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33 Cards in this Set
- Front
- Back
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Who discovered Polonium?
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Marie Curie
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What tool do we use to measure radioactivity?
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Geiger counter
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What are the three types of radiation?
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1. Alpha
2. Beta 3. Gamma |
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What material absorbs alpha radiation?
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Paper
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What material absorbs beta radiation?
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aluminium foil
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What material absorbs gamma radiation?
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a few centimeters of lead
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why are only some substances radioactive?
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as most substances have stable nuclei and radioactive substances are trying to become stable by emitting radiation
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what causes background radiation?
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1. the environment
2. cosmic rays 3. devices such as x ray tubes |
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why can we not predict radioactive decay?
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as it is a random event that we cant predict or influence
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what charge dose the nucleus have?
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Postive
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What was the plum pudding model?
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a model of an element that believed that the electrons were in a sea of positive charge.
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what was wrong with the plum pudding model?
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it could not explain why some alpha particles scattered
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where is most of the mass found in the atom
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the nucleus
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what is an isotope?
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an isotope is an element with the same number of protons but different number of neutrons changing the mass number
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what change in the nucleus happens in alpha decay?
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the nucleus loses 2 protons and 2 neutrons ( a helium atom)
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what change in the nucleus happens in beta decay?
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a neutron in the nucleus changes in to a proton
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what happens when a particle is emitted in alpha decay?
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2 protons and 2 neutrons are emitted as an alpha particle.
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what happens when a particle is emitted in Beta decay?
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an electron is created in the nucleus and is immediately emitted.
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what is the order of penetrating power?
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1. gamma
2. beta 3. alpha |
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what is alphas range in air?
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5cm
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what is Betas range in air?
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1 m
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what is gamma range in air?
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unlimited
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why is beta radiation easily deflected
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as it is a negatively charged particle (electron)
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what direction dose beta deflect in comparison to alpha?
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the opposite direction as it is positively charged
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is gamma radiation affected by magnetic fields?
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no as it is a wave not a particle and therefore has no charge.
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why do alpha particles deflect less than beta
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as alpha ways 8000 times more than beta canceling out the fact that alpha has twice the attraction.
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what is ionisation ?
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when a partlice gets an electron knocked of by a radioactive substance.
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why is ionisation dangerous?
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it can kill or damage cells that can cause problems such as cancer.
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which is the most dangerous if it some how finds its way in to the body?
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alpha as it has the greatest ionising power causing the greatest damage to the cells
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how can we seperate radiation?
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Using magnetic fields
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what is a half life?
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the average time it takes for the number of a nuceli of the isotope to half
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what is radioactivity activity?
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number of nucli that decay per second
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how much dose the count and number of istopes change every half life
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by half eg. 300 --> 150
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