decays a random. All half life can be used to find the rate at which a source decays - it’s activity

Question 19

What happens to activity as a radioactive nucleus decays become a stable nucleus

Answer 19

As a whole the activity will decrease. Activity never reaches zero though which is why we have to use half-life to measure how quickly activity drips off

Question 20

Why would it be a short half life

Answer 20

If the nuclei is unstable and rapidly decays (find calcualtions in CGP

Question 21

How can you measure half life using a graph

Answer 21

You plot a graph of activity against time, it will always be shaped With the line going down. The half life is found from the graph by finding the time into full on the bottom axis corresponding the a halving of the activity on the vertical axis.

Question 22

What is Radioactive contamination

Answer 22

Radioactive contamination is the unwanted presence of materials containing radioactive atoms on other materials. The hazard from contamination is due to the decay of the contaminating atoms.

Question 23

What affects Radioactive contamination

Answer 23

The type of radiation emitted affects the level of hazard.

Question 24

What is irradatiom

Answer 24

Irradiation is the process of exposing an object to nuclear radiation. The irradiated object does not become radioactive.

Question 25

How do you reduce effects of irradation

Answer 25

Keeping sources in lead-lined boxes, standing behind barriers or bekng in a different room using a remote-controlled arm

Question 26

Ways to prevent contamination

Answer 26

Wearing gloves and using tongs. Some people wear protective suits to stop breathing in particles

Question 27

Out side the body contamination/irradation

Answer 27

Outside the body, beta and gamma sources are msot dangerous as they can penetrate the body and get to delicate oragns. High levels of irriadtions from all sources are dangerous.

Question 28

Inside the body contamination/irradation

Answer 28

Alpha sources are the most dangerous as they all do their damage in a very localised area. So contamination is the major concern. Beta sources are less damaging inside the body as radiation is absorbed over a wider area amd some passes out. Gamma has the lowest ionising point and pass straight out.