Helium

THe Essentials                                                 

               He                   

    Atomic number:  2                                                                                

    Weight:  4.002602 grams

    Electron configuration:  1s²

                                                                    Melting POint:  -269.7 C

                                                                    Boiling Point:  -268.9 C

The History:

The first evidence of helium was found in 1868 by Pierre-Jules Cesar during the solar eclipse.  He found a yellow line (587.49) in the solar spectrum that could not be produced in a lab.  An English astronomer, Sir Norman Lockyer, named the unknown element helium, because many thought that it might exist on the sun but not on the earth.

                    *Helium comes from the Greek word "helios", which means "sun"*

Helium was discovered by in 1895 by Sir William Ramsey when he treated cleveite, a uranium mineral, with mineral acids.  It was identified by Lockyer and Sir William Crookes after Ramsey sent them samples of the gas.

The Characteristics of Helium

Helium is a colorless gas at standard state (298 K).  It is the second most abundant element in the universe.  However, there isn't very much helium on earth because it is so light; most of the helium in the atmosphere is found on the sun and in the hotter stars, where it is used in the production of energy.

*It has the lowest melting point of any element  

*It cannot be solidified; at standard pressure, it will remain liquid even at absolute zero.  However, it can be easily solidified by increasing pressure.                                                

*Helium has an unusually high specific heat (5.19 J/g*C)

*The density of helium vapor @ normal boiling point is very high; in fact, containers filled with helium gas at between 5 and 10 Kelvin should be treated as liquid helium because the pressure greatly increases when the gas is warmed to room temperature.

Uses of Helium                                       

Helium is used in various industries and fields.  Several of these involve inflating large objects:

Balloons:  helium is used extensively for                      

filling balloons (it is much safer than                             

hydrogen is for this purpose).                                     

         <--   This is a helium-filled blimp!                          

Blimps:   Helium blimps are being used for everything from advertising to drug-smuggling detection.  The Navy and Air Force are currently developing blimps to detect low-flying cruise missiles, and NASA is using helium balloons to sample the atmosphere in Antarctica, in order to determine which factors are contributing to the depletion of the ozone layer.                                                  

Other Uses:

Divers use a mixture of helium and oxygen as an artificial atmosphere, with different He/O₂ ratios depending on the depth at which they are operating.

Liquid helium is used in MRI (magnetic resonance imaging).  This technology has eliminated the need for some forms of exploratory surgery, as it is able to accurately diagnose patients. 

$$$ Cost of Helium $$$

In 1986, the United States Bureau of Mines determined the price of Grade A Helium to be

$37.50/1000ft3

BACK

                                                                                                                                                                                                                                                                                   by Lauren Westerfield