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- State that radioactive emissions occur randomly over space and time.
Yep. Radioactive emission occurs randomly over space and time.
- Recall for radioactive emissions, and use to identify them:
• their nature
• their relative ionising effects
• their relative penetrating abilities.
Radiation from radioactive substances knocks electrons out of atoms. The atoms become charged (positively, since there will be more protons than electrons) and thus becomes ‘ionised’. This process is called ionisation. Ionisation in a living cell can damage or kill the cell, hence radiation is considered very dangerous.
Alpha radiation is a stream of alpha particles, which are positively charged (two protons and two neutrons). They’re large, which means they can’t easily pass through materials like cloth and paper. They also have the greatest ionising effect.
Beta radiation is a stream of beta particles, which are negatively charged (one electron). These particles can more easily penetrate materials like aluminium; they can even penetrate your skin where and thus body cells. But they can be blocked with denser materials like aluminum. Beta particles have lesser ionising effect than alpha particles.
Gamma radiation is high-frequency electromagnetic radiation. Gamma rays have no charge but have a lot of energy; more energy than even visible light or X-rays. Because of this, they are able to pass through most materials. But they can’t penetrate very dense materials like lead. Gamma rays, since uncharged and very fast-moving, have very less ionising effect.
- Describe the deflection of α-particles, β-particles and γ-rays in electric fields and magnetic fields
When alpha particles are released into an electrical field or magnetic field, it will deflect towards the negative pole or domain since they’re positive (opposite charges attract). Beta particles deflect towards the positive pole or domain. Gamma rays will not deflect to either side as they’re uncharged.
- Interpret their relative ionising effects.
Alpha particles have a huge mass and so travel slowly. This means that it has more effect on the atoms it encounters and causes a lot of ionisation.
Beta particles are lighter than alpha particles and moves faster and so have lesser ionising effect.
Gamma rays have very less ionising effect because they are uncharged and are very fast.
Notes submitted by Lintha
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