Question

Can you write the nuclear decay equation for the beta decay of iodine-131?

Answer 1

The equation is `""_53^131"I" → ""_54^131"Xe" + color(white)(l)_text(-1)^0"e"`

Explanation:

β decay is a process in which a nucleus emits an electron.

The nuclear symbol for a β particle is `color(white)(l)_text(-1)^0"e"`.

In any nuclear equation, the sum of the subscripts (atomic numbers, `"Z"`) and the sum of the superscripts (atomic masses, `"M"`) must be equal on each side of the equation.

For the β decay of iodine 131, we have

`""_53^131"I" → color(white)(l)_text(Z)^"M""X" + color(white)(l)_text(-1)^0"e"`

Hence

`131 = "M" + 0`, so `"M" = 131`
`53 = "Z - 1"`, so `"Z" = 53 + 1 = 54`

The element `"X"` with `"Z = 54"` is `"Xe"`.

So the equation is

`""_53^131"I" → ""_54^131"Xe" + color(white)(l)_text(-1)^0"e"`

Note that in β decay, the product has the same mass number but an atomic number that has increased by 1.

Here's a video on writing β decay equations.