氢(hydrogen)
一种轻的化学元素，化学符号H，原子序数1。一种无色、无臭、无味的可燃性气体物质，氢原子很活泼，可以彼此结合成对，形成分子式为H2的双原子氢分子。其原子含有一个质子和一个电子；其同位素氘和氚分别多出一和二个中子。虽然氢在地球上的丰度只占第九位，但占宇宙中所有物质质量的75%。氢过去用於填充飞船；无味的氦已取代它。氢气主要用於氨、乙醇、苯胺和甲醇的合成；石油燃料的脱硫；也是一种还原剂（参阅reduction）和补充减少中的大气；制备氯化氢（参阅hydrochloric acid）和溴化氢；还用於有机化合物的氢化。液态氢（沸点-252.8℃）用於实验室以产生极低的温度，用於气泡室中，和用作火箭燃料。燃烧氢和氧可产生水。大多数酸尤其是在水溶液中的酸，其各种性质都是因存在氢离子（H+，亦可产生水合氢离子H3O+，因此任何水的环境都可发现氢离子）而产生的。亦请参阅hydride、hydrocarbon。
English version：
hydrogen
Lightest chemical element, chemical symbol H, atomic number 1. A colorless, odorless, tasteless, flammable gas, it occurs as the diatomic molecule H2. Its atom consists of one proton (the nucleus) and one electron; the isotopes deuterium and tritium have an additional one and two neutrons, respectively. Though only the ninth most abundant element on earth, it represents about 75% of all matter in the universe. Hydrogen was formerly used to fill airships; nonflammable helium has replaced it. It is used to synthesize ammonia, ethanol, aniline, and methanol; to treat petroleum fuels; as a reducing agent (see reduction) and to supply a reducing atmosphere; to make hydrogen chloride (see hydrochloric acid) and hydrogen bromide; and in hydrogenation. Liquid hydrogen (boiling point −487°F, or −252.8°C) is used in the laboratory to produce extremely low temperatures, in bubble chambers, and as a rocket fuel. Combustion of hydrogen with oxygen produces water. The properties of most acids, especially in water solutions, arise from the hydrogen ion (H+, also referred to as the hydronium ion, H3O+, the form in which H+ is found in a water environment) See also hydride, hydrocarbon.