TOPIC 4//Atomic Structure

Question 1

What are isotopes

Answer 1

Atoms of same elements which have same number of protons and but different number of neutrons

Question 2

What is radioactive decay

Answer 2

When other unstable isotopes tend to decay into other elements and emit radiation as they try become more stable

Question 3

Define radioactive

Answer 3

Unstable elements that can decay

Question 4

What do Radioactive substances do

Answer 4

They spit out one or more types of ionising radiation from their nucleus and release neutrons when they decay to reduce their mass and turn into energy

Question 5

What is ionising radiation

Answer 5

It is a radiation emitted from unstable nuclei that knocks off electrons from atoms creating positive ions

Question 6

What does Radioactive substances do when they decay

Answer 6

Release neutrons

Question 7

What are Alpha particles

Answer 7

Helium nuclei
An a-particle is 2 neutrons and 2 protons.

Question 8

What is 4 facts about an Alpha Radiation

Answer 8

1. alpha particle is emitted from the nucleus.
2. They dont penetrate very far into materials and are stopped quickly.
3. Because of their size they are strongly ionising.
4. Absorbed by a sheet of paper

Question 9

Why is Alpha radiation used in smoke detectors

Answer 9

It ionises air particles causing a current to flow

Question 10

What are Beta Particles

Answer 10

High speed electrons released by the nucleus
Beta particles have virtually no mass and a charge of -1

Question 11

What are 4 facts about Beta Radiation

Answer 11

1. Moderately ionising
2. They penetrate moderately far into materials before colliding because they have small mass and high speed
3. Every beta particle emitted, a neutron in the nucleus decays into a proton and a electron.
4. Absorbed by a sheet of metal/aluminium

Question 12

Why are Beta particles/Emitters used to test the thickness of sheets of metal

Answer 12

As the particles are not immediately absorbed by the material and do not penetrate far into materials

Question 13

What are Gamma Rays

Answer 13

EM waves with a short wavelength

Question 14

What are 3 facts about Gama rays

Answer 14

1. They penetrate far into materials without being stopped and will travel long distance through air
2. Weakly ionising because they tend to pass through rather than collide with atoms
3. Absorbed by lead/concrete

Question 15

What does nuclear equations show

Answer 15

shows us what is produced when a radioactive nucleus decays

Question 16

Nuclear equation for Beta decay

Answer 16

Atomic number increase by 1 and Mass number stays the same

Question 16

Nuclear equation for Alpha decay

Answer 16

atomic number reduces by 2 and mass number reduce by 4

Question 17

What do radioactive substances give out

Answer 17

Give out radioactive substances from nuclei of their atoms

Question 18

How can radiation be measured per second

Answer 18

Geiger Muller tube and counter

Question 19

What is meant by Radioactive decay

Answer 19

When a unstable nuclei loses energy by radiation ( Radioactive decay is completely random )

Question 20

Define half life

Answer 20

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

Question 21

What does a short half life mean

Answer 21

The activity falls quickly because the nuclei are very unstable and rapidly decay

Question 22

Why can a short half life be dangerous

Answer 22

Because of the high amount of radiation they emit at the star and quickly become safe

Question 23

What does a long half life mean

Answer 23

The activity falls slowly because most of the nuclei dont decay for a long time

Question 24

Why can a long half life be dangerous

Answer 24

Because the source just sits there releasing small amounts of radiation for a long time so nearby areas are exposed to radiation for millions of years

Question 25

What is contamination

Answer 25

Unwanted radioactive particles getting onto or into an object

Question 26

Why is contamination dangerous

Answer 26

.Radioactive particles could get inside your body. These contaminating atoms might then decay releasing radiation which could cause you harm