应用化学(万有志)专业英语unit7化学键翻译.docVIP

PART TWO THE FUNDATIONS OF CHEMISTRYUnit7Chemical Bonds化学键There are approximately 100 chemical elements. 世界上大概有100种元素。There are millions of chemical compound, and about 600000 new compounds are prepared every year. 现有数百万种化合物，而且每年有60万种新化合物被合成出来。To form these compounds, atoms of different elements must be held together in specific combinations. be held togetherin specific combinations 以特定的方式为了合成这些化合物，不同种类的原子必须以特定方式结合在一起。Chemical bonds are the forces that maintain these arrangements. That引导定语从句，修饰forces化学键是保持这种结合状态的力。Chemical bonding also plays a role in determining the state of matter. plays a role 起作用化学键同时在决定物质状态方面也起作用。At room temperature, water is a liquid, carbon dioxide is a gas, and table salt is a solid because of differences in chemical bonding.在室温下，水是液体，二氧化碳是气体，晶体盐是固体，是由于化学键的不同。As scientists developed an understanding of the nature of chemical bonding, they gained the ability to manipulate the structure of compounds. As引导原因状语从句to manipulate the structure of compounds不定式短语做宾补随着化学家对化学键认识的发展，他们获得了控制化合物结构的能力。Dynamite, birth control pills, synthetic fibers, and a thousand other products were fashioned in chemical laboratories and () have dramatically changed the way we live. 炸药、避孕药、合成纤维，和数以千计的其他产品在实验室中被合成出来，并且魔术般的改变了我们的生活。We are now entering an era that promises (some would say forebodes) even greater change.我们现在进入了一个可望（或者说预言）更大变化的时代。The DNA molecular the chemical basis of heredity carries its genetic message in its bonds in DNA. 分子DNA遗传物质的基础以它的键传递遗传信息。Whether an organism is fish, fowl, hippopotamus, or human is determined by the arrangement of bonds in DNA.Whether an organism is fish, fowl, hippopotamus, or human做主语无论一个生物体是鱼、家禽、河马还是人，都是由于DNA的键的组合方式决定的。Scientists already have the ability to rearrange these bonds, and this ability has given them limited control over the structure of living matter. Them, limited control over the structure of living matter双宾语科学家已经获得了重组这些键的能力，而这种能力给了他们有限的对生物体结构的控制。As techniques of genetic engineering improve, scientists may literally be able to custom-tailor genes.随着基因工程的发展，科学家们将最终设计出符合条件的基因。Let us begin our consideration of chemical bonding so that we, too, can understand the forces that control the structure of matter, living and nonliving.That引导定语从句修饰forces，living and nonliving，动名词，matter得同位语，修饰matter让我们开始对化学键的论述，并由此理解控制物质，包括有生命体和无生命体，的结构的力。Ionic Bond 离子键Let us look at an atom of the element sodium (Na). 我们看一下钠原子。It has 11 electrons, of which two are in the first energy level, eight in the second, and one in the third. the first energy level第一能级the second energy level第二能级the third energy level第三能级It has 11 electrons, of which two are in the first energy level, eight are in the second energy level, and one is in the third energy level. 它有11个电子，其中2个电子在第一能级，8个电子在第二能级，1个电子在第三能级。If the sodium atom could get rid of an electron, then the product, called a sodium ion, would have the same electron structure as an atom of the noble gas neon (Ne).called a sodium ion 分词短语做非限定，修饰productnoble gas如果钠原子能够失去1个电子，产物称为钠离子，就和惰性气体氖（Ne）具有相同的电子结构。Let us immediately emphasize that the sodium ion (Na+) and neon atom (Ne) are not identical. 让我们首先强调一下，钠离子（Na）和氖原子（Ne）并不相同。The electron arrangement is the same, but the nuclei and resulting charges are not. electron arrangement 电子排布resulting charges最终电荷电子排布是相同的，而核及最终电荷是不同的。