Helium - WikipediaHelium is a chemical element with symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements. After hydrogen, helium is the second lightest and second most abundant element.الهيليوم نيون تتركز,Encyclopedia of Laser Physics and Technology - Helium-neon .Helium-neon lasers are gas lasers based on a helium-neon mixture. They often, but not always emit red light.
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