Question

What would the nuclear equation be for the beta- decay of strontium- 90?

Answer 1

Hint: To solve this kind of question we need to have the knowledge of nuclear beta- decay. Beta- decay is of two types Beta minus decay and Beta plus decay. Strontium- 90 undergoes beta minus decay. In beta minus decay the parent particle is fused into a daughter element, single electron and the energy.

Complete answer:
The question given asks us to find the nuclear equation for the beta- decay of the Strontium- 90. To start with the study of the beta- decay. Beta- decay refers to a type of radioactive decay in which a beta particle, which is a fast energetic electron or positron, is emitted from an atomic nucleus which is transformed into the original nuclei and to an isobar of the nuclide.
Strontium-90, ${}^{\text{90}}\text{Sr}$, undergoes beta minus decay, so our goal here will be to use the emission of a beta particle to figure out the resulting nuclide. A beta particle, ${}_{-1}^0\beta$ , is simply a high-speed electron. When a radioactive nuclide undergoes beta minus decay, a neutron located inside its nucleus is being converted into a proton.
More specifically, the atomic number will increase by $1$ . As per the periodic table we see that the atomic number of the Strontium is $38$.
This means that the daughter nuclide will have an atomic number of $38+1=39$
Another quick look in the periodic table will reveal that the daughter nuclide is yttrium-90, 90Y.
You can thus write out the nuclear equation that describes the beta minus decay of strontium-90 like this:
${}_{38}^{90}Sr\to {}_{39}^{90}Y+{}_{-1}^0\beta +{\overline{v}}_e$

Note: In all the kinds of the reaction taking place mass and charge is always conserved. In this situation we also the mass of Strontium is being conserved.
$90=90+0$
Similarly, in conservation the charge we can write:
$38=39+(-1)$