PHYSICS RADIOACTIVITY

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what is A
total number of nucleus and known as mass number / nucleon number / atomic mass
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what is Z
total number of protons and known as atomic number / proton number
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what is X
chemical symbol for the element
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what is A-Z
number of neutrons
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ion
a charged atom which has had its number of electrons charged
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charge of proton
+1
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charge of neutron
0
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charge of electron
-1
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isotopes
atoms or nuclei that have the same number of protons but different numbers of neutrons
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alpha particles
made up of 2 protons and 2 neutrons
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beta particles
same as an electron
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gamma rays
electromagnetic waves
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effect of alpha and beta decay on nuclei
radioactive decay occurs in unstable nuclei
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product of alpha decay
helium nucleus
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what happens to the atomic and mass number after alpha decay
atomic number goes down by 2. mass number goes down by 4
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product of beta decay
high speed electron
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what happens when a nucleus decays by beta decay
a neutron turns into a proton
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what is given off by very energetic or excited nuclei
gamma rays
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purpose of a Geiger-Müller tube
to detect the activity of the radioactive sources in Bq. 1 Bq = 1 decay per second
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background radiation
Low-level radiation at the surface of the Earth that comes from cosmic rays and from small amounts of radioactive materials in rocks and the atmosphere.
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Radon is a natural source of radioactivity. What is the name for this radioactivity?
A- background radiation
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There are two sources of alpha radiation in some houses: radon gas in the air and solid americium in a smoke alarm. The alpha particles from radon are a greater risk to health than the alpha particles from americium. Explain why.
1. We can breath in Rn gas which can emit alpha particles into our lungs, they are ionising and can penetrate living cells. 2 We cannot breath in Am, if it emits alpha particles, they will penetrate our skin.
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A nucleus of radon-222 has 86 protons. How many protons are there in a nucleus of radon-220?
A- 86
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A nucleus of radon-222 has 136 neutrons. How many neutrons are therein a nucleus of radon-220?
B- 134
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half-life
the time taken for the mass / number / percentage / activity of radioactive nuclei to have
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Alpha particles are aimed at thin gold foil. Most travelled straight through but some were deflected. All air was removed from the apparatus. Give two reasons why this was necessary.
1 Collisions with air may slow alpha particles too much. 2 Alpha particles will ionise the air particles and stop moving (join)
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Describe the force that caused some alpha particles to deflect
Electrostatic force: positive nucleus repels negative alpha particles
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Experiment shows most alpha particles went straight through foil, some were deflected through a small angle, few were deflected back towards the source. It was concluded that each gold atom has a small, dense positively charged nucleus. Explain why.
1 Most alpha particles went through = mainly empty space - compared to size of atom, nucleus is v. small. Small angle deflection: +alpha particles passes close to +nucleus & is repelled because like charges repel. 3 deflected back:nucleus met head on
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Other cards in this set

Card 2

Front

total number of protons and known as atomic number / proton number

Back

what is Z

Card 3

Front

chemical symbol for the element

Back

Preview of the back of card 3

Card 4

Front

number of neutrons

Back

Preview of the back of card 4

Card 5

Front

a charged atom which has had its number of electrons charged

Back

Preview of the back of card 5
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