在未谈到重水(heavy water)之先,我们应先介绍一下同位元素(isotopes)。同位元素为原子序相同,而原子重量相异之元素,如氢有三种同位素,原子量各为1,2,3。通常原子量为一者,称第一氢,原子量为二者,称第二氢或重氢。水之分子式为H_2O,即由二个氢原子与一个氧原子化合而成,但上面已经谈过,氢有三种同位 Before we talk about heavy water, let’s talk about isotopes. Elements with the same atomic order, and atomic weight of different elements, such as hydrogen has three isotopes, atomic weight of 1,2,3. Usually one of the atomic weight, said the first hydrogen, atomic weight of both, said the second hydrogen or heavy hydrogen. The molecular formula for water is H_2O, which consists of two hydrogen atoms combined with one oxygen atom, but as we have already discussed, there are three hydrogen isotopes