The chemical element with atomic number 2 in the periodic table is helium. Helium has 2 protons in its nucleus, which gives it an atomic number of 2. It is a noble gas and is represented by the symbol "He" in the periodic table. Helium is the second lightest element and is known for its low density and non-reactive nature. It is widely used in various applications, such as cryogenics, filling balloons, and as a shielding gas in welding.