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  • General

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  • 周期趋势: 离子弧度

    Close-up of peanuts in shells, some broken open showing brown inner peanuts.

    How are peanuts sold?
    ::花生怎么卖?

    Peanuts can be sold two ways.  The bare peanut without the shell (brown inner portion of peanut) can be purchased in jars and packages for casual munching or for cooking.  The size of the peanut in this situation is smaller than the peanut plus shell since the outer portion is missing.  If we add the shell to the peanut, we have a larger size for the combination.
    ::花生可以有两种方式出售。 没有贝壳的花生(花生的棕色内部部分)可以用罐子和包包购买,用于做饭或做饭。在这种情况下,花生的大小小于花生加花生壳的大小,因为外部分缺失了。如果我们在花生中加上贝壳,我们就可以使用更大的尺寸来组合。

    Electrons and are strongly attracted to one another.  The strength of that attraction and the relative numbers of the two particles in a given or have a significant influence on the size of that species.  When an atom loses one or more electrons, the resulting ion becomes smaller.  If electrons are added to the atom, the ion becomes larger.
    ::当原子失去一个或多个电子时,产生的离子就会变小。如果将电子添加到原子中,离子就会变大。

    Ionic Radius
    ::电离半径

    The ionic radius for an atom is measured in a crystal lattice , requiring a solid form for the .  These radii will differ somewhat depending upon the technique used. Usually X-ray crystallography is employed to determine the radius for an ion.
    ::原子的离子半径用晶体板测量,需要坚固的形状。这些半径视使用的技术而有所不同。通常使用X射线晶体法来确定离子的半径。

    Comparison of ionic sizes for elements in Groups 1, 2, 13, 16, and 17.

    Comparison of ion sizes to atom sizes for Groups 1, 2, 13, 16 and 17. The atoms are shown in gray. Groups 1, 2, and 13 are metals and form cations, shown in red. Groups 16 and 17 are nonmetals and form anions, shown in blue.
    ::第1、2、13、16和17组的离子大小与原子大小的比较以灰色显示,第1、2和13组的原子为金属和形体板,红色显示,第16和17组的原子为非金属和形体阴离子,蓝色显示。

    The removal of electrons always results in a that is considerably smaller than the parent atom. When the valence electron(s) are removed, the resulting ion has one fewer occupied principal energy level, so the cloud that remains is smaller. Another reason is that the remaining electrons are drawn closer to the nucleus because the protons now outnumber the electrons.  One other factor is the number of electrons removed.  The potassium atom has one electron removed to for the corresponding ion, while calcium loses two electrons.
    ::去除电子的结果总是比母原子要小得多。 当去除valence econom 时, 产生的离子会少一个占用的主要能量水平, 所以剩下的云会更小。 另一个原因是剩下的电子会更接近核, 因为质子现在超过了电子的数量。 另一个因素是去除电子的数量。 钾原子将一个电子移到相应的离子上, 而钙会损失两个电子 。

    The addition of electrons always results in an that is larger than the parent atom. When the electrons outnumber the protons, the overall attractive force that the protons have for the electrons is decreased. The electron cloud also spreads out because more electrons results in greater electron-electron repulsions. Notice that the group 16 ions are larger than the group 17 ions.  The group 16 each add two electrons while the group 17 elements add one electron per atom for form the anions.
    ::增加电子的结果总是大于母原子。 当电子数量超过质子时,质子对电子的总体吸引力就会减少。 电子云也会扩大, 因为更多的电子导致电子- 电子反射。 请注意, 16组离子大于17组离子。 16组每组增加2个电子, 而17组元素每原子增加1个电子, 形成离子 。

     

     

    Summary

    ::摘要

    • Ionic radius is determined by measuring the atom in a crystal lattice.
      ::电离半径是通过测量晶体层中的原子来确定的。
    • Removal of electrons results in an ion that is smaller than the parent element.
      ::电子的去除导致离子小于母元素。
    • Addition of electrons results in an ion that is larger than the parent atom.
      ::添加电子后产生的离子大于母原子。

    Review
    ::回顾

    1. How are ionic radii measured?
      ::如何测量离子弧度?
    2. Explain why the radius of the rubidium ion is smaller than the radius of the rubidium atom.
      ::解释为什么离子的半径小于原子的半径。
    3. Explain why the radius of the tellurium ion is larger than the radius of the tellurium atom.
      ::解释为什么离子的半径大于原子的半径。
    4. Why is the oxygen anion larger than the fluoride anion?
      ::为什么氧阴离子比氟化阴离子大?
    5. Why is the sodium cation larger than the magnesium cation?
      ::为什么钠的酸化比镁的酸化还要大?