the central region of an atom which consists of protons and neutrons. It contains the most mass in an atom
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proton
subatomic particle, mass is 1 and charge is +1
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neutron
subatomic particle, mass is 1 and charge is 0. It isn’t stable and can decay to make an electron or proton
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electron
subatomic particle, mass is 0.0005 (effectively 0) and charge is -1
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the charge of the nucleus of an atom
it depends on the number of protons in the atom an is unique to particular elements
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the charge on nucleus is +1
hydrogen
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the charge on nucleus is +79
gold
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why nuclei of different elements have different masses
Atoms of an element all contain the same number of protons but can also contain different numbers of neutrons- this changes the mass while not changing the charge.
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isotopes
atoms with the same number of protons but a different number of isotopes. They are written in the format ‘c-12’ . the -12 refers to the total number subatomic particles in the nucleus.
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deuterium
a hydrogen isotope ( hydrogen-2)
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stable atoms
atoms that don’t decay or breakdown
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unstable atoms
atoms that decay and emit radiation which can be made up of particles or waves. They are radioactive.
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radiation
the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles which cause ionization. there are 3 types.
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alpha radiation
A type of particle radiation which is the nucleus of a helium atom. The symbol is α and the equation symbol is ⁴₂He. It has short range, large mass and high ionising power.
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beta radiation
A type of particle radiation which is a fast moving electron. The symbol is β and the equation symbol is ⁰₋₁e. It has a medium range, small mass and medium ionising power
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gamma radiation
A type of wave which is an electromagnetic wave. The symbol is γ and there is no equation symbol. Its has no mass, no charge and a long range.
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neutron radiation
A type of particle radiation which is a particle in the nucleus. The symbol is n and the equation symbol is ¹₀n
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geiger counter
a device that clicks when radiation enters it. Each click is a tiny current produced when radiation ionises atoms of the gas inside the tube.
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penetrating power
how much material radiation can pass through. (Highest-lowest) gamma, beta alpha
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few sheets of a paper, or skin
it can stop alpha radiation.
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few mm of aluminium
it can stop beta radiation
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few cm of lead or m of concrete
it can stop gamma radiation mostly (some still can pass through)
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ionising radiation
radiation emitted by radioactive materials, it can remove electrons from atoms to create positively charged ions.
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alpha decay
a nuclear decay process where an unstable nucleus changes to another element by shooting out a particle composed of two protons and two neutrons. This ejected particle is known as an alpha particle and is simply a helium nucleus.
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beta decay
a nuclear decay process where a neutron decays into an electron and is emitted as a beta particle. The number of neutrons goes down by one and the number of protons goes up by one.
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gamma decay
it is emitted usually alongside an alpha and beta decay. The atomic number and mass stays the same when this happens
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neutron emission
when some nuclei decay they produce nuclei with large numbers of neutrons,
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activity/ count rate
radiation emitted per second (measured on a Geiger counter). It is measured in becquerels (Bq)
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becquerels (Bq)
A unit of measurement for radiation. One becquerels is one count or wave per second. You can measure lower activities in counts per minute
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Half-life
The time it takes for the activity to half. It is also the same as the time for the nuclei of half the atoms to decay. the probability for any 1 nucleus to decay in 1 second is fixed which means decay is random and half life is fixed.
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Irradiation
When an object is exposed to radiation. This can be used to sterilise food and medical instruments and chemotherapy
Studied by 15 people
