化学专业英语课文翻译

1、01 元素和元素周期表the number of protons in the nucleus of an atom is referred to as the atomic number, or proton number, z. the number of electrons in an electrically neutral atom is also equal to the atomic number, z. the total mass of an atom is determined very nearly by the total number of protons and n

2、eutrons in its nucleus. this total is called the mass number, a. the number of neutrons in an atom, the neutron number, is given by the quantity a-z.原子核内的质子数被称为原子序数,或质子数，z。一个电中性原子的电子数量也等于原子序数，z。原子的总质量接近核内质子数和中子数之和。这个总数被称为质量数a。中子在一个原子中的数量,中子数,给出了的数量为a-z。the term element refers to, a pure substance wi

3、th atoms all of a single kind. to the chemist the "kind" of atom is specified by its atomic number, since this is the property that determines its chemical behavior. at present all the atoms from z = 1 to z = 107 are known; there are 107 chemical elements. each chemical element has been gi

4、ven a name and a distinctive symbol. for most elements the symbol is simply the abbreviated form of the english name consisting of one or two letters, for example:单质是指,一个纯物质由一种原子组成的。化学家认为这种原子由它的原子数决定,因为它的性质决定了其化学行为。目前所有被知道的原子是z = 1 到z = 107的的原子，有107种化学元素。每一种化学元素被给以一个名字和一个独特的符号。对于大多数元素符号都仅仅是英文名称缩写为一个

5、或两个字母,例如:oxygen=o nitrogen = n neon=ne magnesium = mg氧=o 氮=n 氖=ne 镁=mgsome elements,which have been known for a long time,have symbols based on their latin names, for example:一些元素,很久以前就被知道的,它们的符号根据他们的拉丁名字符号,例如:iron=fe(ferrum) copper=cu(cuprum) lead=pb(plumbum)铁= =fe(ferrum) 铜= =cu(cuprum) 铅= =pb(plu

6、mbum)a complete listing of the elements may be found in table 1.一个完整的元素表可以被发现于表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

7、 and their compounds1. in 1869,d.mendeleev and l. meyer, working independently, proposed the periodic law. 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 num

8、ber, elements having closely similar properties will fall at definite intervals along the list. thus it is possible to arrange the list of elements in tabular form with elements having similar properties placed in vertical columns2. such an arrangement is called a periodic table。在十七世纪后期开始,在工作罗伯特

9、3;波以耳,提出当前公认的元素概念,大量的研究产生元素性质及其化合物的知识。在1869年,d.mendeleev和l. meyer,独立工作,提出了周期性的律法。在现代形式,法律规定的元素的性质是原子序数的周期函数。换句话说,当元素的按原子序数增加列清单，有相近的特性的元素落在了明确的间隔在清单上有明确间隔。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。这样的安排被称为一个周期表。each horizontal row of elements constitutes a period. it should be noted that the lengths of the

10、periods vary. there is a very short period containing only 2 elements, followed by two short periods of 8 elements each, and then two long periods of 18 elements each. the next period includes 32 elements, and the last period is apparently incomplete. with this arrangement, elements in the same vert

11、ical column have similar characteristics. these columns constitute the chemical families or groups. 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.每个水平排的横列元素构成

12、一个周期。但应该注意的是周期不同长度的。非常短的周期只包含两种元素,后面跟着两个短周期每个含8元素,然后两个长周期每个由18个元素组成。下一个周期包含32元素,最后一个周期明显不完整的。这样的安排，元素在同一纵列有相似的特性。这些纵列构成化学家庭或组。为首的两个8元素周期的成员被选定作为主族元素，其他组的成员被称为过渡或内在过渡元素。in the periodic table, a heavy stepped line divides the elements into metals and nonmetals. elements to the left of this line (with

13、the exception of hydrogen) are metals, while those to the right are nonmetals. this division is for convenience only; elements bordering the linethe metalloids-have properties characteristic of - both metals and nonmetals. it may be seen that most of the elements, including all the transition and in

14、ner transition elements, are metals.在元素周期表中,沉重的阶梯的线把元素分为金属和非金属元素。那条线的左边(除氢)是金属,而那些右边是非金属矿物等。这条线划分只是为了方便。那些与分隔线相临近的元素准金属，既有金属的性质，又有非金属的性质。可以看出，大部分的元素，是金属元素。except for hydrogen, a gas, the elements of group ia make up the alkali metal family. they are very reactive metals, and they are never found in

