P4

Question 1

What is the size of the radius of an atom?

Answer 1

1×10^-10 m

Question 2

What is in the nucleus of an atom?

Answer 2

Protons (+) and neutrons (neutral)

Question 3

What is around the nucleus of an atom?

Answer 3

Electrons (-) In energy levels

Question 4

How does distance from nucleus affect energy levels?

Answer 4

Energy levels which are further from the nucleus are at higher energy than those close

Question 5

What happens if an atom, absorbs electromagnetic radiation

Answer 5

An electron can move from a lower energy to a higher energy level temporarily

Question 6

What is the atomic number and what does it tell us?

Answer 6

23
— Na
11 ————> atomic number
= number of protons,electrons

Question 7

What is the mass number and what does it tell us?

Answer 7

23 ———> mass number
— Na = number of protons
11. +Neutrons

Question 8

How do we calculate number of neutrons in an atom?

Answer 8

Mass number - the atomic number

Question 9

What are isotopes?

Answer 9

Isotopes are atoms of the same element that have different numbers of neutrons

Question 10

What are ions?

Answer 10

charged Atoms that lost or gained electrons from the outer energy level

Question 11

What is the plum pudding model?

Answer 11

An atom is a ball of positive charge with negative electrons embedded in it

Question 12

What is the alpha scattering experiment?

Answer 12

scientist, got a piece of gold foil and fired tiny particles (alpha particles of gold) at it

Question 13

What did the Alpha scattering experiment tell us?

Answer 13

-Atoms are mainly empty space most alpha particles went straight through the gold
-Due to some of the atoms deflecting atoms must have a positive charge
-Due to some alpha particles bouncing back, the mass of an atom must be concentrated in the centre

Question 14

What did James Chadwick discover?

Answer 14

The nucleus also contains neutrons

Question 15

What is radioactive decay?

Answer 15

When an isotope gives out radiation from the nucleus to become stable

Question 16

What is activity?

Answer 16

The activity is the rate at which is sort of unstable, nuclei decay
1 Bq = 1 decay per second

Question 17

How do we measure the activity of a radioactive source?

Answer 17

Geiger - muller tube

Question 18

What is count rate?

Answer 18

The count rate is the number of decays recorded each second by detectors such as Geiger-Müller tube

Question 19

What are the four types of radiation released by an unstable nucleus?

Answer 19

-Alpha(2 proton 2 neutron)same as helium
-Beta particle (Electron injected from nucleus at very high speed)
-Gamma rays (electromagnetic radiation from nucleus)
-neutron

Question 20

Where is a beta particle formed?

Answer 20

Inside the nucleus, when a neutron turns into a proton and electron

Question 21

What is the range in air between alpha particles?

Answer 21

Alpha particles are very large, they travel 5 cm before colliding with air

Question 22

What is the range in air of beta particles?

Answer 22

Beta particles travel 15cm

Question 23

What is the range in air between gamma rays?

Answer 23

Gamma rays can travel several metres

Question 24

What is the penetrating power of alpha particles?

Answer 24

Alpha particles are stopped by a single sheet of paper

Question 25

What is the penetrating power of beta particles?

Answer 25

Beta particles are stopped by a few millimetre of aluminium

Question 26

What is the penetrating power of gamma rays?

Answer 26

Gamma rays radiation is stopped by several centimetres of lead

Question 27

What is the ionising power of alpha particles?

Answer 27

Alpha particles are very strongly ionising

Question 28

What is the ionising power of beta particles?

Answer 28

Beta particles are quite strongly ionising

Question 29

What is the ionising power of gamma rays?

Answer 29

Gamma rays are weakly ionising

Question 30

What is ionising power?

Answer 30

When radiation collides with atoms ,that can cause loss of electrons and form ions

Question 31

What happens during alpha decay?

Answer 31

Atomic number decreases by 2 mass number decreases by 4

Question 32

Happens during beta decay

Answer 32

Atomic number increases by one and mass number does not change

Question 33

What happens during gamma decay?

Answer 33

Nothing both the atomic number and mass number ate not changed

Question 34

What is a half life?

Answer 34

time taken for -number of nuclei to decrease by half -count rate decrease by half

Question 35

What is irradiation?

Answer 35

Exposing an object to nuclear radiation a good example is sterilisation

Question 36

What is the risk to humans of ionising radiation?

Answer 36

Ionising radiation can increase risk of cancer

Question 37

What can we use as shielding (protection) against alpha beta and gamma rays?

Answer 37

For alpha rays, we can use gloves for beta and Gamma rays we can use lead apron and lead

Question 38

What is radioactive contamination?

Answer 38

When unwanted radioactive isotope end up on other materials

Question 39

Why is contamination hazardous?

Answer 39

Atoms decay, and emit ionising radiation

Question 40

What is peer review?

Answer 40

Studies are published in the scientist, allowing findings to be checked for legitimacy

Question 41

what is an alpha particle

Answer 41

2 charged atoms, 2 neutral atoms

Question 42

what charge does beta particles have

Answer 42

negative