P6.1 - Radioactive Emissions Flashcards
What is the mass of a proton?
1
What is the mass of an electron?
1/2000
what is the mass of a neutron?
1
what is the relative charge of a neutron?
0
what is the relative charge of an electron?
-1
what is the relative charge of a proton?
+1
What does the charge on the nucleus of an atom depend on?
The number of protons in it
What are isotopes?
Atoms of an element with different numbers of neutrons
what does the ‘12’ refer to in the atom:
carbon-12
the total number of subatomic particles in the nucleus
how do you work out the number of neutrons in an atom?
subtract the amount of protons (or atomic number) from the relative atomic mass
What do unstable nuclei emit?
Radiation
What do you call materials that emit radiation?
radioactive
What is the symbol for an alpha particle?
α
what is the symbol of a beta particle
β
what is the symbol for a gamma particle?
γ
How is radiation detected?
Using a Geiger counter.
device clicks when radiation enters it
what is each click in a Geiger-Miller tube?
a tiny current produced when radiation ionises atoms of gas inside the tube
List three types of radiation in order from least penetrating to most penetrating.
alpha
beta
gamma
What material stops alpha particles?
a few sheets of paper
what material stops beta particles?
a few mm of aluminium
what material stops gamma particles?
a few cm of lead (or m of concrete)
what kind of radiation is emitted by radioactive materials?
and what does it mean?
ionising radiation,
means that the radiation can remove electrons from atoms or give electrons to atoms to produce ions
what is the charge of alpha particles?
+2
what is the charge of beta particles?
-1
what is the charge of gamma particles?
0
why do alpha particles have a shorter range than gamma particles?
because they have high ionising power (transfer more energy to the material that they are travelling through)
What happens in alpha decay?
2 protons and 2 neutrons form an alpha particle and leave the nucleus
Why does alpha decay occur?
since the atom that they are in have an unstable nuclei (too many protons)
Finish off the equation: (alpha decay)
240
Pu —->
94
236 4
U + He
92 2
What happens in beta decay?
When a neutron decays and emits an electron. The neutron itself turns into a proton.
when does gamma ray decay occur?
when a nucleus usually emits an alpha particle or a beta particle (at the same time)
what is a half-life of a radioactive material?
the time it takes for half the unstable nuclei to decay, or for the activity to halve
What is the activity/count rate of a radioactive substance measured in?
Becquerels (Bq)
Radioactive decay is random. Explain what that means
Random means that an event is equally likely in any time interval.
Emission and absorption spectra tell us what about atoms?
Where the electrons are on the atom
How many isotopes will be let after 4 weeks if the original sample had 100 atoms? Half-life of the isotope in question = 7 days
~6 (6.25)
