Balancing Nuclear Equations
Beta Emission

The second type of radioactive emission is beta particle emission. A beta particle(β) is a fast moving electron. We use the symbol 0-1e. Note that the isotopic mass for the electron is considered to be zero because it is much, much less than that of a proton or neutron. While it does have mass, it is just too small to worry about. The electron's atomic number is "-1" because of the electron's negative charge.

For example, Carbon-14 is used to date ancient objects like mummies, and it decays by beta emission.

14 14 0
C N + e
6 7 -1

Again, the top and bottom numbers are equal on both sides of the equation ([14 = 14 + 0] and [6 = 7 + -1]).