Period 1 element lithium and fluorine (appearing twice), or left floating above the other elements and not assigned to any group in the periodic table. Helium is almost always placed above neon (which is in the p-block) in the periodic table as a noble gas, although it is occasionally placed above beryllium due to their similar electron configuration. Hydrogen (H) is the chemical element with atomic number 1. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly flammable diatomic gas with the molecular formula H. With an atomic mass of 1.00794 amu, hydrogen is the lightest element. Hydrogen is
Period 1 element zero have on matter, such as with superconductivity. Helium is the second lightest element and is the second most abundant in the observable universe. Most helium was formed during the Big Bang, but new helium is being created as a result of the nuclear fusion of hydrogen in stars. On Earth, helium is relatively rare and is created by the natural decay of some radioactive elements because the alpha particles that are emitted consist of helium nuclei. This radiogenic helium is trapped with natural gas in concentrations of up to seven percent by volume, from which it is extracted commercially