P6: Radioactivity Flashcards
What are the three particles found in an atom?
Electron, Proton, Neutron
Which two particles are found in the nucleus?
Protons and Neutrons
What do we mean by ‘unstable’ atom?
Unstable atoms have more neutrons than protons
Oxygen contains 8 protons. What is the difference between the oxygen-16 and oxygen-18 isotopes?
Oxygen-18 has more neutrons than Oxygen-16
Is the rate of radioactive decay affected by chemical processes?
Unstable atoms decay at random and you cnat predict when it will happen it is completely unaffected by physical conditions.
What is Alpha Radiation?
Alpha particles are relatively big and heavy and fairly slow-moving. A alpha particle is a helium nucleus, with a mass of 4 and charge of 2+
What is Beta Radiation?
Beta particles move quite fast and they are quite small, during beta decay a neutron turns into a proton and emits a electron.
What is Gamma Radiation?
Gamma usually happens after decay of an alpha or beta particle. It gets rid of extra energy. They have no mass and are a electromagnetic wave. It doesnt change the nucleus of the element that emits it.
What substance can be used to block alpha radiation?
A sheet of paper
What substance can be used to block beta radiation?
Thin aluminium
What substance can be used to block gamma radiation?
Thick lead
DEFINE: Half life
A half life is the time taken for half of the radioactive nuclei present to decay.
What did the Rutherford-Geiger-Marsden experiment reveal about the nucleus?
It showed that the nucleus is postive, teh scatter showed that it had to be postively charged otherwise alpha particles wouldnt be repelled by the nucleus and scatter
Why don’t postively charged particles in the nucleus fly apart from each other?
The nucleus doesnt fly apart because its held together by an attractive force much greater than the repulsive electrostatic force beween the protons called the strong force.
What idea is summed up in the equation E=MC2
It sums up the idea that mass is a form of energy and can be converted into other forms of energy.
What type of particle keeps a fission chain reaction going?
Neutrons
What units are doses of radiation measured in? What two things does dose take into account?
Sieverts or more usually millisieverts. It takes into account the type and amount of radiation you’ve been exposed to.
Give four categories of people who are at a higher than normal risk of exposure to radiation.
Miners, some medical staffs, nuclear researchers, airline staff, uranium miners/processors.
Give three sources of background radiation.
Natural radioactive elements in the air, soil, living things, rocks.
Space - cosmic rays
Human activity - nuclear explosions/ nuclear waste
