P6 Key Facts Flashcards
What is an isotope?
atoms with the same number of protons but a different number of neutrons in the nucleus (the same element)
What happens if an isotope is unstable?
the nucleus is unstable which means the atom decays (breaks down) to make them selves more stable and then emit radiation as a result of this
what happens when an atom decays?
either alpha beta or gamma radiation is released and the atom often changes into a new element
what happens when ionising radiation transfers enough energy?
the atom or molecule breaks into ions (ionisation) - these ions then go on to take part in other chemical reactions
How can alpha particles be described?
relatively big, heavy and fairly slow moving meaning that they don’t penetrate far into materials (stopped quickly)
They are also only released by a very heavy nuclei (uranium)
what is an alpha particle?
It is a helium nucleus made up of 2 protons and 2 neutrons (meaning its top number is 4)
What happens in alpha decay?
because the mass of an Alpha particle is 4 and the charge is 2+, the top number is reduced by 4 and the bottom number is reduced by 2 as well as an Alpha/He atom being emitted
how can Beta particles be described?
They are quite fast and small - they penetrate moderately into materials before they are stopped
They are released by nuclei that have too many neutrons
What is a Beta particle?
It is identical to an electron (e), it has virtually no mass and a charge of -1
What happens during Beta decay?
a neutron in the nucleus turns into a proton so the element changes (top number stays the same, bottom number decrease by 1)
What is gamma radiation?
a type of electromagnetic wave that has no mass
When are gamma rays emitted?
after spitting out an alpha or beta particle, the nucleus needs to get rid of some extra energy so it emits a gamma ray
It can penetrate a long way into materials but since gamma is just energy, it can’t change the element of the nucleus that emits it
what is a half-life
the time taken for half of the radioactive nuclei now present to decay (this is the only way we can measure activity as it never reaches zero)
What does a short half life mean?
the activity falls quickly because lots of the nucleus decay in a short period of time
what is the strong force?
an attractive force much greater than the repulsive electrostatic force between the protons, this force holds the nucleus together
