Which element has the atomic number 1?
Hydrogen. Notice that all isotopes of hydrogen have the same atomic number, but some of them have been given different names (deuterium, tritium). 1) “Hydrogen (pronounced /ˈhaɪdrədʒən/) is the chemical element with atomic number 1. It is represented by the symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H2. With an atomic weight of 1.00794, hydrogen is the lightest element.” “The most common isotope of hydrogen is protium with a single proton and no neutrons. In ionic compounds it can take a positive charge (a cation composed of a bare proton) or a negative charge (an anion known as a hydride).” Source and further information: http://en.wikipedia.org/wiki/Atomic_number_1 2) “Hydrogen (H) (Standard atomic mass: 1.00794(7) u) has three naturally occurring isotopes, denoted 1H, 2H, and 3H. Other, highly unstable nuclei (4H to 7H) have been synthesized in the laboratory but
