章节大纲

  • An atomic bomb explosion creating a large mushroom cloud, demonstrating immense energy release.

    An atomic bomb explodes and generates a huge mushroom cloud. The tremendous released when the bomb explodes is incredibly destructive. Where does all the energy come from? The answer is the nucleus of the .  
    ::原子弹爆炸,并产生巨大的蘑菇云。当炸弹爆炸时释放出的巨大能量具有极大的破坏力。所有能量都来自何处?答案是核心。

    At the Heart of It All
    ::以一切之心为核心

    The nucleus (plural, nuclei) is a positively charged region at the center of the atom. It consists of two types of subatomic particles packed tightly together. The particles are , which have a positive electric charge , and , which are neutral in electric charge. Outside of the nucleus, an atom is mostly empty space, with orbiting negative particles called electrons whizzing through it. The Figure shows these parts of the atom.
    ::核核( 多元, 核) 是原子中心的一个正电荷区域 。 它由两种紧凑的亚原子粒子组成 。 这些粒子具有正电荷, 且在电荷中中性 。 在核外, 一个原子大部分是空的, 其轨道上的负粒子被称为电子在其中旋转。 图显示原子的这些部分 。

    The nucleus, cloud of electrons, and electron in an atom.

    Size and Mass of the Nucleus
    ::核心体的大小和质量

    The nucleus of the atom is extremely small. Its radius is only about 1/100,000 of the total radius of the atom. If an atom were the size of a football stadium, the nucleus would be about the size of a pea!
    ::原子的核心极小, 半径仅为原子半径的1/ 100 000。 如果原子的大小与足球场的大小相同, 核的大小大概是豆的大小 !

     

     

    Electrons have virtually no mass, but protons and neutrons have a lot of mass for their size. As a result, the nucleus has virtually all the mass of an atom. Given its great mass and tiny size, the nucleus is very dense. If an object the size of a penny had the same density as the nucleus of an atom, its mass would be greater than 30 million tons!
    ::电子实际上没有质量, 但质子和中子的大小却有很多质量。 因此, 核几乎拥有原子的所有质量。 由于其巨大的质量和很小的大小, 核非常稠密。 如果一个物体的大小与原子核的密度相同, 其质量将超过3000万吨 。

     

     

    Holding It All Together
    ::团结在一起

    Particles with opposite electric charges attract each other. This explains why negative electrons orbit the positive nucleus. Particles with the same electric charge repel each other. This means that the positive protons in the nucleus push apart from one another. So why doesn’t the nucleus fly apart? An even stronger force—called the strong nuclear force—holds protons and neutrons together in the nucleus.
    ::电荷相反的粒子相互吸引。 这解释了负电子绕着正核运行的原因。 同一电荷相同的粒子互相反射。 这意味着核中的正质子相互分开。 那么核为什么不分开呢? 更强大的力量 — — 所谓的强核力量 — — 将质子和中子放在核中。

     

     

    Q: Can you guess why an atomic bomb releases so much energy when it explodes?
    ::问:你能猜到为什么原子弹爆炸时会释放这么多能量吗?

    A: When an atomic bomb explodes, the nuclei of atoms undergo a process called fission, in which they split apart. This releases the huge amount of energy that was holding together subatomic particles in the nucleus.
    ::A:当原子弹爆炸时,原子核心会经历一个叫做裂变的过程,在这种过程中,它们分裂。这释放出大量能量,将亚原子粒子聚集在核中。

    Summary
    ::摘要

    • The nucleus is a small, dense region at the center of the atom. It consists of positive protons and neutral neutrons, so it has an overall positive charge.
      ::核核是原子中心的一个小而稠密的区域,由正质子和中中中子组成,因此整体呈正电荷。
    • The nucleus is just a tiny part of the atom, but it contains virtually all of the atom’s mass.
      ::核核只是原子的一小部分,但它几乎包含原子的所有质量。
    • The strong nuclear force holds together protons and neutrons in the nucleus and overcomes the electric force of repulsion between protons.
      ::强大的核力量将质子和中子聚集在核核中,克服质子之间的反向电力。

    Review
    ::回顾

    1. Describe the nucleus of the atom.
      ::描述原子的核心。
    2. Why is the nucleus positive in charge?
      ::为什么核心负责人是积极的?
    3. Explain why the nucleus is very dense.
      ::解释一下核核为什么非常稠密
    4. Outline the forces that act on particles in the nucleus.
      ::勾勒出在核粒子上作用的力量 。
    5. If you made a three-dimensional model of an atom and its nucleus, how would you represent the atom? How would you represent nucleus? Explain your choices.
      ::如果你做了一个原子及其核的三维模型, 你会如何代表原子?你如何代表核?解释你的选择。