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Physics Topic 3
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- 1What is each energy level?A different distance away from the nucleus
- 2How can an inner electron move up to a higher energy level?If it absorbs EM radiation, with the right amount of energy
- 3What happens when an inner electron moves up?It moves to an empty or partially filled shell and is said to be ‘excited’
The electron will then quickly fall back to its original energy level, and in doing so will emit the same amount of energy it absorbed. The energy is carried away by EM radiation - 4What process ionises atoms?Nuclear Radiation
- 5What is ionising radiation?Any radiation that can knock electrons from atoms
- 6What do unstable isotopes tend to do?Decay into other elements and give out radiation as they try to become more stable. This process is called radioactive decay
- 7Examples of ionising radiationAlpha
Beta
Gamma
Neutrons - 8What is alpha radiation?When an alpha particle is emitted from the nucleus. An alpha particle is two neutrons and two protons (like a helium nucleus)
- 9What causes alpha particles to strongly ionise?Their size
- 10What is a beta-minus particle?A fast moving electron released by the nucleus. They have virtually no mass and a relative charge of -1
- 11What is a beta-plus particle?A fast moving positron. The positron is the antiparticle of the electron. This just means it has exactly the same mass as the electron, but a positive charge +1
- 12What do both beta-minus and beta-plus particles do?They are both moderately ionising
- 13What do beta-minus particles have?A range in air of a few metres and are absorbed by a sheet of aluminium (around 5mm thick)
- 14What do positrons have?A smaller range in air. Because when they hit an electron the two destroy each other and produce gamma rays - this is called annihilation and it’s used in PET scanning
- 15What are Gamma Rays?EM waves with a short wavelength.
They are released by the nucleus that carry away this energy - 16What are nuclear equations?A way of showing radioactive decay by using element symbols
- 17When a nucleus emits an alpha particle what happens?It loses two protons and two neutrons.
So the mass number decreases by 4 and the atomic number decreases by 2 - 18During beta-minus decay, how does a neutron change?The neutron changes into a proton and an electron so:
The mass number doesn’t change and the atomic number increases by 1 - 19During beta-plus decay, how does a proton change?It changes into a neutron and a positron so:
The mass number doesn’t change and the atomic number decreases by 1 - 20When a nucleus emits a neutron during neutron emission what happens?The mass number decreases by 1 and the atomic number stays the same
- 21What are gamma rays are way of getting rid of?They get rid of excess energy from an atom. The nucleus goes from an excited state to a more stable state by emitting a gamma ray. The mass and atomic number stay the same after a gamma ray has been emitted
- 22What happens each time a radioactive nucleus decays?One more radioactive nucleus disappears
- 23As the unstable nuclei all steadily disappear what happens?The activity as a whole will decrease
- 24What is a half-life?The average time taken for the number of radioactive nuclei in an isotope to halve
- 25What is a short half-life?The activity falls quickly, because the nuclei are very unstable and rapidly decay.
- 26What is a long half-life?The activity falls more slowly because most of the nuclei don’t decay for a long time
- 27What is background radiation?The low-level radiation that’s around us all the time
- 28What does background radiation come from?Radioactivity of naturally occurring unstable isotopes which are all around us
Radiation from space, which is known as cosmic rays
Radiation due to human activity eg nuclear waste - 29What is the amount of radiation you’re exposed to called?Absorbed radiation dose
- 30What does your radiation depend on?Depending on where you live or if you have a job that involves radiation
- 31What is exposure to radiation called?Irradiation. It simply means objects are exposed to it
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- GCSE Physics Fichas sobre Physics Topic 3 , creado por Harry Smith el 25/11/2018.
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- Harry Smith
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