By: Alyssa Parsons

 Helium has the lowest melting point and boiling point of the elements, so it only exists as a gas except under extreme conditions.  Helium is the second-most abundant element in the universe, though it is much less common on Earth.  Evidence of helium's existence came from observation of a yellow spectral line from the sun.  Helium is colorless, odorless, tasteless, non-toxic, and inert.  Helium is the second-least reactive noble gas (after neon)

 Pierre Janssen discovered the helium atom!  Pierre Janssen was a French astronomer who discovered helium in He was observing a solar eclipse in India when he noticed the yellow spectral emission lines of the element.

 DFgg&edufilter=FwNIMIqIDIQYAexPZDE7XA DFgg&edufilter=FwNIMIqIDIQYAexPZDE7XA

 This section lists some binary compounds with halogens (known as halides), oxygen (known as oxides), hydrogen (known as hydrides), and some other compounds of helium. For each compound, a formal oxidation number for helium is given, but the usefulness of this number is limited for p-block elements in particular.

Helium FormulaHe Molecular Weight (lb/mol)4.00 Critical Temp. (°F) Critical Pressure (psia)33.0 Boiling Point (°F) Melting Point (°F)-- Specific 70°F 1 atm (ft3/lb)96.65 Specific Gravity0.138 Specific 70°F (Btu/lbmol-°F)4.97

 Helium is used as a cooling medium for the Large Hadron Collider (LHC), and the superconducting magnets in MRI scanners and NMR spectrometers. It is also used to keep satellite instruments cool and was used to cool the liquid oxygen and hydrogen that powered the Apollo space vehicles.  Because of its low density helium is often used to fill decorative balloons, weather balloons and airships. Hydrogen was once used to fill balloons but it is dangerously reactive.  A mixture of 80% helium and 20% oxygen is used as an artificial atmosphere for deep-sea divers  Helium-neon gas lasers are used to scan barcodes in supermarket checkouts.

 Balloons  The Sun  Compressed Air Tanks  Lasers  Coolants

 Helium is one of the so-called noble gases. Helium gas is an unreactive, colorless, and odorless monoatomic gas. Helium is available in pressurized tanks. Helium is the second most abundant element in the universe after hydrogen.