Frantz,+Noel

[|HELIUM] = =  [|History] A French astronomer, Pierre-Jules-César Janssen (1824-1907), first obtained evidence for the existence of helium during the solar eclipse of 1868 in India when he detected a new yellow line (587.49 nm) in the solar spectrum very close to the yellow sodium D-line. It was not possible to produce this line in the laboratory. Sir Norman Lockyer (1836-1920), an English astronomer, recognised that no known element at that time gave this line and named the element helium for the sun. For many years helium was regarded as an element that might exist on the sun although it was unknown on the Earth. Spectroscopists at the time doubted the results concerning helium. [|Discovery] A French astronomer first obtained evidence for the existence of helium during the solar eclipse of 1868 in India when he detected a new yellow line (587.49 nm) in the solar spectrum very close to the yellow sodium D-line. It was not possible to produce this line in the laboratory. Sir Norman Lockyer (1836-1920), an English astronomer, recognised that no known element at that time gave this line and named the element helium for the sun. For many years helium was regarded as an element that might exist on the sun although it was unknown on the Earth. About Helium **Symbo**l: He **Boiling Point**: -268.93 degrees C **Melting Point**: N/A **Density**: .1785 g/l **Protons**: 2 **Neutrons**: 2 **Electons**: 2 **Atomic Number**: 2 **Atomic Mass**: 4.00 **Orbital Notation**: 1s 2  **Valence Electrons**: 2 **Chemical Properties**: color, reactions **Physical Properties**: Boiling piont, Temperature **Minerals**: occluded helium and this can be liberated by heating **Compounds**: halides, oxides, hydrides **Two Chemical Reactions**: pressurizing liquid fuel for rockets, protective gas for semiconductor materials **Industrial Uses**: help NASA's shuttle go to space **Commercial Uses**: filling party balloons **Cost/Value**: $5.2 per gram **Produced**: Helium is used in cryogenics, its the largest single use absorbing a quarter of the production
 * When**: 1895 **Who**: Pierre-Jules-César Janssen, Sir William Ramsay, Cleve, Langley, ans Sir Norman Lockyer **How**:

[|Bohr Model Of Helium] Unusual Facts >First found in the sun  >not found in the human body   >lowest melting and boiling points   >Important to anyone who needs a MRI scan to help diagnose their injury   >[|Helium is the name for the Greek God of the sun, Helios]

Sources [|http://www.periodictable.com]   [|http://webelements.com]   [|http://www.chemicool.com]   [|http://buzzle.com]   [|http://www.bml.gov]