How do you complete the following alpha decay reaction?
The general notation of a nuclide (
In alpha decay the nucleus emits a particle that contains 2 protons and 2 neutrons, which is similar to the nucleus of helium. So a notation for the nuclide (
Now you can complete the equation given in the example:
The last step is finding the nuclide that has 90 protons and 142 neutrons in a table of nuclides. This appears to be Thorium (
This makes the equation complete: