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Slide 1

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Additional Physics
Topic 5…read more

Slide 2

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Elements can be described by their atomic number and mass number
· Elements can be described by looking at their atomic number and the
mass number. You must be thinking what is this about?
· This is the periodic table (you must have heard of it, started by
Mendeleev and expanded on by other scientists).
Mass number-
The number of
neutrons and Symbol- The
protons in the shorthand
atom form of the
name of the
element e.g.
number- The
number of
protons in the
atom…read more

Slide 3

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· Isotopes are atoms with the same mass number but a
different atomic number. For example carbon-12 and
Carbon-14. Most atoms have different isotopes however,
some of these isotopes are stable(Carbon-12) while some are
radioactive (Carbon-14). Radioactive isotopes decay in to a
new element and spit out high energy radioactive particles
and waves. This is where radioactivity comes from.
· Radioactivity is based on entirely random activity. For
example you can never predict when an isotope will decay or
how an atom will decay. When the process of decaying does
take place the unstable nuclei will spit out alpha, beta or
gamma radiation…read more

Slide 4

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Alpha, Beta and Gamma
Alpha particles-
· Consist of two neutrons and two protons
· they are very strongly ionising
· don't penetrate (scientific way of saying travel)
far in to materials
· Can be stopped by a thin sheet of paper
· Have a very strong positive charge
· They attract the electrons in an atom and cause
them to be pulled out of it's orbit, of the atom.
This works as, opposite charges attract (+ and ­
or ­ and +).
· Can be stopped by a thin sheet of paper or
anything equivalent such as skin.…read more

Slide 5

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Alpha, Beta and Gamma
Beta Particles:-
· Are fast moving electrons
· Have a negative charge
· Are moderately ionising
· Penetrate into materials moderately
· They repel with the electrons in a atom causing it
to be pushed out of orbit, of the atom. This works
because like charges repel (- and ­ or + and +).
· They can be stopped by a thin sheet of aluminum
or any thin sheet of metal…read more

Slide 6

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Alpha, Beta and Gamma
Gamma waves:-
· They are a form of radiation from the
electromagnetic spectrum
· They are weakly ionising
· Penetrate far in to materials
· They transfer energy to the electrons. Once when
the electrons get enough energy they can break
free, out of orbit.
· They can be stopped by a thick sheet of lead or
concrete.…read more

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