Characteristics of the three types of emission

Question 1

Radiation consists of ____________ emitted from the nucleus of an unstable atom.

Answer 1

high energy particles (or waves)

Question 2

There are three (main) types of radiation:

Answer 2

alpha (α) particles, beta (β−) particles, or gamma (γ) rays

Question 3

Radiation is emitted ___________

Answer 3

randomly
This means that, although we understand why some nuclei emit radiation, it is impossible to predict exactly when a nucleus will emit radiation

Question 4

Alpha (α) particles are

Answer 4

high energy particles made up of 2 protons and 2 neutrons (the same as a helium nucleus).

They are usually emitted from nuclei that are too large

Question 5

Beta (β−) particles are

Answer 5

high energy electrons emitted from the nucleus (even though the nucleus does not normally contain any electrons)
They are usually emitted by nuclei that have too many neutrons

Question 6

Gamma (γ) rays are

Answer 6

1. high energy electromagnetic waves
2. They are emitted by nuclei that need to lose some energy
3. If these particles hit other atoms, they can knock out electrons, ionising the atom

Question 7

When radiation passes close to atoms, it can knock out electrons, _________ the atom

Ionisation can cause chemical changes in materials, and can damage or kill living cells

Answer 7

ionising

Question 8

Charateristics summarized

Answer 8

Question 9

As the range and penetration increase, but the ionisation ____________

Answer 9

decreases

Question 10

Because they have opposite charges, alpha and beta particles are deflected in ___________ directions

Beta is deflected by more than alpha, because beta particles have a much ___________ mass

Gamma is not deflected because gamma rays have___________

Answer 10

opposite,smaller,no charge

Question 11

Alpha and Beta particles can also be deflected by magnetic fields. To find the direction of the deflection, we use ____________.

Answer 11

Flemings Left hand rule

Question 12

Alpha is by far the most _________of radiation

Alpha particles leave a dense trail of ions behind them, affecting virtually every atom they meet

Because of this they quickly lose their energy and so have a _________ range

Their short range makes them relatively harmless if handled carefully, but they have the potential to be extremely dangerous if the alpha emitter enters the body

Answer 12

ionising form, short,

Question 13

Beta particles are __________ ionising

The particles create a less dense trail of ions than alpha, and consequently have a ______ range

They tend to be more dangerous than alpha because they are able to travel further and penetrate the skin, and yet are still ionising enough to cause significant damage

Answer 13

moderately, Longer

Question 14

Gamma is the ________ ionising form of radiation (although it is still dangerous)

Because Gamma rays don’t produce as many ions as alpha or beta, they are more penetrating and have a __________ range

This can make them hazardous in large amounts

Answer 14

Least, longer

Question 15

Radioactive decay

Answer 15

is a random and spontaneous process in which an unstable nucleus will disintegrate into a more stable configuration by the emission of alpha-particles (helium nuclei), beta-particles (electrons) and/or gamma radiation (short-wavelength electromagnetic waves).

Question 16

radio-isotopes

Answer 16

Isotopes of an atom can be stable or unstable

A radioisotope has an unstable nucleus (too many neutrons and/or protons).

The unstable nuclei will try to become more stable by ejecting particles.

Question 17

Alpha Emission

Answer 17

An alpha particle consists of 2 protons and 2 neutrons
(It is emitted from large unstable nuclei)

When an alpha particle is emitted from a nucleus:

**The nucleus loses 2 protons:
The proton (atomic) number decreases by 2**

**The nucleus loses 4 particles (nucleons) in total:
The nucleon (mass) number decreases by 4**

Question 18

Beta Emission

Answer 18

A beta particle is a high energy electron emitted from the nucleus

• It is emitted when a neutron in the nucleus suddenly changes into a proton – an electron is created in order to balance the positive charge of the proton*
• *(Note: The electron is created at the moment of decay – it is not present in the neutron beforehand)**

When a beta particle is emitted from a nucleus:

The number of protons in the nucleus increases by 1:
The proton (atomic) number increases by 1

The total number of particles in the nucleus remains the same
The nucleon (mass) number doesn’t change

Question 19

Nuclear Fission

Answer 19

Usually large unstable nuclei break up gradually by the process of radioactive decay, but a small number (including Uranium-235, a naturally occurring isotope of Uranium) can break up in one big go – a process known as nuclear fission

Question 20

Nuclear Fusion

Answer 20

Nuclear fusion involves taking small nuclei (such as hydrogen) and colliding them together at high speed to form larger nuclei

Question 21

describe, with the aid of a block diagram, one type of fission reactor for use in a power station

Answer 21

Question 22

discuss theories of star formation and their energy production by fusion.

Answer 22

1. (Nebula stage) Stars form when enough dust and gas clump together
2. (protostar stage) This cloud of dust and gas starts to collapse due to its own gravitational forces. This gravitational force pulls the dust and gas together. As the gas falls together, it gets hot.
3. (Fusion stage) A star forms when it is hot enough for nuclear reactions to start. This releases energy, and keeps the star hot.

Question 23

Radioactive emission is random and ____________.

Answer 23

Spontaneous

its is unaffected by any physical or chemical variable in the environment.

The radioactive process cannot be slowed down or speeded up by anything.