Radioactive decay Flashcards
what is a stable nucleus?
a stable nucleus is when a nucleus has a certain amount of neutrons for the amount of protons it has.
as the number of protons increases, more neutrons are needed to keep the nucleus stable. For example lead, lead-206 has 82 protons and has 124 neutrons.
how can a nucleus become more stable?
unstable isotopes decay\ into other elements and give out radiation as they try to become more stable
what are the types of nuclear decay?
Alpha , Beta ,Gamma
what is ionising radiation?
Ionising radiation is radiation that knocks electrons off atoms, creating positive ions
what is the ionising power of a a radiation?
The ionising power is how easily radiation can knock electrons off atoms, creating positive ions.
when is an Alpha particle emitted? And what happens to the nucleus when it is?
An alpha particle is emitted when the nucleus has too few neutrons, emitting a package of two protons and two neutrons called an Alpha particle.
Alpha decay causes the mass number of the nucleus( protons + neutrons ) to decrease by 4, And the mass number to decrease by 2
describe the properties of The Alpha particle
1) Alpha particles do not penetrate far into materials
2) can only travel few cm in air
3) can be stopped by a sheet of paper
4) they are strongly ionising cause of their size.
what is a betta particle?
A beta particle is a neutron that has been turned into a proton and a fast-moving electron. it has a relative mass number and atomic number of zero and as the beta particle is an electron it is written as B-1
it is basically an electron but not from the atoms shells but from its nucleus as a neutron turned to1 a proto 2 a electron
what are the properties of a Beta particle?
1) it has medium/low ionising power
2) medium penetrating
3) need 5 mm of aluminium to be stopped
4) travel 50 cm in air
what are gamma ray?
gamma rays are electromagnetic waves emitted only with an alpha or beta particle this is so hat the nucleus can get rid of some energy
They casue no change in the atomic or mass number
what are the properties of gamma rays?
1) they have low ionising power(cant nock off electrons as they don’t collide with any atoms but ass through materials)
2) can penetrate a lot so travel long distances in air and need thick sheets of lead and (need concrete to stop it)this is because they have no mass or charge
how can radioactive decay be detected?
Geiger-Muller tube
The radiations ionise the gas inside and the resulting charged particles move across the chamber and get counted as charges rather like an ammeter.
what is half life?
Half-life is the time it takes for half of the unstable nuclei in a isotope to decay or for the activity of the sample to halve or for the count rate to halve. Count-rate is the number of decays recorded each second by a detector, such as the Geiger-Muller tube
how can we measure a decay process?
as the decay process is random
