P7

Question 1

Who made the plum pudding model and when?

Answer 1

J.J Thomson in 1904

Question 2

What does the plum pudding model look like

Answer 2

A round positively charged atom with electrons scattered inside it

Question 3

What was rutherford’s expirement?

Answer 3

He sent a beam of alpha particles through a small piece of gold foil.

Question 4

What were Rutherford’s observations

Answer 4

-Most of the alpha particles passed through the gold foil
-Some were deflected off at different angles
-Some were repelled straight backwards

Question 5

Who discovered radioactivity

Answer 5

Henri Becuerel

Question 6

What do the observations mean

Answer 6

-The atom is mostly empty space
-The nucleus is positively charged
-The nucleus carries most of the atoms mass

Question 7

Radiation definition

Answer 7

The release of energy in the form of moving waves or stream of particles

Question 8

What is the mass number

Answer 8

On Top (Bigger) Number = Neutrons + Protons

Question 9

What is the atomic number

Answer 9

Bottom (smaller) number = number of protons and electrons

Question 10

Who adapted Rutherford’s Model

Answer 10

Bohr

Question 11

Who proved the existence of the Nucleus

Answer 11

Chadwick

Question 12

What is an isotope

Answer 12

An atom with a different number of neutrons

Question 13

What is a radioisotope

Answer 13

an isotope which has an unstable nucleus. It will decay by emitting radiation.

Question 14

What is the Unit for radioactivity

Answer 14

Becquerels = 1 decay event per secomd

Question 15

Properties of Alpha radiation

Answer 15

-Large
-5cm travel range before colliding
-Can be stopped by single sheet of paper
-Very ionising

Question 16

Properties of Beta radiation

Answer 16

-1m travel range before colliding
-harder to stop few millimetres of aliminium
-Quite ionising

Question 17

Properties of Gamma Radiation

Answer 17

-Travel range unlimited
-Can only be stopped by Several centimetres of lead
-weak ionising power

Question 18

What is ionising power

Answer 18

When radiation collides can cause atoms to lose electrons and form ions

Question 19

What is the most dangerous form of radiation

Answer 19

Alpha radiation because they have the largest mass and charge so they are the most ionising

Question 20

Why are gamma rays non ionising

Answer 20

Because they barely interact with electrons

Question 21

Dangers of radioactivity

Answer 21

Irradation and contamination

Question 22

What is irradiation

Answer 22

Exposing of an object to nuclear radiation

Question 23

Pre cautions for radiation

Answer 23

Lead apron
Gloves
Lead barriers
Geiger counter

Question 24

What is contamination

Answer 24

When unwanted radioactive isotopes end up on other materials

Question 25

Peer review

Answer 25

Process by which scientists share their data with other scientists to get reviewed so it can then be published

Question 26

When an object is exposed to radiation does it become radioactive

Answer 26

No it becomes irradiated

Question 27

Uses of radioactivity

Answer 27

-Smoke alarms (uses alpha) -Measuring Paper thickness (uses beta)

Question 28

Why do smoke alarms use alpha radiation

Answer 28

Alpha has the least penetrating power Because beta and gamma cannot create enough ions to detect smoke

Question 29

Why do paper measures use beta radiation

Answer 29

-Because alpha wouldn't penetrate the paper -Because gamma would penetrate all of it Beta can measure change because if the paper gets too thick it won't pass through

Question 30

What are alpha particles made of

Answer 30

Helium nucleus

Question 31

What are Beta particles made of

Answer 31

Fast moving electron

Question 32

What are Gamma particles made of

Answer 32

Surplus Energy

Question 33

What is activity

Answer 33

The activity of a radioactive source is tye number of unstable nuclei that decay every second

Question 34

What happens to the activity of a source as more unstable atoms decay

Answer 34

Less unstable atoms so activity decreases

Question 35

What is count rate

Answer 35

Number of decays recorded each second by a detector (e,g geiger-muller tube)

Question 36

What is half-life

Answer 36

Half-life is the time takennfor hald of the atoms in a sample to decay

Question 37

Is radioactive decay affected by temperature

Answer 37

No its spontaneous

Question 38

What does a shorter half life mean

Answer 38

That the sample is more active

Question 39

What does a longer half life mean

Answer 39

Less active sample