AlphaBeta

Gamma

AlphaBeta

Gamma

Lesson ContentsLesson Contents1. What is Radioactivity?2. Physical properties of ,

and 3. Penetrating power

of,and4. N v Zgraphs (for fun)5. Decay laws

Early Pioneers in Radioactivity

Roentgen:

Discoverer of X-rays 1895

Becquerel:

Discoverer of Radioactivity

1896

The Curies:

Discoverers of Radium and

Polonium 1900-1908

Rutherford:

Discoverer Alpha and Beta

rays 1897

Villard:

Discovery of gamma rays 1898-1900

What do we mean by Radioactivity?

Radioactive decay is the process in which an unstable atomic nucleus

loses energy by emitting radiation in the form of particles or

electromagnetic waves.

The general idea:

An unstable nucleus releases energy to become

more stable

Radioactivity – Is it a Health Problem?

•The Alpha, Beta and Gamma particles all add

energy to the body’s tissues. It can alter

DNA.

• http://www.youtube.com/watch?v=5oUagoF_viQ

Alpha Radiation Alpha Radiation Alpha particles contain two protons and two neutrons

Alpha RadiationAlpha Radiation has the same constitution as

a Helium nucleusAlpha particles may be written

as

Beta-minus RadiationBeta-minus RadiationBeta-minus particles are electrons

Beta-minus RadiationBeta-minus Radiation- is produced when a neutron

decaysBeta-minus particles may be

written as

Beta-minus RadiationBeta-minus Radiation

- is produced when a neutron decays

The surplus mass is released as kinetic energy in the - and

as an antineutrino

Hulk SMASH!!!!

• http://www.youtube.com/watch?v=jv95T-5bSYk

Gamma RadiationGamma RadiationGamma rays are a form of electro-magnetic radiation

Gamma RadiationGamma Radiation release is often associated

with or decayGamma rays remove energy from an unstable nucleus.

Has no mass and no charge.

O

O

Penetrating powerPenetrating power

• http://www.youtube.com/watch?v=5oUagoF_viQ

N v Z graphsN v Z graphsA Graph of neutron number (N) against proton number (Z) helps to predict whether an isotope will emit or -

radiation

N v Z graphsN v Z graphsIsotopes in this region emit particles to become more stable.N decreases by 2Z decreases by 2

N v Z graphsN v Z graphsIsotopes in this region emit particles to become more stable.N decreases by 1Z increases by 1

Decay laws - alphaDecay laws - alphaWhen an isotope emits an particle Its nucleon number decreases by 4 Its proton number decreases by 2For example:

Decay laws – beta-minus

Decay laws – beta-minus

When an isotope emits a- particle Its nucleon number is unchanged Its proton number increases by 1For example:

Decay lawsDecay lawsTry writing the nuclear equations for the decay of these isotopes

Decay lawsDecay lawsAnswers

2 6

14 28

50 82

126

•Stability is not Stability is not usually achieved usually achieved in a single stepin a single step

•When a When a radioactive radioactive

nucleus reaches nucleus reaches a stable state by a stable state by a series of steps, a series of steps,

we call it a we call it a decay seriesdecay series

Hulk sad the PowerPoint is over,

Hulk no wanna leave.