If Sr 90 undergoes beta decay, then what is the resulting element and atomic weight of the product after the beta decay has occurred?

Rb 90, same atomic weight.

is a type of radiation where a proton in the starting element changes into a neutron. A byproduct of this is a beta particle, or an electron. There is no change in in this decay, just .

To set up this type of decay, we want to write down the correct notation for Strontium-90:

##""_38^90 Sr##

The top number is the mass number, and the bottom is the atomic number.

To set up the actual beta decay formula, we write our starting element on the left, followed by an arrow and the resulting element and particle on the right:

##""_38^90 Sr rarr ""_37^90 Rb + beta^-##

So, in this formula, we see that when ##""_38^90 Sr## undergoes beta decay, it produces ##""_37^90 Rb## and a beta particle, which represents an electron.