Helium is another light element, with a Relative Atomic Mass of just 2, that is, it is 2 times heavier than Hydrogen. This means it is still lighter than air, but this doesn't matter, because it also is a colourless gas at room temperature and pressure.* Helium, like Hydrogen is most commonly found in the air in molecular state and is therefore referred to as He2. Helium is extremely un-reactive and can therefore be found in its molecular state in nature.
Helium has had many uses over the decades, but the most memorable ones have been the humourous way to make your voice high-pitched by inhaling it, and to fill party ballons, so they float to the ceiling.
Helium causes your voice to seem funny when you inhale it because the gas is considerably lighter than air and therefore the molecules are much smaller and there are greater gaps between them. This helps the passage of the vibrations of the vocal cords, speeding them up and therefore raising the pitch. Some heavier-than-air gases can be inhaled to lower the pitch of the voice, but they will be mentioned in due time.
The current uses of Helium are as a replacement for Hydrogen in air ships (see The Elements: Hydrogen for more information), and, for the same reason, to fill party balloons.
Helium is most abundantly found in party baloons, but in nature, most of it can be found in the air. The air is a special mixture of gases consisting mostly of Nitrogen and Oxygen (more on those later in the series), and a small amount of most other elements.
Coming up next week (give or take a few days) we have the ever loved element: Lithium!
*Room tempreature is considered as being 37 degrees centigrade and room pressure is considered to be 1 Atmos.