| 释义 |
hy·dro·gen
\ˈhīdrə̇jə̇n, -rēj-\ noun
(-s)
Etymology: French hydrogène, from hydr- (water) + -gène -gen; from the fact that water is generated by its combustion
: a nonmetallic univalent element that is the simplest and lightest of the elements, that is normally a colorless odorless highly flammable diatomic gas, that occurs in the free state only sparsely on the earth and in its atmosphere though abundantly in the sun, many stars, and nebulae, and in combination as a constituent of innumerable compounds from many of which it can be readily prepared (as from water by electrolysis, from natural gas or other hydrocarbons by reaction with steam or by pyrolysis, from acids by reaction with active metals), and that is used chiefly in synthesis (as of ammonia and methanol), in reducing or hydrogenating a variety of compounds (as in hardening oils to fats), as a mixture with oxygen or as atomic hydrogen in producing very high temperatures (as in welding), as liquid hydrogen for rocket fuel and in producing very low temperatures, and in filling balloons — symbol H; see deuterium, element table, ortho-hydrogen, para-hydrogen, synthesis gas, tritium |