I assume that you mean Helium ... one of the Noble Gases. It is the second lightest Element, Hydrogen is the first. Being a noble gas, it does not burn so it is used in balloons. The noble gases do not readily combine with other elements to form other compounds ... they just 'stand alone.' A balloon filled with hydrogen can and does easily explode, but one filled with helium will not
An element. It is the gas that makes balloons float and makes your voice sound squeaky.