化学专业英语

1、Beginning in the late seventeenth century with the work of Robert Boyle, who proposed the presently accepted concept of an element, numerous investigations produced a considerable knowledge of the properties of elements and their compounds.早在17义耳就开始了这项工作，他提出了现在公认的元素概念，大量的研究使我们对元素极其化合物的性质有了相当的了解。

In modern form, the law states that the properties of the elements are periodic functions of their atomic numbers. In other words, when the elements are listed in order of increasing atomic number, elements having closely similar properties will fall at definite intervals along the list.用现代的话说，这个规律叙述了元素的性质是它们的原子序数的周期性函数。换句话说，当元素按照原子序数逐渐递增的顺序列表（排列时），性质非常接近的元素将占据表格中具有一定间隔的位置.Thus it is possible to arrange the list of elements in tabular form with elements having similar properties placed in vertical columns.于是，将具有类似性质的元素排成纵列，从而把元素排成表格形式是可能的。

The groups headed by the members of the two 8-element periods are designated as main group elements, and the members of the other groups are called transition or inner transition elements.。由两个8元素周期中的元素开头的族被指定为主族元素，其它族的元素叫过度元素或内过度元素.

However, as is characteristic of most transition elements, they form ions having other charges as well.但是，象许多过度元素所具有的特点一样，它们也形成具有其它电荷的离子。

They form such a variety of compounds that it is not practical at this point to present any examples as being typical of the behavior of the respective groups.它们形成了各种不同的化合物，在这一点上我们甚至不能举出任何能表现各族元素典型变化的例子。

The periodicity of chemical behavior is illustrated by the fact that, excluding the first period, each period begins with a very reactive metal. Successive elements along the period show decreasing metallic character, eventually becoming nonmetals, and finally, in group VIIA, a very reactive nonmetal is found. Each period ends with a member of the noble gas family.元素化学性质的周期性可以由以下事实说明：除了第一周期之外，其它每一周期都从非常活泼的金属开始。同一周期随着原子序数的增加，元素的金属性减弱，最终成为非金属，最后，在第七主族，出现了活泼的非金属元素。每一周期都以惰性气体家族成员结束。

2、As molecular weight increases, we encounter a liquid (Br2) and a so1id (I2) whose vapor pressures a1so indicate small intermolecular forces.随着分子量的增加，我们就会遇到一种液体Br2和一种固体I2，它们的蒸气压也表明它们的分子间作用力较小。

The difference arises because of the lower stability of π-bonds formed from p orbitals of the third and higher main energy levels as opposed to the second main energy level.差别的出现是由于与第二主能级相反，第三和更高主能级的p-轨道形成的π-键稳定性较低。

The structure of amorphous sulfur consists of large-coiled helices with eight sulfur atoms to each turn of the helix; the overall nature of amorphous sulfur is described as rubbery because it stretches much like ordinary rubber. In a few hours the amorphous sulfur reverts to small rhombic crystals and its rubbery property disappears.。无定形硫是由大的线圈型螺旋链组成，这些螺旋链是S8环断裂后，首尾相连形成的。可以把无定型硫的全部性质描述为弹性硫，因为它伸缩的时候象一般的橡胶一样有弹性。几个小时后，弹性硫就转变为较小的斜方硫，弹性也随之消失。

ItS molecular structure provides for a covalence of three，as maybe expected from the three unpaired p electrons in its atomic structure, and each atom is attached to three others.它的分子结