Radioactive materials Flashcards
What did the Rutherford-Geiger-Marsden alpha particle scattering
experiment find?
It found that a gold atom was mainly empty space, as most of the alpha particles they fired at the atom went straight through, but in the center was a small but massively dense nucleus that was positively charged, as some alpha particles were repelled
How are protons and neutrons held together in the nucleus?
Strong nuclear force holds the nucleus together, it balances the repulsive electrostatic force between the protons
How does nuclear fusion work?
If hydrogen nuclei can be brought close enough together they will experience a strong nuclear force and fuse to become helium nuclei, releasing their energy
How can we calculate the energy released during nuclear fusion and fission?
Einstein’s equation of E = mc^2 (E is the energy produced, m is the mass lost and c is the speed of light in a vaccum)
What does the number of protons atom tell us?
The number of protons in a nucleus determines the element and its chemical properties.
What are isotopes?
The number of neutrons in the nucleus of an element can vary for the same element, these are different isotopes.
Different isotopes of an element have a different number of neutrons but always the same number of protons
What are the three types of ionising radiation, what is each?
The three types are alpha, beta and gamma.
Alpha particles are helium nuclei, they have 2 protons and 2 neutrons.
Beta particles are identical to electrons.
Gamma rays are very high frequency electromagnetic waves
What are the penetrating and ionising properties of each type of ionising radiation.
Alpha particles are the least penetrating but the most ionising.
Beta particles aren’t as ionising as alpha, but are more penetrating.
Gamma rays are very penetrating but weakly ionising.
What happens over time to the radioactivity of a source?
It decreases as more and more radiation is emitted
What is the mass number and atomic number of alpha particles/ helium nuclei?
The mass number is 4 and the atomic number 2
What is the mass number and atomic number of beta particles/ electrons?
The mass number is 0 and the atomic number is -1
What is half life? How long can it be?
The time it takes for half the nuclei in a sample to decay, this is different for each element and can vary from seconds to millions of years
