can nuclear chemists convert elements into unstable ones? If so how?
Nuclear physicists do it usually, in very small quantities.
Some element has to be bombarded with either neutrons, or protons, and these have to be captured by each nucleus. As you can imagine, it is not easy, some what like swatting flies with a pencil in the dark.
Most transmutations (look that word up)are done in nuclear reactors, where the neutron density is very, very high.
By adding enough neutrons, the nucleus splits into other elements,usually unstable, and they split, etc
OR by adding neutrons, some of the neutrons decay to proton and beta particle, to make another element, and it is usually unstable, and decays.