Transcript Radioactive Decay Series Worksheet

Radioactive Decay Series Worksheet
Init 5/11/2012 by Daniel R. Barnes based on a years-old worksheet
mass number =
# of protons + # of neutrons
a
238
92
U
atomic number =
# of protons
Radioactive Decay Series Worksheet
4
???
???
2
alpha particle
238
92
He
??
a
U
An alpha particle has a mass number of 4
and an atomic number of two.
Because of its atomic number, an alpha
particle is, essentially, a helium nucleus.
Radioactive Decay Series Worksheet
4
2
He
a
238
92
U
234
???
???
90
Th
??
Alpha decay make a nucleus’ mass
number go down by four.
Alpha decay also makes a nucleus’ atomic
number go town by two.
Radioactive Decay Series Worksheet
4
2
He
a
238
92
U
0
???
???
-1
234
90
Th
An beta particle has a mass number of 0
and an atomic number of negative one.
A beta particle is, essentially, an electron
that gets shot out of a radioactive nucleus
at very high speed.
e
??
b beta particle
Radioactive Decay Series Worksheet
4
2
He
a
238
92
U
234
90
Th
0
-1
e
b
234
???
91
???
During beta decay, a neutron in the nucleus of
the atom splits into a proton and an electron.
The proton remains in the nucleus, causing its
atomic number to increase by one, while the
electron is ejected as a beta particle.
Pa
??
Radioactive Decay Series Worksheet
b
a
238
92
U
234
90
Th
b
234
91
Pa
It looks like the uranium atom has turned back
into uranium again, but is it exactly the way it
was at the beginning?
Almost. The atomic number is the same, but
the mass number has changed.
The atom is now the same element it used to
be, but it is a different isotope of uranium.
234
92
U
Radioactive Decay Series Worksheet
b
a
238
92
U
234
90
Th
b
234
91
Pa
234
92
U
SUMMARY:
Alpha decay causes mass number to go down
by four and atomic number to go down by two.
Beta decay causes mass number to
stay the same and atomic number to
go up by one.
a
230
90 Th
A gamma particle might come out during alpha or beta decay, but
when it does, it does not affect the mass number or the atomic
number.