If we remove one electron from a neutral hydrogen atom, it will become a hydrogen ion with a positive charge. The atomic number (Z) of an atom corresponds to the number of protons in its nucleus, so removing an electron does not change the number of protons. Therefore, the new atomic number (Z) will still be 1, indicating that it is still a hydrogen atom.
However, the mass number (A) of an atom corresponds to the total number of protons and neutrons in its nucleus. Since a hydrogen atom usually has no neutrons, removing an electron does not change the mass number. Therefore, the new mass number (A) will still be approximately 1.
The hydrogen ion, formed by removing an electron, is often denoted as H+ to indicate its positive charge. It is still called hydrogen because the defining characteristic of an element is the number of protons in its nucleus, which remains unchanged. Although the hydrogen ion has a different electrical charge than a neutral hydrogen atom, it is still considered a form of hydrogen due to its atomic number (Z) of 1.