化学专业英语

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Part Ⅰ Nomenclature
　　化学物质命名法
　　Chemical Element：化学元素
　　1.1.1 Text
　　1. Elements and compounds
　　A kind of matter consisting of atoms that all have nuclei with the same electric charge is called an element. For example， all of the atoms that contain nuclei with the charge +e， each nucleus having one electron attached to it to neutralize its charge， comprise the element hydrogen， and all of the atoms that contain nuclei with the charge+92e comprise the element uranium.
　　An element is a substance that is composed of atoms of one element only. An elementary substance is commonly called an element.
　　A compound is a substance that is composed of atoms of two or more different elements. These atoms of two or more different elements must be present in a definite numerical ratio， since compounds are defined as having a definite composition.
　　2. The names and symbols of the elements
　　The chemical symbols of the elements are used as abbreviations for their names. These symbols are usually the initial letters of the names， plus another letter when necessary. All but eleven of the elements are given a symbol corresponding to one or two letters in the English name of the element (the first letter is always capitalized and the second letter is never capitalized). One of these exceptions is tungsten， whose symbol (W) is derived from the German name of the element， Wolfram. The other ten have symbols derived from their Latin names. These are: stibium (Sb) for antimony， cuprum (Cu) for copper， aurum (Au) for gold， ferrum (Fe) for iron， plumbum (Pb) for lead， hydrargyrum (Hg) for mercury， kalium (K) for potassium， argentum (Ag) for silver， natrium (Na) for sodium， and stannum (Sn) for tin. The system of chemical symbols was proposed by the Swedish chemist J?ns Jakob Berzelius(1779—1848) in 1881. The elements are also shown in a special arrangement， the periodic table (Fig. 1.1).
　　Fig. 1.1 The periodic table
　　A symbol is used to represent an atom of an element， as well as the element itself. The symbol I represents the element iodine， and also may be used to mean the elementary substance. However I2 is the customary formula for the elementary substance， because it is known that elementary iodine consists of molecules containing two atoms in the solid and liquid states as well as in the gaseous state (except at very high temperature). In formulas showing composition or molecular structure the numerical subscript of an element gives the number of atoms of the element in the molecule.
　　1.1.2 New words
　　element n.元素 comprise v.构成，组成
　　consist of 由 组成 composition n.构成
　　atom n.原子 abbreviation n.缩写
　　nucleus n.(原子)核 the periodic table 元素周期表
　　electron n.电子 molecule n.分子的
　　1.1.3 Company reading 1: Groups and subgroups in the periodic table of the elements—A proposal of modification in the nomenclature
　　Since not all authors agree on specifying which are A and B subgroups in the periodic table of the elements， and since the letters A and B are arbitrary indications， either explanatory periphrases or misunderstandings are inevitable.
　　We propose to eliminate letters A and B， and propose to indicate the subgroups by letters referring directly to the electronic structure of atoms， that is by letters s， p， d and f according to the orbital block in which the subgroup is lying. For example， keeping in mind that the first group includes alkaline metals (which belong to s-block) and the transition metals copper， silver and gold (which belong to d-block)， one can indicate alkaline metals as subgroup Ⅰ-s and the other three metals as subgroup Ⅰ-d. Similar considerations can be drawn for the other groups， so that the table can be complete as reported in the Fig. 1.2.
　　According to our proposal， scandium， yttrium and lanthanum， which are transition elements， belong to group Ⅲ-d (Fig. 1.2); boron， aluminum， gallium， indium and thallium belong to group Ⅲ-p; the lanthanide and actinide elements， in accordance with their structure， belong to group Ⅲ-f.
　　Hydrogen is known to have no fixed place in the periodic table. According to someproperties， hydrogen is included in the first group though it is not an alkaline metal; but based on other properties， it might be included among the halogens. That is why hydrogen is said to occupy a place apart in the periodic system. Similar considerations can be drawn for helium， which because of chemical properties is included among noble gases; but considering its electronic structure (J=1/2) it could be included in group Ⅱ， as a lighter homologous to beryllium. According to our proposed new system， one can simply say that hydrogen belongs to group Ⅰ-s. Helium either may be considered as an element of group Ⅱ-s or assigned a place apart as a Ⅷ-s element (the other noble gases form group Ⅷ-p).
　　This proposal has been adopted as an experiment in a chemistry course for students at the University of Milan， and it has met with student fa