Section 7: Radioactive Particles

Question 1

Understand the terms atomic (proton) number, mass (nucleon) number and isotope

Answer 1

atomic mass: the number of protons+ the number of neutrons.
atomic number: the number of protons. This will equal the number of electrons in an element.
Isotope: is an atomwith the same configuration of protons and electrons but a different amount of neutrons.

Question 2

Understand that alpha and beta particles and gamma rays are ionizing radiations emitted from unstable nuclei in a random process

Answer 2

alpha particles, beta particles and gamma rays are all types of radiation.
The term ionising means they damage cells.
Radiation is emitted from the nucleus of an atom that is unstable

Question 3

Describe the nature of alpha and beta particles and gamma rays and recall that they may be distinguished in terms of penetrating power

Answer 3

alpha particles are two neutrons and two protons; also known as a helium nucleus. Alpha particles could notpenetratea piece of paper if they tried.
Beta particles are electrons, they are emitted when a neutron turns into a proton and an electron. It won’tpenetrate aluminium.
Gamma rays are a type of electromagnetic wave, they are often emitted alongside the other types of radiation. Gamma cannot penetrate lead.

Question 4

Understand how to complete balanced nuclear equations

Answer 4

Nuclear equations show the atoms atomic number and atomic mass on one side and the radiation (with mass and number) and the new element (with mass and number.)

Question 5

Describe the dangers of ionising radiations:

Answer 5

radiation can cause mutations in living organisms
radiation can damage cells and tissue
the problems arising in the disposal of radioactive waste and describe how the associated risks can be reduced.

Question 6

Describe the results of Geiger and Marsden’s experiments with gold foil and alpha particles

Answer 6

Alpha radiation was beamed at a sheet of gold foil
a few went straight through
many were deflected at angles
some were deflected straight back.

Question 7

Describe the uses of radioactivity in medical and non-medical tracers, in radiotherapy, and in the radioactive dating of archaeological specimens and rocks

Answer 7

Tracers: aradioactivesource is put into a system (like a piping network), it will build up where there is a blockage a be detected, showing where a problem is. This can be used in the human circulatory system
Radiotherapy: radiation is used to destroy unwanted cells (cancerous cells.)
Carbon dating: The amount of radiation from an object is measured, the half life of the carbon is then used to see how old the object is

Question 8

Understand that a nucleus of U-235 can be split

Answer 8

This is called the process of nuclear fission. It evolves firing a neutron into the nucleus of a radioactive particle causing it to split releasing a few neutrons

Question 9

Understand that the fission of U-235 produces two daughter nuclei and a small number of neutrons

Answer 9

Uranium fission produces Krypton and Barium and 3 neutrons

Question 10

Understand that a chain reaction can be set up if the neutrons produced by one fission strike other U-235 nuclei

Answer 10

Because neutrons are released during the splitting of an atom, these neutrons can cause another splitting of an atom which releases more neutrons which cause more splitting’s and so on

Question 11

Understand the role played by the control rods and moderator when the fission process is used as an energy source to generate electricity.

Answer 11

The moderator slows down the speed of the neutrons so they can successfully collide
The control rods absorb some of the neutrons reducing speed of the chain reaction

Question 12

Explain the sources of background radiation

Answer 12

Cosmic Rays (from the sun); Rocks and Soil; Hospitals; Living Organisms

Question 13

Understand that the activity of a radioactive source decreases over a period of time and is measured in becquerels

Answer 13

The radio activity decreases over time as when the atom decays it stop releasing energy so over time there is less and less isotopes to release energy

Question 14

Understand the term ‘half-life’ and understand that it is different for different radioactive isotopes

Answer 14

This is the amount of time taken for the number or nuclei in a radio active sample to half, therefore it’s a constant

Question 15

Describe the structure of an atom in terms of protons, neutrons and electrons and use symbols such as 14 C to describe particular nuclei

Answer 15

Protons (+) and neutrons are in the nucleus of an element. Electrons (-) orbit on shells