15、the elemental state in nature. however, their compounds are widespread. all the members of the alkali metal family, form ions having a charge of 1+ only. in contrast, the elements of group ib copper, silver, and goldare comparatively inert. they are similar to the alkali metals in that they exist as

16、 1+ ions in many of their compounds. however, as is characteristic of most transition elements, they form ions having other charges as well.除了氢元素一种气体元素外，a族的元素组成了碱金属。它们是非常活泼的金属，它们从未在自然界中以单质状态被发现。然而，它们的化合物是广泛分布的。碱金属的所有成员具有正一价的离子。与此相反，b族的元素铜、银、和金相对来说是惰性的。它们和碱金属的相似的，因为它们在化合物中以1+离子存在。但是和大多数过渡元素具有的特性一样，它们

17、也能形成其它价的离子。the elements of group iia are known as the alkaline earth metals. their characteristic ionic charge is 2+. these metals, particularly the last two members of the group, are almost as reactive as the alkali metals. the group iib elementszinc, cadmium, and mercury are less reactive than are

18、 those of group ii a5, but are more reactive than the neighboring elements of group ib. the characteristic charge on their ions is also 2+.a族的元素就是通常所说的碱土金属。它们离子的特征价是2+。这些金属，尤其是族中最后两个元素，几乎和碱金属一样活泼。b 族元素，锌、镉、和汞比那些a的元素活性低，但比临近的b族元素活泼。它们的特征价态也是2+。with the exception of boron, group iiia elements are also

19、 fairly reactive metals. aluminum appears to be inert toward reaction with air, but this behavior stems from the fact that the metal forms a thin, invisible film of aluminum oxide on the surface, which protects the bulk of the metal from further oxidation. the metals of group iiia form ions of 3+ ch

20、arge. group iiib consists of the metals scandium, yttrium, lanthanum, and actinium.除了硼以外，iiia元素相当活性金属。铝与空气反应后是惰性的，但这一表现源于这一事实：在金属表面形成了一个薄的，不可见的铝的氧化膜，该膜保护大部分金属不会被进一步氧化。a族金属形成3+的离子。b族金属由金属钪、钇、镧和锕组成。group iva consists of a nonmetal, carbon, two metalloids, silicon and germanium, and two metals, tin and

21、 lead. each of these elements forms some compounds with formulas which indicate that four other atoms are present per group iva atom, as, for example, carbon tetrachloride, gcl4. the group ivb metals titanium, zirconium, and hafnium also forms compounds in which each group ivb atom is combined with

22、four other atoms; these compounds are nonelectrolytes when pure.第族有一个非金属，碳，两个准金属硅和锗，还有两个金属，锡和铅组成。这些元素中每一个都形成一些化合物，这些化合物的分子式表明四个其他的原子出现在a族的原子周围，例如四氯化碳，ccl4。b族金属钛、锆和铪，也形成每个b族原子与四个其他族原子结合的化合物，这些化合物纯的时候是非电解质。the elements of group v a include three nonmetals nitrogen, phosphorus, and arsenicand two metal

23、s antimony and bismuth. although compounds with the formulas n2o5, pcl5, and ascl5 exist, none of them is ionic. these elements do form compounds-nitrides, phosphides, and arsenides in which ions having charges of minus three occur. the elements of group vb are all metals. these elements form such a

24、variety of different compounds that their characteristics are not easily generalized.a族元素包含三个非金属氮、磷、和砷，两种金属锑、铋。尽管它们存在分子式为n2o5,pcl5,ascl5的化合物,但它们都不是离子型化合物。这些元素形成的化合物氮化物，磷化物，砷化物，其中离子的价态都是负3价。b族元素都是金属，这些元素形成多种不同的化合物，它们的特点是不容易推广的。with the exception of polonium, the elements of group via are typical nonm

25、etals. they are sometimes known, as the, chalcogens, from the greek word meaning "ash formers". in their binary compounds with metals they exist as ions having a charge of 2-. the elements of group a are all nonmetals and are known as the halogens. from the greek term meaning "salt fo

