Helium | Name | Helium | | Symbol | He | | Atomic Number | 2 | | Atomic Mass | 4.002602 atomic mass unit | | Number of Protons | 2 | | Number of Neutrons | 2 | | Number of Electrons | 2 | | Melting Point | -272° C | | Boiling Point | -268.6° C | | Density | 0.1785 grams per cubic centimeter | | Normal Phase | Gas | | Family | Noble Gas | | Period | 1 | | Cost | $37.50 per 1000 cubic feet | | Origin of Name | From the Greek word helios, meaning sun | | Date and Place of Discovery | 1868 in France and in England 1895 in England | | Discovered by | - Pierre Janssen in France first noticed a bright yellow line during an eclipse (1868)
- Norman Lockyer in England noticed a yellow line in the solar spectrum (1868)
- Sir William Ramsay discovered helium on earth (1895)
| | Common Compounds | - No stable compounds are formed with helium.
| | Interesting facts | - It is created as a result of radioactive decay.
- It is nonflammable.
- Its the most abundant element known in the universe after hydrogen.
| | Common Uses | Main filling for blimps (airships) Used to fill balloons Detects leaks in sealed containers Gas shield for arc welding Growing silicon and germanium crystals for protective shields Production of protective shields using titanium and zirconium As a cooling factor in nuclear reactors Artificial atmosphere created with 20% oxygen Cryogenic applications (low temperature) Pressurizing liquid fuel rockets | Photo Courtesy of About.com Cary Academy Chemical Elements Wikipedia | | Helium Atomic Structure | Elements by Name | Elements by Number | Home | |
