Bohr Model of the Atom of Helium

**Formula:** He

**Atomic number:** 2

**Relative atomic mass:** 4,003

**Information:** Helium is an inert, colourless, odourless, tasteless and light monoatomic gas. From all known gases, it has the lowest melting and boiling point.

**Use:** It is used to fill balloons and airships. It is loaded (in mixture with other rare gases) into lamps and laser tubes. In liquid state it conducts the electricity very well (superconductivity) and has a very low viscosity (superfluid).

**Appearance:** On Earth it is very rare (noble gas). In the universe, it is after hydrogen the second most abundant element.

Bohr's atomic model assumes that electrons move on stationary circular paths with constant energy.

The Helium atom consists in two positively charged protons, two neutrons and two negatively charged electrons. Protons and neutrons are present in the nucleus; the electrons around them move along circular paths.