Helium is one of six noble gases that include argon, neon, krypton, xenon, and radon. Noble gases are a group of elements which share a certain set of properties – they are odorless, have no color, they are monatomic (they are gases in which atoms are not bound), are nonflammable, and have virtually no chemical reactivity.
Properties of Helium
Helium is considerably less dense than the atmosphere, which is why it is used to inflate balloons and such when you want those balloons to float in mid-air. Because it is less dense than the surrounding air, exhaling helium raises the pitch of the voice because of the change to the frequency of the sound waves made by the larynx. It is the second least dense element at .1785 g/cm ³ weighing only slightly more than the least dense element hydrogen at .0899 g/cm ³ at 0 degrees Celsius. [“Density for all the elements” Periodictable.com]
Considering that oxygen comprises 47% of earth’s mass, it would seem that it should be right at the top of the list for abundance of elements in the universe. At number three, it is. But, it does not compare to the abundance of hydrogen and helium. Hydrogen is the most abundant element comprising ¾ the mass of the universe. Nearly the whole of the remaining ¼ is made up of Helium. [“What Is the Most Abundant Element?” General Chemistry Online]
Because noble gases have weak interatomic forces, they are characterized by low melting and boiling points. Helium boasts the lowest of all the elements at 272 degrees Celsius and -269 degrees Celsius respectively. [Propertiesof MatterElement Card: Helium” Properties of Matter]
“Density for all the elements in the Periodic Table.” The Photographic Periodic Table of the Elements. N.p., n.d. Web. 7 Jan. 2013. http://periodictable.com/Properties/A/Density.al.html
“What Is the Most Abundant Element?” General Chemistry Online: FAQ: The Periodic Table:. N.p., n.d. Web. 07 Jan. 2013.