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在高一化学第五章中,有关原子量有四个容易混淆的概念。它们是:质量数、同位素的原子量、元素的原子量、元素的近似平均原子量。这四个量都是以_6~(12)C的一个原子绝对质量的1/12作为标准,比较而得的相对质量。但它们的意义是各不相同的。 质量数和同位素的原子量是指具体原子(核素)而言,而元素的近似平均原子量和元素的原子量则是指元素来说的;另一方面,质量数和元素的近似平均原子量是近似值,而同位素的原子量和元素的原子量是精确值。例如,氧元素有三种同位素:_8~(16)O、_8~(17)O、_8~(18)O。它们的质量数分另,1为16、17、18;同位索原子量分别为15.994915、16.999133、17.99916;氧元素的近似平均原子量和原子量分别为16和15.9994。
In the fifth chapter of Highschool of Chemistry, there are four easily confused concepts about atomic weight. They are: mass number, atomic weight of the isotope, atomic weight of the element, and approximate atomic weight of the element. The four quantities are based on the relative mass of one atomic absolute mass of _6 ~ (12) C as the standard. But their meaning is different. Mass and isotope atomic weight refers to a specific atom (nuclide) terms, and elements of the approximate average atomic weight and the atomic weight of the element refers to the element; on the other hand, the approximate average atomic weight of the mass and elements are approximate, The atomic weight of the isotope and the atomic weight of the element are exact values. For example, oxygen has three isotopes: _8 ~ (16) O, _8 ~ (17) O, _8 ~ (18) O. Their mass numbers are divided by 1, 16, 17, and 18; isotope atomic weights are 15.994915, 16.999133, and 17.99916, respectively; and the approximate average atomic weights and atomic weights of oxygen elements are 16 and 15.9994, respectively.