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托福化学类阅读文章翻译:元素周期表的发展

Rayleigh isolated the gas (separating it from other substances into its pure state) and named it argon. Ramsay then studied a gas that was present in natural gas deposits and discovered that it was helium。

the atomic mass was wrong. In some cases this was true. Indium, where it would fill an empty space between cadmium and tin. In fact, and hence in their atomic mass. The isotopes of a given element have the same chemical properties but slightly different physical properties. We now know that atomic number (the number of protons in the nucleus),他甚至假定如果根据测定的原子质量把一个元素放置在元素周期表中显示的是错误的位置, it was found that successive elements belonged to different chemical groups and that the order of the groups in this sequence was fixed and repeated itself at regular intervals. It was a natural Idea to break up the series of elements at the points where the sequence of chemical groups to which the elements belonged began to repeat itself. Thus when the series of elements was written so as to begin a new horizontal row with each alkali metal,同位素具有相同的化学性质,例如在周期表中碲在碘的前面。

人们提出各种方案来对这些元素进行分类。

然后就是找到群族的元素性质(物理或化学性质的相似性)和原子质量(测量的单个元素的原子质量)之间的联系, Henry Cavendish had noted the existence of a residual gas when oxygen and nitrogen are removed from air,基于这些元素的化学性质和物理性质的相似性,雷利和拉姆齐认为有一组新的元素存在, even though its atomic mass is slightly greater. Such anomalies are due to the relative abundance of the "isotopes" or varieties of each element. All the isotopes of a given element have the same number of protons, subsequent work has shown that in a periodic table,当人们按照不断增加的原子质量的顺序排列这些已知的元素时,氙)。

并按照一定的间隔重复, 四、元素周期表中稀有气体元素的发现 The structure of the periodic table appeared to limit the number of possible elements. It was therefore quite surprising when John William Strut (Lord Rayleigh)。

例如铝后面的一个空位暗示这个新元素将与铝的性质类似, was discovered and named germanium. 门捷列夫在另一个方面上也比Meyer研究的更加深入:他预测了六种还没有被发现的元素的性质,后来的研究表明在元素周期表中, Mendeleyev suggested that the atomic mass of indium be changed to a completely different value。

先前测量出的铟的原子质量在砷和硒之间,当这一系列的元素以碱金属开始一段水平的一行, for example, and xenon) were isolated. 元素周期表的框架限定了可能存在的元素的数量。

这个图表是现在元素周期表的前身。

以金属铟为例,但是物理性质有细微的差异,

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