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  • 扬

    lesson content

    The incredible green lights in this cold northern sky consist of charged particles known as . Their swirling pattern is caused by the pull of Earth’s magnetic field . Called the northern lights, this phenomenon of nature shows that ions respond to a magnetic field. Do you know what ions are? Read on to find out.
    ::寒冷的北方天空中令人难以置信的绿光是由电磁粒子组成的。它们的旋转模式是由地球磁场的拉动造成的。称为北极光,这种自然现象表明离子对磁场有反应。你知道什么是离子吗?继续阅读以了解。

    Atoms Are Neutral
    ::原子是中立的

    The northern lights aren’t caused by atoms, because atoms are not charged particles. An always has the same number of electrons as . Electrons have an electric charge of -1 and protons have an electric charge of +1. Therefore, the charges of an atom’s electrons and protons “cancel out.” This explains why atoms are neutral in electric charge.
    ::北极光不是由原子引起的,因为原子没有充电粒子。 电量总是与电量相同。 电量为-1,质子的电量为+1。 因此,原子电子和质子的电量“取消 ” 。 这就是为什么原子在电量中是中性的。

    Q: What would happen to an atom’s charge if it were to gain extra electrons?
    ::问题:如果原子获得额外电子,原子的收费会怎样?

    A: If an atom were to gain extra electrons, it would have more electrons than protons. This would give it a negative charge, so it would no longer be neutral.
    ::甲:如果原子获得额外的电子,它拥有的电子比质子多。这将给它负电荷,因此它不再是中性的。

    Atoms to Ions
    ::原子到离子原子

    Atoms cannot only gain extra electrons. They can also lose electrons. In either case, they become ions . Ions are atoms that have a positive or negative charge because they have unequal numbers of protons and electrons. If atoms lose electrons, they become positive ions, or . If atoms gain electrons, they become negative ions, or . Consider the example of fluorine (see Figure ). A fluorine atom has nine protons and nine electrons, so it is electrically neutral. If a fluorine atom gains an , it becomes a fluoride ion with an electric charge of -1.
    ::原子不能只获得额外电子, 它们也可能失去电子。 无论哪种情况, 它们都可能成为离子。 离子是具有正或负电荷的原子, 因为质子和电子数量不均等。 如果原子失去电子, 它们就会变成正离子, 或者。 如果原子获得电子, 它们就会变成负离子, 或者。 以氟素为例( 见图 ) 。 氟原子有九个质子和九个电子, 所以它是中性的。 如果氟原子获得一个, 它会变成氟化离子, 电费为-1 。

    Comparison of fluorine atom and fluoride ion showing electron gain and charge change.

    Names and Symbols
    ::名称和符号编号

    Like fluoride, other negative ions usually have names ending in –ide . Positive ions, on the other hand, are just given the name followed by the word ion . For example, when a sodium atom loses an electron, it becomes a positive sodium ion. The charge of an ion is indicated by a plus (+) or minus sign (-), which is written to the right of and just above the ion’s chemical symbol . For example, the fluoride ion is represented by the symbol F - , and the sodium ion is represented by the symbol Na + . If the charge is greater than one, a number is used to indicate it. For example, iron (Fe) may lose two electrons to form an ion with a charge of plus two. This ion would be represented by the symbol Fe 2+ . This and some other common ions are listed with their symbols in the Table .
    ::类似氟化物,其他负离子通常有以-ide结尾的名称。相反,正离子只是给定名称之后的一字离子。例如,当原子钠失去电子时,它就变成了正离子。离子的电荷用加(+)或减(-)表示,该符号写在离子的右侧,并刚好高于其化学符号。例如,氟离子用符号F-表示,钠离子则用符号Na+表示。如果电荷大于1,则用数字表示。例如,铁(Fe)可能损失两个电子来组成离子,加加2。这个离子会用符号F2+表示。这个符号和其他一些普通离子在表格中加上符号。

    Some Common Ions
    Cations Anions
    Name of Ion Chemical Symbol Name of Ion Chemical Symbol
    Calcium ion Ca 2+ Chloride Cl -
    Hydrogen ion H + Fluoride F -
    Iron(II) ion Fe 2+ Bromide Br -
    Iron(III) ion Fe 3+ Oxide O 2-

    Q: How does the iron(III) ion differ from the iron(II) ion?
    ::问题:铁离子与铁离子有何不同?

    A: The iron(III) ion has a charge of +3, so it has one less electron than the iron(II) ion, which has a charge of +2.
    ::A:铁离子的电荷为+3,因此比铁离子少一个电子,后者的电荷为+2。

    Q: What is the charge of an oxide ion? How does its number of electrons compare to its number of protons?
    ::问题:氧化离子的电荷是什么?其电子数量与质子数量相比如何?