As long as sodium keeps its 11 protons, it is still a form of sodium, but it is the sodium ion, not the sodium atom. 只要钠带有11个质子，它就一直是钠，但它是钠离子而不是钠原子。Ions are charged particles, particles in which the number of electrons does not equal the number of protons. in which 引导非限定定语从句。离子是一种带电粒子，一种电子数不等于质子数的粒子。Positively charged ions are called cations (pronounced “cat-ions”). The sodium ion is a cation.带正电荷的粒子称为阳离子（音为阳离子）。钠离子是阳离子。If a chlorine atom (Cl) could gain an electron, it would have the same electron structure as the noble gas argon (Ar).如果氯原子（Cl）能够得到一个电子，它将与惰性气体氩（Ar）具有相同的电子结构。The chlorine atom, having gained an electron, becomes negatively charged. It has 17 protons (17+) and 18 electrons (18-). It is written Cl- and it called a chloride ion.having gained an electron动名词形式做定语，修饰chlorine atom获得一个电子的氯原子带有负电荷。它具有17个质子（17+）和18个电子（18），写作Cl，称为氯离子。Negatively charged ions are called anions (pronounced “ann-ions”). The chloride ion is an anion.带负电荷的粒子称为阴离子（音为阴离子）。钠离子是阴离子。A sodium forms a less reactive species, a sodium ion, by losing an electron. a less reactive species, a sodium ion同位语钠原子通过失去一个电子形成不活泼的钠离子。A chlorine atom becomes a less reactive chloride ion by gaining an electron. 氯原子通过得到一个电子形成不活泼的氯原子。A chlorine atom cannot just pluck an electron from empty space, nor can a sodium atom kick out an electron unless something else is willing to take it on. empty space 空白空间、真空空间，意为“凭空”、“无根据”nor作连词，与助动词和情态动词连用，句中主语与动词倒置。He cant see, nor could he hear until a month ago. 他现在看不见，一个月之前他还听不见。She isnt rich, nor do I image that she ever will be. 她现在不富，我看她将来也富不了。kick out 逐出、解雇、开除；意为“失去”They kicked him out (of the club) for fighting.他因为斗殴而被开除（出俱乐部）。something else 别的东西take on 接纳、承受氯原子不能凭空获得一个电子，而钠原子也不能凭空失去一个电子，除非别的东西愿接受电子。What happens when sodium come into contact with chlorine? The obvious. A chlorine atom removes an electron from a sodium e into contact 接触、相遇The obvious 显而易见的当钠与氯接触时发现了什么？很明显，氯原子从钠原子处拿走了一个电子。The sodium ion and the chloride ion have electron arrangements (electron configurations) like those of two noble gases (neon and argon, respectively). electron arrangement电子排布electron configurations电子结构钠离子和氯离子的电子排布（电子结构）就象两个惰性气体（氖和氩，相应的）一样。Not only do the ions have stable octets of electrons, they also have opposite charges. 它们具有稳定的电子八耦体结构，而且有相反的电荷。Everyone knows that opposites attract. 每个人都知道异性相吸。While this rule of thumb may not always work when applied to people, it works quite well for cations and anions. rule of thumb单凭经验来做的方法，比较粗糙的方法，约略得衡量（或估计）虽然这种经验对人未必适用，但对阴阳离子是非常适用的。The attractive force between oppositely charged ions is called an ionic bond, and the combination of sodium ions and chloride ions is the compound sodium chloride or table salt.相反电荷之间的吸引力称为离子键，钠离子和氯离子结合为化合物氯化钠和食盐。Covalent Bonds共价键One might expect a hydrogen atom, with its one electron, to acquire another electron and assume the helium configuration. to acquire another electron and (to) assume the helium configuration不定式做宾补人们也许希望带有一个电子的氢原子，获得另一个电子并呈现氦的结构。Indeed, hydrogen atom do just that in the presence of atoms of a reactive metal such as lithium, that is, a metal that finds it easy to give up an electron.do代替上句, just that引导条件状语reactive metal活泼金属that is 插入语，也就是说a metal，reactive metal的同位语，that引导定语从句修饰a metal实际上，氢原子只有在活泼金属如锂的存在下确实发生了这样的反应，活泼金属就是很容易失去电子的金属。But what if there are no other kinds of atoms around? 但是，如果周围没有其他种类的原子呢？What if there are only hydrogen atoms (as in a sample of the pure element)? 