How can I solve nuclear equations?
Nuclear equations can be solved quite simply: let's do one example of alpha decay and one of beta decay.
First, a quick revision of radioactive decay:
During alpha decay, an alpha particle is emitted from the nucleus —- it is the equivalent of a helium atom (i.e. it has a mass of 4 and an atomic number of 2). So, let's take the following question:
Polonium-210 is a radioisotope that decays by alpha-emission. Write a balanced nuclear equation for the alpha decay of polonium-210.
In symbols, the equation becomes
The sums of the superscripts and of the subscripts must be the same on each side of the equation.
Take 4 away from the mass number (210-4 = 206)
Take 2 away from the atomic number (84-2 = 82). Lead is element number 82.
So, the equation is
Now let's try one for beta decay — remember that, in beta decay, a neutron turns into a proton and emits an electron from the nucleus (we call this a beta particle)
Write a balanced nuclear equation for the beta decay of cerium-144)
In nuclear equations, we write an electron as
Add one to the atomic number (58+1 = 59).
Don't change the mass number
Praseodymium is element 59
The answer is Pr-144.
Here's a fission reaction.
A nucleus of uranium-235 absorbs a neutron and splits in a chain reaction to form lanthanum-145, another product, and three neutrons. What is the other product?
We write a neutron as
Sum of superscripts on left = 236. Sum of superscripts on right = 148. So
Sum of subscripts on left = 92. Sum of subscripts on right = 57. So
The nuclear equation is