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Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.
Hydrogen and helium are the most commonly used lift gases. Although helium is twice as heavy as (diatomic) hydrogen, they are both significantly lighter than air. The lifting power in air of hydrogen and helium can be calculated using the theory of buoyancy as follows: Thus helium is almost twice as dense as hydrogen.
Helium-3 (3 He [1] [2] see also helion) is a light, ... The decay of tritium into helium-3 reduces the explosive power of the fusion warhead, so periodically the ...
The inert gas system is used to prevent the atmosphere in cargo tanks or bunkers from coming into the explosive range. [9] Inert gases keep the oxygen content of the tank atmosphere below 5% (on crude carriers, less for product carriers and gas tankers), thus making any air/hydrocarbon gas mixture in the tank too rich (too high a fuel to oxygen ...
Helium is inert - it does not react with other substances or combust - and its atomic number is 2, making it the second lightest element after hydrogen. Rockets need to achieve specific speeds and ...
Helium is the smallest and the lightest noble gas and one of the most unreactive elements, so it was commonly considered that helium compounds cannot exist at all, or at least under normal conditions. [1] Helium's first ionization energy of 24.57 eV is the highest of any element. [2]
Precautions are necessary when using hydrox, since mixtures containing more than four percent of oxygen in hydrogen are explosive if ignited. Hydrogen is the lightest gas (one quarter the atomic mass of helium or one half the molecular mass of helium) but still has a slight narcotic potential and may cause hydrogen narcosis.
Helium is the only element cold enough to keep MRI machines cool enough to function. Without it, doctors lose a valuable imaging tool. The world is running out of helium. Helium is the only ...