如果只有氢原子（作为纯元素样品）呢？One hydrogen atoms can scarcely grab an electrons from another, for among hydrogen atoms all have equal attraction for electrons (Even more important, perhaps, hydrogen atoms do not have a tendency to lose electrons at all, for the result would be a highly reactive bare proton the hydrogen nucleus.) Even more important更重要的一个氢原子几乎不能从另一个氢原子处获取电子，因为氢原子具有相同的电子吸引力（更重要的，可能是，氢原子没有失去电子的倾向，因为那样的结果是生成高度活泼的裸露质子氢原子核）。Still hydrogen wants a duet of electrons like heliums. 而且氢原子希望象氦原子那样拥有2个电子。If one hydrogen cannot capture anothers electron, the two atoms can compromise by sharing their electrons.如果一个氢原子不能获取另一个氢原子的电子，这两个原子则通过共用电子的方式解决。It is as if the two hydrogen atoms, in approaching one another, get their electron clouds or orbitals so thoroughly enmeshed that they cannot easily pull them apart again.in approaching one another 做插入语as if与as though 用法相同，意为：宛如、仿佛、好像。as if后面常用过去时表示现在，说明所作的比较“不是真的”。You look as if youd seen a ghost.在非正式文体中，常用like代替as if。 He sat there smiling like it was his birthday.就好像两个氢原子，当它们互相接近时，其电子云充分重叠，以至于难于再分开。Moat of the time the electrons are located between the two nuclei. 大部分时间电子位于两个原子之间。The electron-dot formula usually used, H:H, is therefore a fairly good picture (If we were to attribute human qualities to hydrogen atoms, we would suggest that they are a bit nearsighted. Each one looks around, sees two electrons, and decides that these electrons are its very own and that therefore it has as arrangement like that of helium, one of the noble gases.) electron-dot formula 电子式noble gase惰性气体经常用电子式H：H表示，这是一个很好的画面（如果我们以人的品性归于氢原子，我们说它们有些目光短浅。每个氢原子看看周围，看到两个电子，就认为这些电子是自己的，它们就有了象惰性气体氦那样的电子排布）。This combination of hydrogen atoms is called a hydrogen molecule. 这种氢原子化合物叫氢分子。Molecules are discrete groups of atoms held together by shared pairs of electrons. The bond formed by a shared pair of electrons is called a covenlent bond.分子是通过共用电子对将两个分离的原子结合在一起。通过共用电子对形成的键称为共价键。A chlorine atom will pick up an extra electron from anything willing to give one up. 氯原子可以从任何愿意失去一个电子的原子处得到一个电子。But, again, what if the only thing around is another chlorine atom? 但是，如果周围只有另一个氯原子又会怎样？Chlorine atoms, too, can attain a more stable arrangement by sharing a pair of electrons.氯原子同样也是通过共用电子对达到稳定结构。Each chlorine atom in the chlorine molecule counts eight electrons around itself and concludes that it has an arrangement like that of the noble gas argon. that it has an arrangement like that of the noble gas argon.宾语从句氯分子中每个氯原子周围都有8个电子，并且可以断定它具有惰性气体氩一样的排布。The shared pair of electrons in the chlorine molecule also creates a covalent bond.氯分子中共用的一对电子同样形成共价键。For simplicity, the hydrogen molecule is often represented as H2 and the chlorine molecule as Cl2. the chlorine molecule as Cl2：the chlorine molecule is often represented as Cl2为了简化，氢分子常写成H2，氯分子常写成Cl2。The subscripts indicate two atoms per molecule. 这个下标表示每个分子中有2个原子。In each case, the covalent bond between the atoms is understood. Sometimes the covalent bond is indicated by a dash, H-H and Cl-Cl.在每种情况下，原子之间的共价键都可以理解，有时共价键也用一个短线表示HH和ClCl。：Let us be sure we understand the meaning of numbers in formulas. 让我们确信我们理解公式中数字的意义。Take a moment to establish in your mind the difference among the following: H，H2，2H，2 H2，H2O，2 H2O. 花点时间来搞清楚下面数字的不同：H，H2，2H，2 H2，H2O，2 H2O。