Radioactive Decay

Question 1

What did Marie Curie discover?

Answer 1

All uranium compounds are radioactive and contain two other elements; polonium and radium.

Question 2

What is natural radioactivity

Answer 2

The process where substances emit radiation freely in nature

Question 3

Why could the nuclei of some atoms be unstable?

Answer 3

They may have too much energy or the wrong number of particles in the nucleus

Question 4

How do atoms make themselves more stable?

Answer 4

They emit particles and/or energy from the nucleus

Question 5

What happens if a nucleus emits a particle

Answer 5

It becomes the nucleus of a different element. This is radioactive decay

Question 6

What are the particles given out during radioactive decay called?

Answer 6

Radiation or radioactive emissions

Question 7

What is radioactivity

Answer 7

The spontaneous (random) decay of the nuclei of atoms by emission of particles and/or energy

Question 8

How did Henri Becquerel discover that uranium compounds emit radiation spontaneously?

Answer 8

He left a piece of uranium in his drawer next to a photographic plate wrapped in black paper. This plate showed a darker section when it was developed; a shadow had formed, indicating something was been emitted (radiated) from the uranium that would effect photographic film.

Question 9

What is ionisation?

Answer 9

When radiations hits a neutral atom, some of the energy from the radiation is passed to the atom. This energy can cause an electron from the atom to escape, leaving the atom with a positive charge. This positively charged atom is an ion, and this process is called ionisation.

Question 10

Why can ionisation be dangerous?

Answer 10

It is ionisation that makes radioactive substances so dangerous. Living cells can be damaged if molecules in the cell are ionised, and this can kill cells or cause radiation burns and cancers. (It damages DNA.) the more radiation, the more likely it is that cancer will occur

Question 11

All atoms are made up of..

Answer 11

Protons, neutrons and electrons

Question 12

What is the only difference between one atom and the next?

Answer 12

The number of protons, electrons and neutrons in the atom.

Question 13

How much do neutrons and protons way in comparison to electrons

Answer 13

2000 times as much as an electron

Question 14

What charge to protons have

Answer 14

Positive

Question 15

What charge to electrons have

Answer 15

Negative

Question 16

What charge to neutrons have

Answer 16

No charge

Question 17

How would you describe an atom?

Answer 17

It is not a solid thing. Protons and neutrons are tightly held together by a strung nuclear force in the nucleus and electrons spin around them.

Question 18

Are atoms almost full, or almost empty?

Answer 18

Almost empty

Question 19

How would you describe an atomic structure

Answer 19

There is a specific notation used to describe the number and type of particles associated wit jam atom.
Eh,
4 = mass number
   He
2 = number of protons

Question 20

What is the mass number?

Answer 20

How many particles are in the nucleus (how many protons and neutrons)

Question 21

What is the atomic number

Answer 21

How many protons there are in the nucleus

Question 22

What does it mean if an atom is neutral

Answer 22

The number of electrons in an atom is the same as the number of protons

Question 23

What happens if the numbers of protons and electrons am atom are not equal

Answer 23

It becomes a charged particle ion

Question 24

All atoms of a certain element will have…

Answer 24

The same number of protons in the nucleus

Question 25

What do the number of protons on an element decide?

Answer 25

How the elements is going to behave chemically and therefore what element the atom belongs to. If the number of protons in an atom changes, the type of atom is changed. (It becomes an atom of another element)

Question 26

What is an isotope?

Answer 26

Isotopes have the same number of protons but a different number of neutrons

Question 27

What is the symbol for alpha particles?

Answer 27

4 α 2 Or 4 He 2

Question 28

What is the symbol for beta particles?

Answer 28

In beta radiation, a neutron in the nucleus split up into a proton plus an electron. The proton stays in the nucleus and the electron is ejected at high speed, so 0 β -1 Or 0 e -1

Question 29

What is the symbol for gamma rays?

Answer 29

Also known as electro-magnetic radiation γ (no charge, no mass, no nothing)

Question 30

Why do particles that ionise strongly have a low penetrating power?

Answer 30

They lose energy each time they ionise an atom

Question 31

Is radioactive decay affected by external conditions?

Answer 31

No

Question 32

Charge of an alpha particle

Answer 32

+ 2

Question 33

Charge of a beta particle

Answer 33

- 1

Question 34

Charge of a gamma ray

Answer 34

0

Question 35

Speed of an alpha particle

Answer 35

Slow

Question 36

Speed of a beta particle

Answer 36

Fast

Question 37

Speed of a gamma ray

Answer 37

Very fast

Question 38

Ionising ability of an alpha particle

Answer 38

High

Question 39

Ionising ability of a beta particle

Answer 39

Medium

Question 40

Ionising ability of a gamma ray

Answer 40

Low

Question 41

Penetrating power of an alpha particle

Answer 41

Low

Question 42

Penetrating power of a beta particle

Answer 42

Medium

Question 43

Penetrating power of a gamma ray

Answer 43

High

Question 44

What is an alpha particle stopped by

Answer 44

Paper

Question 45

What is a beta particle stopped by

Answer 45

Aluminium

Question 46

What is a gamma particle stopped by

Answer 46

Lead

Question 47

What are nuclear decay equations used to describe

Answer 47

The decay of nuclei by emission of radioactive particles and the product nuclei

Question 48

What do nuclear decay equations have to balance

Answer 48

- the total number of protons must be the same before and after the reaction - the total number of nucleons must be the same before and after the reaction

Question 49

In alpha decay, the product nuclei has...

Answer 49

Two less protons and two less neutrons

Question 50

In beta decay, the product nuclei has...

Answer 50

One more proton and one less neutron

Question 51

are gamma rays emitted with change of nuclei

Answer 51

No

Question 52

Why does the nucleus emit an electron when it emits a beta-particle?

Answer 52

The neutron has changed into a proton and an (emitted) electron

Question 53

Where is background radioactivity

Answer 53

All around us in the atmosphere.

Question 54

Where does background radioactivity come from?

Answer 54

Radioactive rocks in the ground, radon gas in the air and cosmic rays from outer space

Question 55

What do you use to detect radioactivity

Answer 55

A Geiger counter. It clicks each time a particle of radiation from a radioactive substance enters the Geiger tube.

Question 56

What does the number of clicks per second represent I'm a Geiger counter

Answer 56

The activity of the sample. The higher the activity the more radioactive the sample

Question 57

How would you accurately measure the activity of a sample of a radioactive substance

Answer 57

First measure the background radioactivity. This can then be subtracted from the measured sample activity to obtain a true reading

Question 58

What is the half life of a substance?

Answer 58

The amount of time it takes for half of the atoms in a sample to decay. This can vary from being less than a second to taking millions of years

Question 59

What is the half life for a given isotope

Answer 59

Always the same

Question 60

What does a half-life not depend on

Answer 60

How many atoms you being with

Question 61

What does the half life of an elect indicate

Answer 61

How stable an isotope is. The longer it takes to decay, the more stable it is

Question 62

What is decays per second measured in

Answer 62

Becquerel's (Bq)