How do they create an element that is the same mass as the original one but is a different element by adding neutrons; is that possible?
Table Of Nuclides
The element doesn't change, only its' atomic mass. The number of protons determines what the element is. The number of neutrons determines how the element behaves. Some elements have many different isotopes (different numbers of neutrons), and can behave very differently. Some naturally occurring, some produced/manufactured by nuclear processes, some merely theoretical.
The best example if course is U-235, a very stable isotope of Uranium. Add a neutron and get U-236, a very unstable isotope of Uranium which has a very short half-life and decays (fissions) extremely quickly.
Right at the beginning of the video he says, “You keep adding neutrons until you end to the point where they spontaneously decay and then you end up with something of the same mass but a different element”. As far as I know, it’s the number of Protons that determine the element so how is that possible?