Is it clear to you that although H represents a single atom of hydrogen, H2 implies two atoms of H bonded together, whereas 2H represents two separate, free, and independent atoms of H? That引导实际主语你是否明白H代表分离的氢原子，H2代表两个H结合而成的氢分子，而2H代表分离的、自由的、孤立的氢原子吗？On the other hand, the meaning of H2 in H2O is totally different from that of H2 as a molecule. 另一方面， H2在H2O中的意思与作为一种分子的H2完全不同。In H2O it means that two atoms of H are individually attached to O（not to themselves!） to form a molecule of water. 在 H2O中表示两个H分别吸引O（而不是它们自己！）来形成一个水分子。Finally, 2 H2O simply refers to two individual molecules of water.最后，2 H2O代表两个独立的水分子。Covalent bonds are not limited to the sharing of one pair of electrons. Consider, for example, the nitrogen atom. Its electron-dot symbol is：共价键不限于分享一对电子。例如，对于氮原子。它的电子式是：Now, after all we have learned about the octet rule we know that this electron arrangement is not complete. octet rule八耦体规则现在，我们学习了八耦体规则。我们知道这个电子排布是不饱和的。It has only five electrons in its outermost energy level. outermost energy level外层电子能级在它的外层电子能级上只有5个电子。It could shared a pair of electrons with another nitrogen atom and would then look like this： 它可以与另一个氮原子共用一对电子而变成如下形式： The situation has not improved a great deal. 情况并没有发生太大变化。Each nitrogen atom in this arrangement has only six electrons surrouding it (not eight). 每个氮原子周围电子排布只有6个电子（不是8个）。Each nitrogen atom has two electrons hanging out there without partners, so, to solve the dilemma, each nitrogen atom shares two additional pairs of electrons, for a total of three pairs.hanging out把伸出、挂出，上身伸出（窗外），闲荡每个氮原子都有两个未成对电子，所以，为了解决这一矛盾，每个氮原子共用另外两对电子，共3对电子In drawing the nitrogen molecule (N2), we have placed all the electrons being shared by the two atoms in the space between the two atoms. being shared by the two atoms分词短语做定语写氮分子（N2）时，我们把两个原子的所有的共用电子都写在两个原子中间。Each nitrogen atom has now satisfied the octet rule. 每个氮原子都满足了八耦体规则。A molecule in which three pairs of electrons (a total of six individual electron) are being shared is said to contain a triple bond. in which three pairs of electrons (a total of six individual electron) are being shared定语从句triple bond三键一个分子共享三对电子（共6个单个电子）被称为含有三键。Each nitrogen atom also has an unshared pair of electrons. 每个氮原子还含有一对孤对电子。Note that we could have drawn the unshared pair of electrons above or below the atomic symbol. atomic symbol 元素符号注意我们可以把孤对电子写在元素符号的上方或下方。Such a drawing would represent the same molecule.这些写法代表相同的分子。Polar Covalent Bonds 极性共价键So far we have seen that atoms combine in two different ways. So far迄今为止，就此范围（或程度）说来迄今为止，我们看到了两种不同的原子结合方式。Some that are quite different in electron structure (from the opposite ends of the periodic table) react by the complete transfer of one or more electrons from one atom to another (ionic bond formation). from the opposite ends of the periodic table周期表相对的两端句子结构：somereact byTransfer 名词那些原子结构截然不同（周期表左右两端）的原子，一个将一个或数个电子由一个原子完全传递到另一个原子的方式反应（离子键形成）。Atoms that are identical combine by sharing one or more pairs of electrons (covalent bond formation). 相同的原子通过共用一对或多对电子（共价键形成）而结合。Now let us look at some “in-betweeners”.现在让我们看一下“居于中间者”。Hydrogen and chlorine react to form a colorless, toxic gas called hydrogen chloride. hydrogen chloride 氯化氢氢与氯反应生成一种无色、有毒的气体氯化氢。This reaction can be represented schematically by这个反应可由下式表示：H Cl HCl 或（HCl）Both the hydrogen atom and the chlorine atom want an electron, so they compromise by sharing and form a covalent bond. 氢原子和氯原子都想得到一个电子，所以它们通过共用电子对结合并形成共价键。