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What happens when a Beta Particle is Emitted from a Nucleus?

After a radioactive nucleus has emitted a beta particle, the
mass number stays the same and the atomic number goes up by 1.

A neutron in the nucleus has changed into a proton plus an electron.
The proton stays inside the nucleus but
the electron is emitted as a beta particle.
The change in the atomic number produces a different element.

Nuclear Equations for Beta Particle Emitters.

In the nuclear equation below,
carbon-14 becomes nitrogen-14 by emitting a beta particle.

The nuclear equation is balanced because the mass number
on the left of the arrow is equal to the sum of the mass numbers
on the right of the arrow,  14 = 14 + 0.
Similarly for the atomic numbers6 = 7 - 1.

Using a Nuclear Equation to find which Particle is Emitted.

Some nuclei can decay by emitting either an
alpha particle or a
beta particle. An example is bismuth
where 1/3 of the atoms emit an alpha particle
and 2/3 of the atoms emit a
beta
particle.

You can work out which particle is emitted by balancing the equation.

In the nuclear equation above, the mass number of the
unknown particle is 212 - 208 = 4.
The atomic number of the unknown particle is 83 - 81 = 2.
The particle that has a mass number 4 and atomic number 2
is an
alpha particle.

What Element would be formed if Bismuth emitted a B
eta Particle?

Answer - it would have a mass number 212 and atomic number 84.
This element is polonium.

This form of polonium and the form shown on page 6 are isotopes.

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