1.      F/H

Some substances give out radiation all the time, whatever is done to them. These substances are said to be …….

radioactive

2.      F/H

Name the three types of radiation and describe how they can pass through materials such as paper or air

* alpha radiation - which is easily absorbed by a few centimetres of air or a thin sheet of paper; * beta radiation - which easily passes through air or paper but is mostly absorbed by a few millimetres of metal; * gamma radiation - which is very penetrating and requires many centimetres of lead or metres of concrete to absorb most of it.

3.      F/H

Name three sources of background radiation

the ground, in the air, in building materials and in food. Radiation also reaches us from space.

4.      F/H

When radiation from radioactive materials collides with  atoms  these may become ionised. Explain what this means

The neutral atoms may become charged

5.      F/H

What can this do to living cells?

it can cause damage, including cancer. The larger the dose of radiation the greater the risk of cancer.

6.      F/H

What can higher does of radiation do to cells? Give a use for this.

can kill cells; they are used to kill cancer cells and harmful micro-organisms - e.g sterilizing hospital equipment

7.      F/H

How can alpha or beta radiation be used to monitor the thickness of paper?

As radiation passes through a material it can be absorbed. The greater the thickness of a material the greater the absorption.

8.      H

Which sources of radiation are the most dangerous when outside th body?

* beta and gamma radiation are the most dangerous because they can reach the cells of organs and may be absorbed by them; * alpha radiation is least dangerous because it is unlikely to reach living cells.

9.      H

When inside the body, alpha radiation can be the most dangerous - why?

because it is so strongly absorbed by cells;

10.  H

what is the half-life of a radioactive substance

the time it takes for the number of parent atoms in a sample to halve OR the time it takes for the count rate from the original substance to fall to half its initial level.

11.  F/H

Radioactivity occurs as a result of changes in the electrons of atoms - TRUE or FALSE?

FALSE - it's the nucleus

12.  F/H

Atoms have a small central ………. made up of ………... and ……... around which there are ………..

nucleus, protons and neutrons, electrons

13.  F/H

describe the "plum pudding" model of the atom

it is an outdated model of the atom in which they thought the atom was a solid ball of positive charge with electrons scattered through it like currents in a pudding

14.  F/H

explain the scattering experiment by Rutherford's team

Rutherford found that alpha particles were scattered through large angles when fired though thin gold foil.  This could be best explained if the atom consists of a small central nucleus surrounded by electrons in orbit.

15.  F/H

Complete this table: particle:  mass:  charge: location in atom              Proton

                      Neutron

                      Electron

              Mass     Charge location

Proton      1          +1      in nucleus

Neutron   1            0       in nucleus

Electron   negligible  -1  in orbit around nucleus

16.  F/H

In an atom, the number of electrons is equal to the number of …….. in the ……... The atom as a whole has ….. electrical charge.

protons, nucleus, no

17.  F/H

All atoms of a particular element have the same number of ………... Atoms of different elements have different numbers of ………

protons, protons

18.  F/H

The total number of protons and neutrons (nucleons) in an atom is called its ……….. number.

mass or nucleon

19.  F/H

Atoms of the same element which have different numbers of neutrons are called ………

isotopes

20.  F/H

Radioactive isotopes are atoms with unstable ………When an unstable nucleus splits up it emits………… and a different atom, with a different number of ……..., is formed.

nucleus, radiation, protons

21.  F/H

The older a radioactive material, the ………..  radiation it emits. This idea can be used to date materials.

less

22.  H

Any isotope of an element which is radioactive is called a …………..

radioisotope (OR radionuclide).

23.  H

Alpha radiation consists of particles made up of two ………. and two ………..

protons, neutrons

24.  H

Beta radiation consists of ……... emitted from the ………. of atoms.

electrons, nuclei

25.  H

In Beta decay: for each ………. emitted, a ……….. in the nucleus becomes a ………..

electron, neutron, proton

26.  H

Gamma radiation is very short ………..electromagnetic radiation.

wavelength

27.  H

Nuclear reactors use a process called nuclear ……….. When an atom with a very large nucleus is bombarded with ………..

fission, neutrons

28.  H

What happens during this process?

* the nucleus splits into two smaller nuclei; * further neutrons are released which may cause further nuclear fission resulting in a chain reaction; * the new atoms which are formed are themselves radioactive.

29.  H

The  energy released  by  an atom  during  radioactive  disintegration  is  very …….. compared to the energy released when a chemical bond is made between two atoms.

large

30.  H

Uranium isotopes, which have a very long half-life, decay via a series of relatively short-lived radioisotopes to produce stable isotopes of ........ The relative proportions of ............and ........ isotopes in a sample of igneous rock can, therefore, be used to ..................................................................

lead, uranium and lead, date rocks

31.  H

The proportions of the radioisotope potassium-40 and its stable decay product argon can also be used to date……….. …………..  from which the gaseous ………... has been unable to escape.

igneous rocks, argon