26、rmers. ” they are the most reactive nonmetals and are capable of reacting with practically all the metals and with most nonmetals, including each other.除了钋的元素以外，a族元素都是典型的非金属。它们有时候被称为硫族，来自希腊字，意思是“灰源体”。它们与金属形成的二元化合物中以2-价的离子存在。a的元素都是非金属，被称为卤素。来自希腊语,意即“盐源体”。它们是最活泼的非金属，并能够与几乎所有的金属和非金属包括它们自己反应。the element

27、s of groups b, b, and viiib are all metals. they form such a wide 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.b,b,viiib元素都是金属。它们形成各种不同的化合物,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 behav

28、ior is illustrated by the fact that. excluding the first period,each period begins with a very reactive metal. successive element along the period show decreasing metallic character, eventually becoming nonmetals, and finally, in group a, a very reactive nonmetal is found. each period ends with a me

29、mber of the noble gas family.化学行为的周期性可以通过这样的事实阐明。除了第一周期,每一个周期开始于一个非常活泼的金属。周期中的连续元素显示，金属性逐渐降低，最终成为非金属。最后，在a,一个很活泼的非金属元素。每一个周期以一个惰性气体元素结束02非金属元素we noted earlier. that -nonmetals exhibit properties that are greatly different from those of the metals. as a rule, the nonmetals are poor conductors of elec

30、tricity (graphitic carbon is an exception) and heat; they are brittle, are often intensely colored, and show an unusually wide range of melting and boiling points. their molecular structures, usually involving ordinary covalent bonds, vary from the simple diatomic molecules of h2, cl2, i2, and n2 to

31、 the giant molecules of diamond, silicon and boron.我们早就注意到，非金属呈现出来的性质与金属有极大的不同。一般来说，非金属是电和热的不良导体（石墨碳是里例外）；他们是易碎的,有强烈的颜色,并表现出异常广泛的融点和沸点。他们的分子结构,通常是包括了普通的共价键的变化,从简单的双原子分子的h2,，cl2,i2和n2到大分子的金刚石，硅和硼。the nonmetals that are gases at room temperature are the low-molecular weight diatomic molecules and the

32、noble gases that exert very small intermolecular forces. as the molecular weight increases, we encounter a liquid (br2) and a solid (i2) whose vapor pressures also indicate small intermolecular forces. certain properties of a few nonmetals are listed in table 2.低分子量的非金属双原子分子在室温时是气体，且分子间的作用力小。随着分子量的增

33、大,我们遇到了液体(br2)和固体(i)，他们的蒸气压也表明分子间的作用力小。一些非金属的确定的性质都列在表2。simple diatomic molecules are not formed by the heavier members of groups v and vi at ordinary conditions. this is in direct contrast to the first members of these groups, n2 and o2. the difference arises because of the lower stability of bonds

34、 formed from p orbitals of the third and higher main energy levels as opposed to the second main energy level2. the larger atomic radii and more dense electron clouds of elements of the third period and higher do not allow good parallel overlap of p orbitals necessary for a strong bond. this is a ge

35、neral phenomenon strong bonds are formed only between elements of the second period. thus, elemental nitrogen and oxygen form stable molecules with both and bonds, but other members of their groups form more stable structures based on bonds only at ordinary conditions. note3 that group vii elements

36、form diatomic molecules, but bonds are not required for saturation of valence.通常条件下，简单的双原子分子并不是由第五族和第六族相对更重的成员形成。这直接与这两组的第一个成员,氮气和氧气形成对比。差别的出现时由于与第二主能级相反，第三和更高主能级的p轨道形成的键稳定性低。原子半径更大和电子云密度更密集的第三和更高周期元素不允许轨道上良好的平行重叠对于强键是必须的。这是一个普遍的现象强键只有在第二周期元素间形成。因此,元素氮、氧由 和键形成稳定的分子,但它们组族的其他成员,形成稳定结构键只有在普通的条件才行。注意第七组

37、族元素形成双原子分子,但键饱和度不做要求。sulfur exhibits allotropic forms. solid sulfur exists in two crystalline forms and in an amorphous form. rhombic sulfur is obtained by crystallization from a suitable solution, such as cs2, and it melts at 112°c. monoclinic sulfur is formed by cooling melted sulfur and it m

