That is not how nuclear bombs are made.
This will happen naturally if the element is radioactive and can be done artificially by means of neutron bombardment in a nuclear reactor or in the heart of a star.
It would become a different element. It could become radioactive.
Helium is chemically inert and does not combine with any other element (including thallium).
It would become an atom of a different element. This can only happen during radioactive decay, nuclear fusion, or nuclear fission.
By losing protons. Atomic number determines what kind of element it is. ---------------------------- This can only happen if the nucleus changes its number of protons because the nucleus is unstable and undergoes radioactive decay. As it changes it will emit some form of radiation
When the number of neutrons changes, the atomic mass will change.
In order for an atom of an element that is not radioactive to become radioactive, the isotope has to change. This can happen as a result of neutron capture. Neutron capture can simply change the isotope of an atom, as when cobalt-59, which is not radioactive, captures a neutron to become cobalt-60, which is radioactive. Neutron capture can also result in immediate radioactive decay of the atom struck, even if it is not radioactive. For example helium-3 can capture a neutron to produce two atoms of hydrogen, one of hydrogen-3 and one of hydrogen-1.
by radioactive material fell in the air
By losing protons. Atomic number determines what kind of element it is. ---------------------------- This can only happen if the nucleus changes its number of protons because the nucleus is unstable and undergoes radioactive decay. As it changes it will emit some form of radiation
We would not be eating fish
The decay of radioactive substances follows a decay chain that will sooner or later result in the appearance of a stable isotope of lead. There is an exception for the atoms of a few substances that have undergone decay by spontaneous fission.
Become radioactive and die..