Section outline

  • General

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  • 电压电

    Stained paper illustrating a chemical reaction, possibly involving diffusion of a purple substance.

    What makes a particular element very reactive and another element non-reactive?
    ::是什么使某一要素非常被动反应,而另一要素则非反应反应?

    A involves either removal, electron addition, or electron sharing. The path a specific will take depends on where the electrons are in the and how many there are.
    ::A 涉及清除、 电子添加或电子共享。 具体路径取决于电子的位置和数量 。

    of Second-Period Elements
    Element Name Symbol Electron Configuration
    Lithium Li 3 1 s 2 2 s 1
    Beryllium Be 4 1 s 2 2 s 2
    Boron B 5 1 s 2 2 s 2 2 p 1
    Carbon C 6 1 s 2 2 s 2 2 p 2
    Nitrogen N 7 1 s 2 2 s 2 2 p 3
    Oxygen O 8 1 s 2 2 s 2 2 p 4
    Fluorine F 9 1 s 2 2 s 2 2 p 5
    Neon Ne 10 1 s 2 2 s 2 2 p 6

    In the study of chemical reactivity, we will find that the electrons in the outermost principal energy level are very important and so they are given a special name. Valence electrons are the electrons in the highest occupied principal energy level of an atom. In the second period elements listed above, the two electrons in the 1 s sublevel are called inner-shell electrons and are not involved directly in the element’s reactivity or in the formation of compounds. Lithium has a single electron in the second principal energy level and so we say that lithium has one valence electron. Beryllium has two valence electrons. How many valence electrons does boron have? You must recognize that the second principal energy level consists of both the 2 s and the 2 p sublevels and so the answer is three. In fact, the number of valence electrons goes up by one for each step across a period until the last element is reached. Neon, with its configuration ending in s 2 p 6 , has eight valence electrons.
    ::在化学反应研究中,我们将发现,外层主要能源水平中的电子非常重要,因此它们被命名为特殊名称。 valence econens 是原子中最高占用主要能源水平的电子。 在上文列出的第二个时期, 1级以下的两个电子被称为内壳电子, 并不直接参与元素反应或化合物的形成。 锂在第二位主要能源水平上有一个单电子。 因此,我们说锂有一个valence 电子。 有两个valence 电子。 有多少valence 电子是波伦的? 您必须认识到, 第二位主要能源水平由 2 和 2p 子 级组成, 因此答案是 3 。 事实上, 在到达最后一个元素之前, valence 电子的数量每一步都会上升1 。 Neon , 其配置以 S2p6 结尾有 8 valence 电子 。

      

     

    Summary
    ::摘要

    • Valence electrons are the outer-shell electrons of an atom.
      ::等离子电子是原子的外壳电子。
    • Valence electrons determine the reactivity of an atom.
      ::等离子电子决定原子的反活动。

    Review
    ::回顾

    1. Define valence electron.
      ::定义物价电子。
    2. Define inner shell electron.
      ::定义内壳电子。
    3. How many valence electrons are there in fluorine?
      ::氟化物中有多少值钱电子?
    4. What are the 2 s electrons in nitrogen?
      ::氮中的2电子是什么?
    5. How many inner shell electrons are there in beryllium?
      ::中有多少内壳电子?