chapter 7 Flashcards
what do you use to detect radioactivity
Geiger-muller tube
what are the 3 types of radiation
alpha beta gamma
what is alpha radiation made up of
positively charged particles
what is the nucleus made up of
protons and neutrons
what makes an atom radioactive
unstable nucleus
how does an atom get more radioactieve
emitt more alpha beta or gamma
what is alpha stopped by
paper
does beta go through paper
yes
which is the most penetrating form of radiation
gamma
what experiment did rutherford carry out
he directed a narrow beam of alpha particles at thin metal foil, some of the particles re bounded back from teh foil, he proved that this happens because each atom has a positively charged nucleus at its centre. He went on to prove that the nucleus contains protons and neutrons
who discovered that alpha and beta were made out of differnet particles
ernest rutherford
when investigating how thin metal foil scatters a beam of alpha particles why did they do it in a vacumm chamber
prevent air molecules absoribing the alpha
in rutherfords experiment how many alpha particles were deflected by more then 90 degreess
1 in 10 000
why did the alpha paricles bounce back
because they were posative and so was the protons it was hitting in the nucleus which repelled them
what did rutherford conclude from his experiment
there is a posativly charged nucles in the centre of every atom that is :
much smaller then the atom as most particles pass through
where the most mass is located
what changes in alpha decay
number of protons and neutrons
what changes in beta decay
number of protons
what is an isotope
same mumber of protons but differnt number of neutrons
what happens to an atom in alpha decay
its mass number goes down by 4 and its atomic number goes down by 2
what happens to a atom emitting beta
the mass number stays the same and the atomic number goes up by1
what happens to a atom in gamma emission
nothing
what is alphas range in air and what is it absorbed by
5cm range in air and is absorbed by thin sheets of paper
what is betas range in air and what is it absorbed by
1 m range in air and is absorbed by 2-3mm of lead
what is gammas range in air and what is it absorbed by
unlimited range in air and is absorbed by 1m of concrete
what is ionisation
when the radiation from a radioactibe substance can knock the electrons out of atoms
what is it called when an object is exposed to ionising radiation
irradiated
what is radioactive cotammnination
the unwanted presence of materials containing radioactive atoms in other materials
which is the most dangerous radiation in the body and why
alpha - the most ionising
what is the activity of a radioactive source
the number of unstable atoms in the source that decay per second
what is the unit for activity
Bq
what is half life
the time it takes for activity to half
how do radioactive tracers work
They are used to trace the flow of a substance through an organ. The tracer contains a radioactive isotope that emits gamma radiation. Before the test the patient would drink water with a small amount of radiation, a detector is then placed against each kidney, the substance would flow in and out of a normal kidney so the detector would go up then down , for a blocked kidney the reading would go up and stay up.
what happens in fission
the nuclues of an atom is struck by a neutron, causing the nucleus to split into 2 smaller fragment nuclei and release neutrons
what does fission release
2 or 3 neutrons , energy in the form of gamma radiation + kinetic energy
what does water do in a fission reacter
acts as a moderator as it slows down the fission neutrons
how does fusion work
2 small nuclei are fused together to form a single larger nucleus
