What is radioactivity?

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  • Created by: Lily04
  • Created on: 15-06-17 13:13
What does radioactivity do to materials?
Ionises them
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What happens to radiation over time ?
It decreases
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Where does radiation come from?
The nucleus of an unstable atom
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How is radiation measured?
A Geiger counter is used to detect the rate of decay of a radioactive substance. Each click or number on the display screen represents the decay of one nucleus.Activity is measured by counting the av. no. Of nuclei that decay every sec.- count rate
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Radioactive substances decay naturally and give out.....
Alpha, beta and gamma radiation
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True or false? Radioactive decay is a random process AND EXPLAIN
True- we cannot predict when a nucleus will decay. Decay is independent of physical conditions such as temperature.
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What is the formula used to measure the activity and what is it measured in?
Number of nuclei decay / time taken in seconds. Measured in counts per second or becquerels
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What is half life?
The half- life of a radioisotope is the average time it takes for half the nuclei present to decay. This is the time for the activity to half.
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A radioisotope has nuclei that are ....... because....
A radioisotope has nuclei that are unstable because its nuclear particles are not held together strongly enough
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What is the largest stable nucleus known and what does this mean?
An isotope of lead which is why it is often found near radioactive rocks
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What is an alpha particle?
Helium nucleus and consists of two protons and two neutrons, relatively large mass, positively charged
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What is a beta particle?
A high-speed electron- negatively charged, very small mass, travels very fast
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What is gamma radiation?
Electromagnetic wave
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Explain ionisation in terms of electron movement
When nuclear radiation strike some atoms of material it is passing through, it knocks negatively charged electrons out of atoms. The atoms have lost electrons so they are now positively charged , they are now positive ions.
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Explain why alpha particles are such good ionisers
Because it is missing two electrons (it has a 2+ charge) it attracts electrons away from atoms it passes, leaving the, positively charged.
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What happens to a nucleus during alpha decay?
The nucleus has 2 fewer Neutons, the nucleus has two fewer protons, the mass number decreases by four, the atomic no. Or proton no. Decreases by two. A new element is formed that is 2 places lower in the periodic table than the original radioisotope
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What happens to a nucleus during beta decay?
The nucleus has 1 more proton, 1 less neutron, the mass number is unchanged, the atomic no. Or proton no. Increases by 1 . A new element is formed that is 1 place higher on the periodic table than the original radioisotope
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In beta decay a neutron changes into a .... and charge is ...
Proton and an electron and charge is conserved
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What is a nucleon?
Is a particle in a nucleus. Protons and neutrons are nucleons.
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Other cards in this set

Card 2

Front

What happens to radiation over time ?

Back

It decreases

Card 3

Front

Where does radiation come from?

Back

Preview of the front of card 3

Card 4

Front

How is radiation measured?

Back

Preview of the front of card 4

Card 5

Front

Radioactive substances decay naturally and give out.....

Back

Preview of the front of card 5
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