38、elts at 119°c. both forms of crystalline sulfur melt into s-gamma, which is composed of s8 molecules. the s8 molecules are puckered rings and survive heating to about 160°c. above 160°c, the s8 rings break open, and some of these fragments combine with each other to form a highly visc

39、ous mixture of irregularly shaped coils. at a range of higher temperatures the liquid sulfur becomes so viscous that it will not pour from its container. the color also changes from straw yellow at sulfur's melting point to a deep reddish-brown as it becomes more viscous.allotropic硫表有同素异形体。固体硫以两

40、结晶形式和一种无定形的形式存在。斜方硫是通过适当的溶液结晶得到的，如cs2,在112°c的融化。单斜硫是由冷却熔化的硫形成，它的熔点是119°c。两种结晶硫都熔化成s-gamma，由s8分子组成。s8的分子呈褶皱环状耐高温达160°c。超过160°c,s8环断开,其中的一些片段相互结合形成一个高粘度的、形状不规则的混合物。在较高的温度范围内，液态硫变得非常粘稠以至于不能从容器中倒出。颜色也从熔点是的稻草黄色变为深红褐色，因为它变得更加粘稠。as4 the boiling point of 444 °c is approached, the la

41、rge-coiled molecules of sulfur are partially degraded and the liquid sulfur decreases in viscosity. if the hot liquid sulfur is quenched by pouring it into cold water, the amorphous form of sulfur is produced. the structure of amorphous sulfur consists of large-coiled helices with eight sulfur atoms

42、 to each turn of the helix; the overall nature of amorphous sulfur is described as3 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.接近沸点444°c时,大盘绕分子形状的硫逐渐降解，并且液体硫粘度降低。如果把热的液体硫倒冷水里骤冷

43、,就会产生无定形硫。无定形硫由八个硫原子组成大螺旋盘绕,自然界中一切无定形硫被描述为橡胶状,是因为它像普通橡胶延伸。在几小时无定形硫又还原成斜方的晶体硫，其橡胶性消失。sulfur, an important raw material in industrial chemistry, occurs as the free element, as so2 in volcanic regions, as h2s in mineral waters, and in a variety of sulfide ores such as iron pyrite fes2, zinc blende zns,

44、 galena pbs and such, and in common formations of gypsum caso4 2h2o, anhydrite caso4, and barytes baso4 2h2o. sulfur, in one form or another, is used in large quantities for making sulfuric acid, fertilizers, insecticides, and paper.硫，工业化学的重要原料，像自由的元素那样出现，如的火山区so2,矿泉水中的h2s、和各种各样的硫矿石硫如黄铁矿fes2如铁、闪锌矿zn

45、s,方铅矿pbs等,共同形成的石膏caso42 h2o,硬石膏caso4,重晶石 baso42 h2o。硫，在一种或另一种形式,用于大量制造硫酸、肥料、杀虫剂、和纸张。sulfur in the form of so2 obtained in the roasting of sulfide ores is recovered and converted to sulfuric acid, although in previous years much of this so2 was discarded through exceptionally tall smokestacks. fortun

46、ately, it is now economically favorable to recover these gases, thus greatly reducing this type of atmospheric pollution. a typical roasting reaction involves the change:so2中的硫在硫化矿石焙烧中恢复和转化为硫酸,尽管在过去几年许多的二氧化硫通过特殊的高烟囱被摒弃。幸运的是,现在经济有利用回收这些气体,从而大幅度地减少这种大气污染。一个典型的焙烧反应涉及改变:2 zns + 3 o22 zno + 2 so22 zns +

47、3 o2-2氧化锌+ 2二氧化硫phosphorus, below 800 consists of tetratomic molecules, p4. its molecular structure provides for a covalence of three, as may be expected from the three unpaired p electrons in its atomic structure, and each atom is attached to three others6. instead of a strictly orthogonal orientat

48、ion, with the three bonds 90° to each other, the bond angles are only 60°. this supposedly strained structure is stabilized by the mutual interaction of the four atoms (each atom is bonded to the other three), but it is chemically the most active form of phosphorus. this form of phosphorus

