Nuclear Notes
The nucleus of the atom is held together by the _________________
_______________. Normally protons would try to _______________ each other.
The strong force can hold small nuclei together that have a ratio of _____ neutron
to _____ proton. In more massive nuclei the ratio is _____ neutrons to _____
protons. Isotopes of elements tend to be _______________ because they
_______________ these ratios.
When the strong force is not enough to hold an atom together the nucleus will fall
apart, we call this _______________ _______________.
When an element goes through nuclear decay it can become a new element, we
call this _______________.
Remember that we can denote isotopes in the following ways.
This is important because even when a nucleus undergoes decay __________ must
be conserved (stay the same). Charge must also be _______________.
Alpha decay
This is an _________ particle. It is made up of 2 __________ and 2
__________, it has a charge of __________. This is also known as a
_______________ _______________. When a nucleus undergoes alpha decay it
emits one of these particles.
Symbol
Mass
Charge
Nuclear reactions can be written as equations. The one below would be for the
reaction pictured above.
Alpha particles are a very _______________ form of _______________. An alpha
particle can be stopped by a sheet of _________________. Alpha decay can cause
limited damage to living tissues.
Beta decay
Beta decay is caused by the _______________ of an ________________ from the
nucleus of the atom. A neutron breaks down into a _______________ and an
_______________. The proton stays in the nucleus and the electron is ejected at
high speed.
Symbol
Mass
Charge
The nuclear equation for beta decay for the above reaction can be written as
follows.
Beta particles are ejected at a higher velocity than alpha particles. Beta particles
can pass through paper but will be stopped by ______________ __________.
Because of its greater penetrating power beta decay can be more damaging to
living tissue than alpha decay.
Gamma decay
_______________ decay is the most _______________ type of radiation. It is the
emission of _______________ waves from the nucleus. _______________ rays
are the _______________ of the electromagnetic waves. These are the most
________________ and the most ________________ of the electromagnetic
waves. Gamma rays are so penetrating that it takes blocks of _______________ or
sheets of _______________ to stop them.
Symbol
Charge
Comparison of the three types of decay
Half life
http://www.pbslearningmedia.org/asset/nvhe_vid_decay/
The half- life of an isotope is the ______________ it takes for _______________ of
the amount of the isotope to ______________.
Carbon – 14
half-life
amount left
Nitrogen - 14
Radiometric dating
Scientists know the half-life of many radioactive isotopes. They can use this
information to date ancient materials. _______________ can be used to measure
the age of once living materials. _______________ can be used to rocks. The ratio
of the starting isotope to ending isotope calculated, from this the age of the
artifact can be determined.
Nuclear fission
_______________ _______________ is the _______________ of a large atom into
smaller atoms. A _____________ is fired at a large atom like U-236. This causes
the large atom to undergo _______________, splitting the atom into two smaller
nuclei and some extra neutrons.
During nuclear fission some of the __________ of the starting materials is
converted to ___________. There is more mass in the reactants than there is in
the products, this missing __________ is converted into tremendous amounts of
___________. Einstein’s equation __________________ shows the relationship
between _________ and ____________.
Chain reaction
Nuclear fission can be used to start a ________________ _________________.
The _______________ that are released from the first _______________ reaction
then move toward other large nuclei and collide with them causing other
________________ reactions to take place. This will continue until there are no
more suitably _______________ enough nuclei to react with.
For a _______________ ________________ to occur there must be a sufficient
number of large nuclei for the _______________ to react with. There must be
enough material/mass. This is known as _________________
_________________. If there is not enough ___________ then a chain reaction
will not occur.
Nuclear Fusion
_______________ __________________ is a nuclear reaction the takes
_______________ atoms and __________ them together to create one
_______________ atom. Fusion only takes place at ________________
temperatures. The heat causes the atoms to move at high velocity. The high
velocity overcomes the nuclei’s natural repulsion to each other allowing them to
come close enough to _______________ together.
The only place that nuclear fusion takes place naturally is in _______________.