【正文】 Natural pounds refer to those that are produced by plants or animals. Many of these are still extracted from natural sources because they would be far too expensive to be produced artificially. Examples include most sugars, some alkaloids and terpenoids, certain nutrients such as vitamin B12, and in general, those natural products with large or stereoisometrically plicated molecules present in reasonable concentrations in living pounds of prime importance in biochemistry are antigens, carbohydrates, enzymes, hormones, lipids and fatty acids, nucleic acids, proteins, peptides and amino acids, vitamins. 天然化合物是指那些由植物或動物生產(chǎn)的，其中許多天然產(chǎn)物仍然來源于天然原料的提取，因為人工生產(chǎn)將過于昂貴。 Organic pounds may be classified in a variety of ways. One major distinction is between natural and synthetic pounds. Organic pounds can also be classified or subdivided by the presence of heteroatoms, . anometallic pounds which feature bonds between carbon and a metal, and anophosphorus pounds which feature bonds between carbon and a phosphorus. Another distinction, based upon the size of anic pounds,distinguishes between small molecules and polymers. 有機化合物可用各種不同的形式進行分類。 An anic pound is any member of a large class of chemical pounds whose molecules contain carbon. There is no official definition of an anic pound. Some text books define an anic pound as one containing one or more CH bonds。 Organic pounds can be found in nature or they can be synthesized in the laboratory. An anic substance is not the same as a natural substance. A natural material means that it is essentially the same as it was found in nature, but anic means that it is carbon based. A printed circuit board is an example of an anic substrate because the laminate material is made of glass fibers in an epoxy, and epoxies are carbon based. 有機化合物即可存在于自然界，也可以在實驗室合成。生物體主要組成是水和有機物如：蛋白質(zhì)，碳水化合物，脂肪，核酸，激素，維生素和其他成分。配位化合物（或絡合物）是無機化合物的一個重要門類，其分子中有一個中心金屬原子（通常是一個過渡元素）結(jié)合到一個或多個非金屬配體（無機的、有機的或兩者兼有）。盡管地殼的組成部分是很清楚的，但在深部地幔礦化過程及其組成的研究依然非常活躍。 Minerals are mainly oxides and sulfides, which are strictly inanic. In fact, most of the earth and the universe is inanic. Although the ponents of the Earth39。 for example, carbon monoxide, carbon dioxide, carbonates, cyanides, cyanates, carbides. In general, however, the workers in these areas are not concerned about strict range from substances that are strictly inanic, such as [Co(NH3)6]Cl3, to anometallic pounds such as Fe(C5H5)2 and extending to bioinanic pounds, such as the hydrogenase enzymes. 許多無機化合物包含碳 。相反，多數(shù)有機化合物歷來視為來源于生物。 Mercuric oxide is a dense, orangered powder posed of a ratio of one atom of mercury to one atom of oxygen. Its position by weight is percent mercury and percent oxygen, when it is heated to temperatures greater than 3600C, a colorless gas, oxygen, and a silvery liquid metal, mercury, are produced. Here again are specific physical and chemical properties belonging to mercuric oxide and to no other substance. Thus, a pound may be identified and distinguished from all other pounds by its characteristic properties. when引導時間狀語從句，其實表示一種條件 belonging to mercuric oxide and to no other substance是 properties的定語 ? 氧化汞是一種致密，橙紅色粉末，由 1:1的汞原子和氧原子組成。每個化合物都是獨一無二的并且具有獨特的物理和化學性質(zhì)。 There are over three million known（已知的） pounds, with no end in sight as to the number that can and will be prepared in the future. Each pound is unique and has characteristic physical and chemical properties. Let us consider in some detail two pounds water and mercuric oxide. Water is a colorless, odorless, tasteless liquid that can be changed to a solid, ice, at 00C and to a gas, steam at 100℃ ?. It is posed of two atoms of hydrogen and one atom of oxygen per molecule, which represents percent hydrogen and percent oxygen by weight?. Water reacts chemically with sodium to produce hydrogen gas and sodium hydroxide, with lime to produce calcium hydroxide, and with sulfur trioxide to produce sulfuric acid. No other pound has all these exact physical and chemical properties。 ordinary table sugar (sucrose, C12H22O11) contains a ratio of 12 atoms of carbon to 22 atoms of hydrogen to 11 atoms of oxygen. These atoms are held together in the pound by chemical bonds. 化合物既可以由陰陽離子靠靜電吸引在一起的形式存在。 An ion is a positive or negative electrically charged atom or group of atoms. The ions in a pound are held together in a crystalline structure by the attractive forces of their positive and negative charges. Compounds consisting of ions do not exist as molecules. So