Writing Alpha and Beta Decay Equations

Writing Alpha and Beta Decay Equations

Alpha Decay

Alpha decay can most simply be described like this:

1) The nucleus of an atom splits into two parts.

2) One of these parts (the alpha particle) goes zooming off into space.

3) The nucleus left behind has its atomic number reduced by 2 and its mass number reduced by 4 (that is, by 2 protons and 2 neutrons).

Here is a typical alpha decay:

Ra-222 ---> He-4 + Rn-218 Notice several things about it:

1) The atom on the left side is the one that splits into two pieces.

2) One of the two atoms on the right is ALWAYS an alpha particle.

3) The other atom on the right ALWAYS goes down by two in the atomic number and four in the mass number.

Here's another example:

Po-208 ----> He-4 + Pb-204
Check it and compare the three points to the example. Keep in mind that this equation shows the left-hand side splitting into the two pieces shown on the right-hand side.

PRACTICE:

1. Lr-256
2. Pa-231
3. Ac-225
ANSWERS:
1. Md-252
2. Ac-227
3. Fr-221
Beta Decay

Beta decay is somewhat more complex than alpha decay is. These points present a simplified view of what beta decay actually is:

1) A neutron inside the nucleus of an atom breaks down, changing into a proton.

2) It emits an electron and an anti-neutrino (more on this later) which go zooming off into space.

3) The atomic number goes UP by one and mass number remains unchanged.

Here is an example of a beta decay equation:

C-14 --> N-14 + e + n Some points to be made about the equation:

1) The nuclide that decays is the one on the left-hand side of the equation.

2) The order of the nuclides on the right-hand side can be in any order.

3) The way it is written above is the usual way.

4) The mass number and atomic number of the antineutrino are zero and the bar above the symbol indicates it is an

anti-particle.

5) The neutrino symbol is the Greek letter "nu." (n)

Here is another example of a beta decay equation:

I-131--> Xe-131 + e + n Notice that all the atomic numbers on both sides ADD UP TO THE SAME VALUE and the same for the mass numbers.

Practice:
1.He-6
2.Na-24
3.Au-201
4.Fe-54
ANSWERS:
1.Li-6 + e + n
2.Mg-24 + e+ n
3.Hg-201 + e + n
4.Co-54 + e + n

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