GCSE Radioactivity PowerPoint Presentation

GCSE Radioactivity PowerPoint Presentation

1. RadioactivityRadioactivity

2. ContentsContents

Atomic StructureAtomic Structure

IsotopesIsotopes

Background RadiationBackground Radiation

Alpha, Beta, GammaAlpha, Beta, Gamma

Uses of RadiationUses of Radiation

Nuclear FissionNuclear Fission

Chain ReactionsChain Reactions

3. Atomic StructureAtomic Structure
Electron:
negative,
mass nearly
nothing
Proton:
positive, same
mass as
neutron (“1”)
Neutron:
neutral, same
mass as
proton (“1”)

4. IsotopesIsotopes
The atomic number controls which element it is.
e.g. Oxygen must always have 8 protons
Isotopes are the same element with a different mass
number. Isotopes have different numbers of neutrons
Radiation occurs when the mass number of an element changes

5. Background RadiationBackground Radiation
Radon gas
Food
Cosmic rays
Gamma rays
Medical
Nuclear power
13% are
man-made

6. Alpha, Beta, GammaAlpha, Beta, Gamma
Alpha (α): atom decays into a new atom
& emits an alpha particle (2 protons
and 2 neutrons: the nucleus of a helium
atom)
Beta (β): atom decays into a new atom
by changing a neutron into a proton &
electron. The fast moving, high energy
electron is called a beta particle
Gamma (γ): after α or β decay,
surplus energy is sometimes
emitted. This is called gamma
radiation & has a very high
frequency with short wavelength.
The atom is not changed
Unstable
nucleus
Unstable
nucleus
Unstable
nucleus
New
nucleus
New
nucleus
New
nucleus
Alpha
particle
Beta
particle
Gamma
radiation

7. Uses of RadiationUses of Radiation
β passes through paper,
card etc.
β passed through sheets to
a detector
When β count slows
material is too thick
α

γ
Sheet of paperThin foil Few cm of lead
γ kills microbes
Medical instruments sterilised
Food keeps fresh for longer
No damage to substances
Half-life short so no radiation
afterwards

8. Nuclear FissionNuclear Fission
Nuclear fission occurs when the mass number of an
element splits. The product is a new element and
released neutrons
Nuclear fission releases heat energy
This heat is harnessed in nuclear power stations to boil
water, which is used to drive turbines and machinery
The amount of energy produced by each reaction is very
small billions of reactions occur every second
The waste products from these reactions are radioactive,
which is why many people worry about nuclear power
plants

9. Uranium
nucleus
Unstabl
e
nucleus
New nuclei
(e.g. barium
and krypton)
More
neutrons
Neutro
n
Nuclear FissionNuclear Fission

10. Chain ReactionsChain Reactions

Each fission reaction releases neutrons
that are used in further (chain) reactions

11. SummarySummary

Nucleus = protons and neutrons; electrons are in shellsNucleus = protons and neutrons; electrons are in shells

Isotopes = same element with different mass numberIsotopes = same element with different mass number

Background radiation = many causes, some man-madeBackground radiation = many causes, some man-made

Alpha (highly ionising, low penetration), Beta (stopped by Alpha (highly ionising, low penetration), Beta (stopped by
a few mm of foil), Gamma (high penetration a few mm of foil), Gamma (high penetration  v v
dangerous)dangerous)

Uses of radiation (Beta: quality assurance, Gamma: Uses of radiation (Beta: quality assurance, Gamma:
medical instruments & food freshness)medical instruments & food freshness)

Nuclear fission = atom divides Nuclear fission = atom divides  releases neutrons releases neutrons

Chain reactions = result of released neutronsChain reactions = result of released neutrons