Since the substances hydrogen and chlorine actually consist of diatomic molecules rather than single atoms, the reaction is more accurately represented by the scheme.diatomic molecules 二原子分子由于氢和氯实际上是二原子分子而不是单个原子，反应写成下式更准确This can be more simply written as简写为H2 Cl2 2HClOne might reasonably ask why the hydrogen molecule and the chlorine molecule react at all. 有人也许会问为什么氢分子和氯分子能够完全反应。Have we not just explained that they themselves were formed provide a more stable arrangement of electrons? 宾语我们不是已经解释了它们本身形成了相对稳定的电子排布了吗？Yes, indeed, we say that. But there is stable and there is more stable. 是的，我们说过这些，但这有稳定和更稳定。The chlorine molecule represents a more stable arrangement than separate chlorine atoms, but, given the opportunity, a chlorine atom would rather bond to hydrogen than（bond）to another chlorine atom.would ratherthan含有选择得意思，“宁可而不”would rather与than后面为平行结构氯分子代表着比单独的氯原子更稳定的排列，但是，若有机会，氯原子宁可与氢成键而不愿与另一个氯成键。In a molecule of hydrogen chloride, a chlorine atom shares a pair of electrons with a hydrogen atom. 在氯化氢分子中，氯原子和氢原子共用一对电子。In this case, and in others we shall consider, sharing does not mean sharing equally. 在这种情况下，以及我们能想到的其他情况，共用并不意味着完全分享。Some atoms within molecules attract electrons more strongly than do other atoms. 分子中一些原子吸引电子的能力比其他原子强。The term electronegativity is used to describe the affinity of an element in a molecule for electrons. 电负性是用来描述分子中原子的亲和力的。The higher the electronegativity, the more strongly the atoms of an element attract electrons to themselves. 电负性越大，原子吸引电子的能力越强。The most electronegativity element is fluorine, which is located in the upper right corner of the periodic table. 电负性最大的元素是氟，它处于元素周期表的右上角。The electronegativity of elements decreases as one moves away from fluorine in the periodic table. 在周期表中，离氟越远，元素的电负性越弱。Thus electronegativity decreases as one moves down a group (column) or left across a period (row).down a group (column) 由族（列）向下left across a period (row) 由周期（行）向左所以，由族（列）向下或由周期（行）向左，电负性减弱。I. Comprehension 1. What is the main idea of the paragraph? A A. There are so many kinds of chemical bonds.B. How does the ionic bond come into being.C. The noble gases are stable.D. Can sodium atoms and chlorine atoms react with each other to form a stable arrangement of electrons. 2. What is the authors meaning by saying “even atoms have their own standards of beauty”? B A. Atoms can detect whether an electron arrangement is beautiful or not.B. There are standards or rules that can determine if an electron arrangement is favored or not.C. Atoms are more favored a beautiful electron arrangement than an ugly one.D. We can beautify atoms by their standards. 3. Whats “the standards of beauty” of atoms? C A. An octet (eight outer electrons).B. A duet (two outer electrons).C. A and B.D. There is no such standards. 4. Are the sodium ion (Na+) and the neon atom (Ne) identical? E A. Yes, they have same electron numbers.B. Yes, they have same electron arrangement.C. No, sodium ion is still a form of sodium, not atom but cations.D. No, sodium ion is a charged particle, while the neon atom is a neutral one.E. C and D. 5. It is impossible for Tom to judge such important affair B A. as a rule of thumb.B. by rule of thumb.C. though a rule of thumb.D. by experiment. 6. What happens during Na + Cl Na+Cl- D A. the nuclei of each ions are changed.B. the inner energy level of electrons chan