By: Trevor Brucato

Discovery of the Element

• Date Discovered:– August 18, 1868

• Founder of Helium Discovery:– French astronomer, Pierre Janssen:

Unknown yellow spectral line in the light of a solar eclipse

– English astronomer, Norman Lockyer: Helium was separately identified as a new element later that year

http://kryolab.fysik.lu.se/dokument/e_helium.html

Characteristics of Helium

• Atomic #: 2

• Atomic Weight: 4.00260 g/mol

• Protons: 2

• Electrons: 2

• Neutrons: 2

• Charge: 0

• 1st ionization energy (Kj/ mol): 2372

• Electronegativity: None

• Melting Point (K): 1

• Boiling Point (K): 4

• Density (g/cm3): 0.000179

• Atomic Radius (pm): 32

http://en.wikipedia.org/wiki/Helium

Source of Helium• How is Helium Purified?

– Helium is removed from natural gas, which all natural gas contains traces of helium. The fusion of hydrogen into the helium gives energy for the hydrogen bomb. The helium from most of the alpha particles has been trapped deep within the earth, not far from the top of the mantle. Helium diffuses very rapidly, so it can be expected to have been mobile in the crust.

– This gas served to develop the methods for separation of helium devised by the Bureau of Mines. There are two general ways to do this:

• To adsorb all but the helium on cooled activated charcoal, and the other is to liquefy the gas and separate the helium by fractional distillation.

• As in the case of hydrogen, air diffused into the helium and had to be removed to preserve the lifting power, but, not to avoid an explosive mixture.

• What ore can Helium be found in?– Helium can be found in Uranium.

• Where can Uranium be found?–

http://www.corrosionsource.com/handbook/periodic/2.htm

Uses of Helium Present-day Uses:

• Scientists use it in physics labs• Weather Balloons• Airships• Party Balloons (Inhaling Helium)• Filling balloons (blimps) as it is a much safer gas

than hydrogen • Widely used as an inert gas shield for arc welding

in countries where helium is cheaper than argon • Protective gas in growing silicon and germanium

crystals, and in titanium and zirconium production

• Cooling medium for nuclear reactors • A mixture of 80% helium and 20% oxygen is used

as an artificial atmosphere for divers and others working under pressure

• Cryogenic applications • As a gas for supersonic wind tunnels • A protective gas for semiconductor materials • Pressurizing liquid fuel rockets

Future Uses:• A lifting gas in devices to lift

heavy loads for construction

• Minor medical uses

• Uses in lasers

Past Uses:• Science Experiments

http://youtube.com/watch?v=-qr7OMa7OiI

http://www.webelements.com/webelements/scholar/elements/helium/uses.html

Bohr-Rutherford Diagram• 2 Protons • 2 Electrons (In first orbital)

http://www.lionden.com/chemistry_models.html

More on Helium - - Properties of Helium:

• Second lightest element (always rises)

• It is chemically inert, having no tendency to combine with other elements

• The boiling point of helium is closer to absolute zero than that of any other element, so liquid helium can provide the lowest operating temperatures of any refrigerant

• Non-flammable

- - Helium Balloon Experiment

http://video.google.com/videoplay?docid=1651943932055129679&q=helium+(he)&hl=en