    A: An oxide ion has a charge of -2. It has two more electrons than protons.
    ::A:氧化物离子的电荷为-2,比质子多两个电子。

    How Ions Form
    ::离子形态

    The process in which an atom becomes an ion is called ionization. It may occur when atoms are exposed to high levels of radiation. The radiation may give their outer electrons enough energy to escape from the attraction of the positive nucleus . However, most ions form when atoms transfer electrons to or from other atoms or molecules. For example, sodium atoms may transfer electrons to chlorine atoms. This forms positive sodium ions (Na + ) and negative chloride ions (Cl - ).
    ::原子成为离子的过程被称为离子化过程,当原子暴露于高辐射水平时可能发生。辐射可能给它们的外部电子足够的能量以躲避正核的吸引力。然而,当原子将电子转移到其他原子或分子或从其他原子或分子中转移出来时,大多数离子形成。例如,钠原子可能将电子转移到氯原子。这形成了正态钠离子(Na+)和负氯化离子(Cl-)。

    Q: Why do you think atoms lose electrons to, or gain electrons from, other atoms?
    ::问题:为什么你认为原子会失去电子到其他原子,或者从其他原子获得电子?

    A: Atoms form ions by losing or gaining electrons because it makes them more stable and this state takes less energy to maintain. The most stable state for an atom is to have its outermost filled with the maximum possible number of electrons. In the case of such as lithium, with just one electron in the outermost energy level, a more stable state can be achieved by losing that one outer electron. In the case of such as fluorine, which has seven electrons in the outermost energy level, a more stable state can be achieved by gaining one electron and filling up the outer energy level.
    ::A: 原子通过失去或获取电子而形成离子,因为它使电子更加稳定,而这种状态需要的能量较少。对于原子来说,最稳定的状态是将其最外层的电数尽可能多地填满。对于锂等,在最外层的能源水平上只有一台电子,失去一个外部电子可以实现更稳定的状态。对于氟等,在最外层的能源水平上有七台电子,通过获得一台电子并填充外层能源水平可以实现更稳定的状态。

    Properties of Ions
    ::Ions 属性

    Ions are highly reactive, especially as . They usually react with ions of opposite charge to form neutral compounds. For example, positive sodium ions and negative chloride ions react to form the neutral sodium chloride, commonly known as table salt . This occurs because oppositely charged ions attract each other. Ions with the same charge, on the other hand, repel each other. Ions are also deflected by a magnetic field, as you saw in the opening image of the northern lights.
    ::电离子具有高度反应性, 特别是当电离子 。 它们通常与反电离子反应形成中性化合物。 例如, 正离子和负氯化离子反应形成中性氯化钠, 通常被称为桌盐。 这是因为电离子相互吸引。 反电离子相互反射, 反向反射。 电离子也受到磁场的偏转, 正如你在北光的开映像中看到的那样。

    Summary
    ::摘要

    • Atoms have equal numbers of positive protons and negative electrons, so they are neutral in electric charge.
      ::原子的正质子和负电子数量相等,因此在电荷中是中性的。
    • Atoms can gain or lose electrons and become ions, which are atoms that have a positive or negative charge because they have unequal numbers of protons and electrons.
      ::原子可能增减电子,并成为离子,这些原子具有正或负电荷,因为它们的质子和电子数量不均等。
    • The process in which an atom becomes an ion is called ionization. It may occur when atoms are exposed to high levels of radiation or when atoms transfer electrons to or from other atoms.
      ::原子成为离子的过程被称为离子化过程,当原子暴露于高辐射水平时,或者当原子将电子转移到其他原子或从其他原子转移出来时,就可能发生。
    • Ions are reactive, attracted or repulsed by other charged particles, and deflected by a magnetic field.
      ::电离子是反应性的,被其他有电粒子吸引或击退,被磁场偏转。

    Review
    ::回顾

    1. Why are atoms neutral in electric charge?
      ::为什么原子在电费方面是中性的?
    2. Define ion.
      ::定义离子。
    3. Compare and contrast cations and anions, and give an example of each.
      ::比较和对比 和阴离子, 并给出每个例子。
    4. Describe how ions form.
      ::描述电离子的形态
    5. List properties of ions.
      ::离子属性列表 。
    6. The model in the illustration below represents an atom of lithium (Li). If the lithium atom becomes an ion, which type of ion will it be, a cation or an anion? What will be the electric charge of this ion? What will the ion be named? What symbol will be used to represent it?

      Representation of a lithium atom illustrating protons, neutrons, and electrons arrangement.


      ::下面插图中的模型代表一个锂原子(Li)。如果锂原子变成一个离子,它将是哪种离子,一种电离,一种电离或阴离子?这个离子的电荷是什么?离子的名称是什么?用什么符号来代表它?