P7

Question 1

Where in the atom does nuclear radiation come from

Answer 1

The nucleus

Question 2

What is ionising radiation

Answer 2

Radiation that changes an atom into an ion

Question 3

What can ionising radiation cause

Answer 3

Cancer- mutates dna and kills cells

Question 4

What is radiation

Answer 4

The particles or waves being emmited by radioactive substances

Question 5

In a radioactive atom, why are particles or waves emmited

Answer 5

The nucleus is unstable and so it emits particles or waves to form a more stable atom. This process is called radioactivity or radioactive decay

Question 6

What is nuclear fission

Answer 6

Big nuclei being split into 2 or more daughter nuclei

Question 7

What is nuclear fusion

Answer 7

2 smaller atoms joining together - making a bigger atom / nucleus

Question 8

When was daltons’s model of the atom

Answer 8

1808

Question 9

What did dalton come up with

Answer 9

All matter is made up of tiny spherical atoms, atoms can’t be broken into smaller parts, atoms of particular elements are identical and differ from those of other elements

Question 10

When was JJ thompsons plum pudding model discovered

Answer 10

1904

Question 11

What did jj thompson come up with

Answer 11

He knew there were electrons, he knew there was no electric charge so he came up with a sphere of positive charge with electrons evenly distributed

Question 12

When was rutherfords nuclear model of the atom discivered

Answer 12

1911

Question 13

3 of rutherfords observations

Answer 13

• Most alpha particles went straight through meaning most of the atom is empty space
• some particles are deflected meaning the nucleus is very small and in the centre
• very few particles are repelled back meaning the nucleus is positively charged

Question 14

What does an alpha particle contain

Answer 14

2 protons and 2 neutrons

Question 15

When was bohr’s plantenary model of the atom discovered

Answer 15

1914

Question 16

What did bohr discover

Answer 16

The electrons are aranged in shells which orbit the nucleus. They can move between shells by emitting or absorbing electromagnetic radiation

Question 17

3 reasons as to why some atoms are radioactive

Answer 17

• nucleus is unstable
• the nucleus has too many neutrons or not enough
• nucleus is too big and wants to break up

Question 18

What is a radioisotope

Answer 18

The nucleus of isotope is unsavke

Question 19

What is activity?

Answer 19

The number of unstable nuclei that decay every second

Question 20

What is Count-rate?

Answer 20

The number of decays recorded each second by a detector

Question 21

What is half-life?

Answer 21

The time that it takes half the atom in a sample to decay

Question 22

What process is radioactive decay?

Answer 22

Spontaneous (can’t be controlled and not affected by temperature)

Question 23

How is alpha radiation stopped?

Answer 23

By paper

Question 24

How is beta radiation stopped?

Answer 24

A sheet of aluminium a few metres thick

Question 25

How are gamma rays stopped?

Answer 25

Thick walls of concrete or lead

Question 26

Why was rutherfords model accepted?

Answer 26

-agreed exactly with the measurements geiger and marsden made in their experiements -explained radioactivity in terms of changes that happen to an unstable nuclei when emmiting radiation -predicited existence of neutrons

Question 27

Problems with the plum pudding model:

Answer 27

Could not explain why some alpha particles were scattered through large angles

Question 28

Radioactive decay

Answer 28

An unstable nucleus becoming more stable by emitting alpha or beta particles

Question 29

Why are most nuclei stable?

Answer 29

Because the protons and neutrons inside a nucleus are held together by a string nuclear force

Question 30

Irridated

Answer 30

When an object is exposed to ionising radiation, but does not hecome radioactive

Question 31

Radioactive contamination

Answer 31

Unwanted presence of materials containing radioactive atoms on other materials

Question 32

What may cause ionisation?

Answer 32

X-rays, fast moving protons and neutrons

Question 33

How do workers who use ionising radiation reduce their exposure?

Answer 33

-keep as far away as possible from the source -spending little time in at-risk areas -sheilding themselves by staying behind thick concrete barriers

Question 34

Example of radiation in use:

Answer 34

Smoke alarms (contain the radioactive isotope that sends out alpha particles in a circuit)

Question 35

Current model of the atom:

Answer 35

-radius of atom is 1x10^-10 -electrons in energy levels move within the atom -if they gain energy by absorbing EM radiation, they move to a higher energy level

Question 36

What do unstable isotopes do to other elements?

Answer 36

They tend to decay into other elements and give out radiation as they try to become more stable (radioactive decay)

Question 37

What does ionising radiation do to electrons?

Answer 37

It knocks them off atoms, creating positive ions. The ionising power of a radiation source is how easily it can do this

Question 38

Nuclear equations:

Answer 38

Atom before decay ➡️ atom after decay + radiation emitted

Question 39

Risks of ionising radiation:

Answer 39

It can enter living cells, damage them or kill them

Question 40

Irradiation

Answer 40

Exposure to radiation

Question 41

How to control irriadation:

Answer 41

-The source may be in a different room and remote control arms are used to handle it -keeping sources in lead-lined boxes --standing behind barriers

Question 42

How is something contaminated?

Answer 42

If unwanted radioactive atoms get onto, or into an object

Question 43

Example of contamination:

Answer 43

If you touch a radioactive source without wearing gloves

Question 44

How can you reduce contamination?

Answer 44

-Wear gloves and use tongs -wear protective suits

Question 45

Why are alpha particles less dangerous?

Answer 45

It can't penetrate skin

Question 46

How are alpha particles dangerous in the body?

Answer 46

-They damage very localised areas so contaminate them

Question 47

How are beta particles less damaging in the body?

Answer 47

Radiation is absorbed over a wider area and some passes out the body altogether

Question 48

How are gamma sources not dangerous in the body?

Answer 48

-they mostly pass straight out and have the lowest ionising power