Protons and the atomic number

Rocky asks, "Can the number of protons in an atom ever be different than what is given on the periodic table?"


An excellent question, Rocky, which gets at what makes an element that element. The atomic number gives the number of protons in a single atom of that element (which also gives the usual number of electrons in that element to balance out the total charge). An element must have that number of protons, or else it simply is not that element anymore. If an element gains (fusion) or loses (fission) protons, it becomes a different element altogether. This is what happens, for example, in the fusion process in the sun. Two atoms of hydrogen (essentially just single protons as the electrons are stripped away at such high temperatures) fuse into a single atomic nucleus and give off energy in the process. Left over is an atom with two protons. In other words, helium.


So, Rocky, while an element can have different numbers of neutrons (isotopes) or electron (ions), they can only have the number of protons given on the periodic table. Thank you for your question!