Radioactivity Flashcards
What is the average radius of an atom
1 × 10⁻¹⁰ metres
OR
0.1 nm
What is a positron?
A sub-atomic particle, not usually found in most atoms. It has a charge of +1 and a negligble mass.
How did Rutherford’s tin foil experiment contribute to our understanding of the atomic model?
He fired a beam of alpha particles at thin metal foils. Most of the alpha particles passed through the foil, but some were deflected back out. This suggests that most of an atom is empty space. This also suggests that there must be a positively charged sub-atomic particle, that causes some of the alpha beam particles to deflect, as positive repels from positive.
What happens to the electrons in an atom when radiation is a) absorbed and b) emmited
Absorbed - the elecrons “move to a higher energy level” further away from the nucleus
Emitted - the electrons “drop to a lower energy level” closer to the nucleus
Atomic number and atomic mass are also known as…
AND definitions
Proton Number - Z, (atomic number):
- the number of protons in an element. E.g, Neon will always have 10 Protons, so it’s atomic number is 10.
Nucleon number - A, (atomic mass):
- the number of protons and neutrons in an element.
- the number of neutrons in an element is not always the same. This is why isotopes form.
How do ions form/what is an ion?
An is an atom that has become charged. This occurs by gaining more electrons than it has protons (becomes negative) and by loosing more electrons than it has protons (becomes positive)
What is a nuclide?
A specific nucleus that contains a certain number of protons and neutrons.
What is ionisation?
When an atom becomes an ion/charged particle through gaining or loosing electrons.
Define and exlplain the four types of radioactive decay.
Alpha Decay
- produces helium/alpha particles
- 2 protons and 2 neutrons
- inverse proportion/fish sign
Gamma Decay
- produced by gamma rays
- excited nucleus releases energy
- 0 mass and 0 charge.
- not a particle, just energy.
Beta-minus Decay
- a neutron decays to form a proton and an electron
- the electron is ejected from the nucleus at a high speed
- mass = negligible, charge = -1
Beta-plus Decay
- a neutron decays to form a proton and a positron
- the positron is ejected from the nucleus at a high speed
- mass = negligible, charge = +1
What are the 3 ways of detecting ionising radiation and how do they work?
- photographic film (A bright spot appears wherever the ionising radiation hits the film)
- geiger-müller tube (a tube of low-pressure gases which ionises atoms in the gas. It knocks electrons out of the atoms. It conducts electricity and completes an electric circuit, which produces a clicking noise)
- cloud chamber (Ionising radiation enters the air and leaves a trail of ionised air molecules/particles. The alcohol vapour condenses on the ionised air molecules)
How does nuclear fission work?
When the large nucleus of an atom splits into other smaller nuclei. (Typically uranium and platonium.)
- An atom collides with a large neutron. This neutron is then absorbed, which creates an excited or unstable nucleus.
- In order to become stable again, the nucleus splits into many fragments, some of which are neutrons.
- These neutrons collide with other fragments to split them even further. This creates a large amount of energy.
- This energy boils water, which is used to spin a turbine within a generator. This produces electricity.
What is an explosion?
A sudden release of pressure, gas, light and heat, produced by chemicals.
Name the 6 sources of background radiation in descending order:
- Radon Gas
- Cosmic Rays
- Ground and Buildings
- Food and Drink
- Nuclear Power Plants
- Nuclear Tests and Accidents
Name the radioactive radiation sources from most ionising to least ionising:
Alpha (most ionising)
Beta (moderately ionising)
Gamma (least ionising)
Name the radioactive radiation sources from most to least penetrating power:
Gamma (most penetrating)
Beta (moderately penetrating)
Alpha (least penetrating)