49、, the white modification, is spontaneously combustible in air. when heated to 260°c it changes to red phosphorus, whose structure is obscure. red phosphorus is stable in air but, like all forms of phosphorus, it should be handled carefully because of its tendency to migrate to the bones when in

50、gested, resulting in serious physiological damage.磷，800以下由四原子分子组成p4。其分子结构提供价三个共价键,可以从原子结构中三个未成对p电子的预计,每一个原子与另外三个相连。取代完全的正交方向,与三方彼此90°,键角为60°。据称变形力结构是由四个稳定的原子相互作用,但是它是最活跃的磷形式。这种形式的磷、白色的变体,在空气中自然。当加热到260°c变为红磷,其结构是不清楚的。红色是在空气中磷稳定，但是,就像所有形式的磷,它应该谨慎处理因摄入体内后会进入到骨头,导致严重的生理伤害。elemental carbo

51、n exists in one of two crystalline structures diamond and graphite. the diamond structure, based on tetrahedral bonding of hybridized sp3 orbitals, is encountered among group iv elements. we may expect that as the bond length increases, the hardness of the diamond-type crystal decreases. although th

52、e tetrahedral structure persists among the elements in this group carbon, silicon, germanium, and gray tin the interatomic distances increase from 1.54 a for carbon to 2.80 a for gray tin. consequently . the bond strengths among the four elements range from very strong to quite weak. in fact, gray t

53、in is so soft that it exists in the form of microcrystals or merely as a powder. typical of the group iv diamond-type crystalline elements, it is a nonconductor and shows other nonmetallic properties7.元素碳以两种晶体结构存在金刚石和石墨。金刚石结构基于四面体的sp3的杂化轨道结合，是在第四族元素中遇到的。我们可以猜想，随着键长增加,金刚石晶形硬度降低。虽然四面体结构在这些元素中存在这个-碳、硅、

54、锗,和灰锡-原子距离由碳的1.54提高到灰锡的2.80 a。因此。四大元素的键作用力范围有非常强到相当薄弱。事实上,灰锡是柔软的,它以微晶形式存在，或只是一种粉末。第四主族钻石结晶型结晶元素的典型，他是一个绝缘体并显示其它非金属性质。06无机化合物的分类the classes of compoundsthousands and tens of thousands of compounds are known to the chemist today. it would be impossible to learn properties and behavior of even a fracti

55、on of this number if it had to be done on the basis of individual compounds1. fortunately, most chemical compounds can be grouped together in a few classes. then, if we can properly classify a compound . we are at once aware of the general properties of the compound from knowledge of the properties

56、of that class or group of compounds. for example. hcl is classed as an acid. and by becoming familiar with the behavior of acids as a distinct class, we are at once aware of the general properties of the compound2. a great many of the compounds we are to study may be classified as acids, bases, salt

57、s, metallic oxides, or nonmetallic oxides. of these five classes of compounds, the first three acids, bases, and salts are by far the most important3今天成千上万种化合物已被化学家所知。如果根据个别化合物来了解这么多化合物的性质和行为，即使是其中一小部分也是不可能的。所幸的是，大多数化合物可以被归为几类。这样，如果我们可以真确的对一个化合物进行分类。我们就可以根据这类化合物的性质知道这个化合物的一般性质。例如，hcl是一种酸，因为已经熟悉酸的性质，

58、我们就可以立即知道这一化合物的一般性质。我们学过的大多数化合物可以分为酸、碱、盐、金属氧化物、非金属氧化物。这五类化合物，前三种酸、碱、盐是最重要的。 when an acid, base, or salt is dissolved in water the resulting solution is a conductor of the electric current and is termed an electrolyte. if no conduction of current occurs, the compound is known as a nonelectrolyte.当一个酸

59、、碱、盐溶于水中的溶液是一种电流的导体被称为电解质。如果没电流产生则该化合物被称为非电解质。classification of common compounds常见的化合物分类by looking at the chemical formulas we may classify many common compounds in the following way.通过观察化学公式中我们将许多普通化合物以如下方式分类。1. acids, in the conventional sense, may be recognized by noting that the h is written first in the formula and that the rest of the compound is generally nonmetallic. ex., hcl, h2so4, hclo.1。酸,用常规的感觉,会被注意到的h被写在分