chemistry
posted by Shay on .
Radon222 undergoes alpha decay.what is the nuclear equation

First number just before Rn is atomic number; number following symbol is mass number.
86Rn222 ==> 2He4 + nXm
We we need to evaluate for n and m. To do that we remember that the atomic numbers must add on both sides and the mass numbers must add up on both sides.
86 = 2+n; therefore, n = 84
222 = 4 + m; therefore, m = 218
Now we look on the periodic table and find element number 84. That is Po; therefore, element X is Po so the equation in full is
86Rn222 = 2He4 + 84Po218