Radioactivity and Nuclear Reactions

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It took them >3 years to get 0.1g of radium from several tons of the mineral pitchblende.

Slide 31

Nuclear Decay

What You’ll Learn

How alpha, beta, and gamma radiation are similar and different

What the half-life of a radioactive material is

How radioactive dating is used

Slide 32

Nuclear Radiation

When an unstable nucleus decays, it breaks apart emitting particles and energy as it decays.

Slide 33

Nuclear Radiation

When an unstable nucleus decays, it breaks apart emitting particles and energy as it decays.

Three types of nuclear radiation:

Alpha particles

Beta particles

Gamma radiation electromagnetic wave

Slide 34

Alpha Particles

An alpha particle is made of 2 protons & 2 neutrons.

Slide 35

Alpha Particles

An alpha particle is made of 2 protons & 2 neutrons.

The decaying nucleus emits an alpha particle ( 42He) with a mass number of 4 & atomic number of 2.

Slide 36

Alpha Particles

An alpha particle is made of 2 protons & 2 neutrons.

The decaying nucleus emits an alpha particle ( 42He) with a mass number of 4 & atomic number of 2.

An alpha particle is the same as the nucleus of a Helium (He) atom.

Slide 37

Alpha Particles

Alpha particles have much more mass than beta or gamma radiation

with an electric charge of +2.

Penetrate or pass through matter

Attract negatively charged electrons away from atoms they pass

Lose energy quickly & slow down

Heavier & move more slowly than β or gamma

Sheet of paper can stop alpha particles

Slide 38

How can alpha particles harm you?

Think of alpha particles like bowling balls moving in slow motion – they may not penetrate deeply but they can do lots of damage to whatever they hit.

Released inside the human body they can damage cells causing illness & disease.

Slide 39

How can alpha particles help you?

Smoke detectors work by emitting alpha particles which collide with molecules in the air forming ions that flow within the detector to create an electric circuit. Smoke particles break this circuit causing the alarm to sound.