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24 Cards in this Set
- Front
- Back
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What is at the centre of an atom?
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A nucleaus
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What is is the nucleus?
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protons and neutrons
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What makes up most of the mass of an atom?
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The nucleus.
BUT IT IS TINY AND TAKES UP VIRTUALLY NO SPACE |
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What surrounds an atom
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Electrons. They whiz around the outside. Their paths take up a lot of space.
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What takes up most of the space in an atom
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The electrons. Their paths take up a lot of space, giving the overall size, but it's mostly empty space.
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What is the atomic number of an atom?
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The number of protons in the nucleus.
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What is the mass number of an atom?
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The number of protons and neutrons in nucleus
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What are isotopes?
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Atoms with different numbers of neutrons.
They have the same atomic number, but different mass number. |
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What is the difference between carbon-14 and carbon-12?
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They are isotopes of carbon. carbon-14 has two extra neutrons than carbon-12.
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What makes an element?
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The number of protons or its atomic number.
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How many stable isotopes does an element usually have?
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One or two. carbon-12 is stable. carbon-14 is unstable and decays (breaks down) and emits radiation.
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What is the smallest mass in an atom
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The electron. carries a single negative charge -1.
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How much heavier is a proton than electron?
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2000 times. carries single positive charge +1
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How much mass does a neutron have compared to a proton?
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About the same. NO CHARGE THOUGH
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Show the structure of a carbon-12 and carbon-14 atom
A = atomic mass X = chemical symbol for element Z = atomic number |
12 and 14
C C 6 6 |
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What is radioactive decay?
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When the nuclei of UNSTABLE isotopes break down and emit radiation.
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What sort of process is radioactive decay?
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The nuclei of unstable isotopes, like carbon-14, break down at RANDOM.
1000 unstable nuclei will not decay at same time and you can't predict or do anything to make it happen. |
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Does anything natural influence decay?
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NO!! It's completely unaffected by physical conditions like temp or chemical bonding
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What happens when a nucleus decays?
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It spits out one or more of three types of radiation: alpha, beta, gamma.
IN THE PROCESS THE NUCLEUS OFTEN CHANGES TO A NEW ELEMENT |
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What sort of background radiation do we have?
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substances on Earth - food, rocks, soil
cosmic rays - radiation from space - solar flares living things - radiation from plants eaten etc. human activity - nuclear waste etc. (though tiny compared to others) |
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What decides what an element is
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Number of protons
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What decides what an isotope is?
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Number of neutrons
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What sort of isotopes decay
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unstable ones
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If there are 6 protons in an atom, how many electrons are there?
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6. number of electrons same as protons.
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