|Atomic Weight||4.002602 g•mol-1|
|Density||(0°C, 101.325 kPa) 0.1786 g/L|
|Melting Point||(at 2.5 MPa) 0.95 K, -272.20 °C, -457.96 °F|
|Boiling Point||4.22 K, -268.93 °C, -452.07°F|
Helium is called a noble gas, because it does not regularly mix with other chemicals and form new compounds. It has the lowest boiling point of all the elements. It is the second most common element in the universe, after hydrogen, and has no color or semll. However, helium has a blue-ish, neon color when being burnt with fire. Helium does no usually react with any thing. Astronomers found helium in 1868. They found that it was in the Sun before it was found on Earth. Because of where it was found, its name comes from the Greek word for Sun, helios.
It is used to fill balloons and airships because it is lighter than air, and does not burn or react, meaning it is normally safe for using it in that way. It is also used in some kinds of light bulbs. People also breathe it in to make their voices sound higher than they normally do as a joke, but this can be dangerous if they breathe in too much, since it can kill them because they are not breathing normal air. Breathing too much helium can also cause long-term effects to vocal cords.
It can be created through the process of nuclear fusion in the Sun. During this process, four hydrogen atoms are fused together to form one helium atom.