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
Extended periodic table (detailed cells) Extended periodic table (detailed cells) This is a large version of the extended periodic table of the chemical elements. For the natural isotopic composition of each element it shows "name", "atomic number", "symbol", "standard atomic weight" (or atomic weight) and a link to the element's isotopes. It also has, by keyed markings, a notification of "occurrence", "state of matter" and "metallic character". It is named "extended" because it shows elements that are theoretical only (in period 8), and "large" means that the table might exceed page width. The presentation is wide which means that there are no table parts separated