Inert Gas of the Week

Helium is my inert gas of the week. It is abbreviated He, it has 2 electrons, and it's mass is 4.002602. This is really weird -- it's melting point is <-272.2 C and it's boiling point is -268.93 C. It has the lowest melting point of any element! It's used in cryogenic research because it's boiling point is close to absolute zero. It is the only liquid that cannot be solidified by lowering the temperature -- it remains liquid to absolute zero at ordinary pressure but will solidify by increasing the pressure. How bizarre, huh? It is used to cool nuclear reactors, in MRI's, and of course, my favorite, in balloons, among other things. It is named for the sun, from the Greek "helios". Some person named Janssen first obtained evidence of helium during a solar eclipse in 1868, when he detected a new line in the solar spectrum. Except for Hydrogen, it is the most abundant element in the Universe!! It has been detected spectroscopically in great abundance, especially in the hotter stars. (I like the hot stars.) Here on Earth, it is extracted from natural gas, mostly here in the US. The cost of helium fell from $2500 per cubic foot in 1915 to 1.5 cents per cubic foot in 1940. Wow, did anyone have a lot invested in the helium market back then??