Helium is a chemical element with the atomic number of 2 it is a colorless, odorless and tasteless gas. It is often used to fill party balloons as it is good at making things go up due to it being lighter than air. Helium is hard to find on earth due to it being made deep underground out of the natural radioactive decay of elements such as uranium and thorium. Helium also changes your voice into a higher pitch due to its low density, This causes the sound to travel over twice as fast through helium than regular air.