章节大纲

  • A hand squeezing a saturated blue sponge over a sink drain, water dripping out.

    You can tell that this sponge is saturated with water because when it is squeezed, the water pours out. When something is saturated with water, it already holds as much water as possible. Compounds called , which contain only carbon and hydrogen, can also be saturated, but not with water.
    ::你可以发现,这块海绵与水相饱和,因为当它被挤压时,水就会溢出。当某个海绵与水相饱和时,水已经尽可能多了。 被称为碳和氢的化合物也可以被饱和,但水是不能饱和的。

    What Are Saturated Hydrocarbons?
    ::什么是饱和碳氢化合物?

    Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. They are the simplest class of hydrocarbons. They are called saturated because each carbon is bonded to as many hydrogen atoms as possible. In other words, the carbon atoms are saturated with hydrogen. You can see an example of a in the Figure . In this , named ethane, each carbon atom is bonded to three hydrogen atoms. In the structural formula, each dash (-) represents a single , in which two atoms share one pair of .
    ::饱和碳氢化合物是碳原子之间仅包含单一联系的碳氢化合物。它们是最简单的碳氢化合物类别。它们被称为饱和,因为每种碳与尽可能多的氢原子相连。换句话说,碳原子与氢饱和。您可以看到图中的一个示例。在这个名为乙烷的图中,每个碳原子与三个氢原子相连。在结构公式中,每个闪光(-)代表一个单一,其中两个原子共享一对氢原子。

    Structural formula of ethane (C2H6) showing carbon and hydrogen bonds.

    Q: What is the for ethane?
    ::问题:乙烷的用途是什么?

    A: The chemical formula is C 2 H 6 .
    ::A:化学式为C2H6。

    What’s in a Name?
    ::名字里有什么?

    Saturated hydrocarbons are given the general name of alkanes . The name of specific alkanes always ends in – ane . The first part of the name indicates how many carbon atoms each molecule of the alkane has. The smallest alkane is methane. It has just one carbon atom. The next largest is ethane with two carbon atoms. The chemical formulas and properties of methane, ethane, and other small alkanes are listed in the Table . The and points of alkanes are determined mainly by the number of carbon atoms they have. Alkanes with more carbon atoms generally boil and melt at higher temperatures.
    ::饱和碳氢化合物被命名为alkanes的一般名称。 特定的alkanes的名字总是以 - ane 结尾。 名称的第一部分表示碳原子的数量。 最小的alkane是甲烷。 它只有一个碳原子。 下一个最大的是两个碳原子的乙烷。 表中列出了甲烷、 乙烷和其他小型烷的化学公式和特性。 藻类的化学公式和特性主要取决于它们拥有的碳原子数量。 碳原子较多的Alkanes一般在更高的温度下沸腾和熔化。

    Alkane Chemical Formula Boiling Point(°C) Melting Point(°C) State (at 20 °C)
    Methane CH 4 -162 -183
    Ethane C 2 H 6 -89 -172 gas
    Propane C 3 H 8 -42 -188 gas
    Butane C 4 H 10 0 -138 gas
    Pentane C 5 H 12 36 -130
    Hexane C 6 H 14 69 -95 liquid
    Heptane C 7 H 16 98 -91 liquid
    Octane C 8 H 18 126 -57 liquid

    Q: The Table shows only alkanes that have relatively few carbon atoms. Some alkanes have many more carbon atoms. What properties might larger alkanes have?
    ::问题:本表仅显示碳原子相对较少的藻类。有些藻类有更多的碳原子。较大的藻类有哪些属性?

    A: Alkanes with more carbon atoms have higher boiling and melting points, so some of them are solids at room .
    ::A:碳原子较多的藻类有更高的沸点和熔点,

    Shapes of Alkanes
    ::阿尔卡内人形状

    Structural formulas are often used to represent hydrocarbon compounds because the molecules can have different shapes and a structural formula shows how the atoms are arranged. Hydrocarbons may form straight chains, branched chains, or rings (see Figure ). You can read about each type below.
    ::结构公式常常被用来代表碳氢化合物化合物,因为分子可以有不同的形状,而结构公式则显示原子是如何排列的。碳氢化合物可以形成直线链、分支链条或环(见图 ) 。您可以在下面阅读每种类型的信息。

    Structural formulas illustrating straight-chain, branched-chain, and cyclic alkanes in hydrocarbons.

    A) In a straight-chain molecule, all the carbon atoms are lined up in a row like cars of a train. The carbon atoms form the “backbone” of the molecule. B) In a branched-chain molecule, at least one of the carbon atoms branches off from the backbone. C) In a cyclic molecule, the chain of carbon atoms is joined at the two ends to form a ring. Each ring usually contains just five or six carbon atoms, but rings can join together to form larger molecules. A cyclic molecule generally has higher boiling and melting points than straight-chain and branched-chain molecules.
    ::A) 在直链分子中,所有碳原子都像火车的汽车一样排成一排。碳原子形成分子的“后骨 ” 。B) 在分链分子中,至少有一个碳原子离脊部的分支。C) 在循环分子中,碳原子链在两端结合形成一个环。每个环通常只有5或6个碳原子,但环可以组合成更大的分子。一个循环分子的沸点和熔点通常高于直链分子和分链分子。

    Summary
    ::摘要

    • Saturated hydrocarbons are hydrocarbons that contain only single bonds between carbon atoms. As a result, each carbon atom is bonded to as many hydrogen atoms as possible.
      ::饱和碳氢化合物是碳原子之间只有单一联系的碳氢化合物,因此,每个碳原子都与尽可能多的氢原子相连。
    • Saturated hydrocarbons are given the general name of alkanes. The name of specific alkanes always ends in –ane and has a prefix to indicate how many carbon atoms it has.
      ::饱和碳氢化合物被命名为alkanes的一般名称。 特定的alkanes的名称总是以 - ane 结尾,并有一个前缀来表示它有多少碳原子。
    • Hydrocarbons may form straight chains, branched chains, or rings. Ring-shaped hydrocarbons are called cyclic hydrocarbons.
      ::碳氢化合物可能形成直链、分环链或环,环形碳氢化合物被称为环状碳氢化合物。

    Review
    ::回顾

    1. What is a saturated hydrocarbon?
      ::什么是饱和碳氢化合物?
    2. How are saturated hydrocarbon compounds named?
      ::饱和碳氢化合物的名称如何?
    3. What are the name and chemical formula of the saturated hydrocarbon that has the following structural formula seen below?
      ::饱和碳氢化合物的名称和化学公式是什么,其结构公式如下:

    Structural formula of a saturated hydrocarbon, illustrating its molecular structure.

    1. Compare and contrast straight-chain, branched-chain, and cyclic alkanes.
      ::对比和对比直链、分链和环烷。

    Resources
    ::资源