Section outline

  • Model airplane demonstrating components like wings, tail, engine, and propeller.

    What is this model airplane composed of?
    ::这架模型飞机是由什么组成的?

    Millions of children over the years have enjoyed building models - this model airplane is one example of the types of models that can be constructed. Perhaps sixty years ago the models were made of balsa wood, a very light material.  Parts would be cut by hand, carefully glued together, and then covered with paper or other fabric.  The of plastics made the construction of model aircraft much simpler in many respects. And, the end-product is more durable and damage-proof.
    ::多年来,数以百万计的儿童享受了建筑模型 -- -- 这架模型飞机是可以建造模型类型的一个例子,也许在六十年前,模型是由巴萨木制成的,一种非常轻的原料。 部件将手工切割,仔细粘合在一起,然后用纸或其他纤维覆盖。 塑料使模型飞机的建造在许多方面更加简单。 最终产品更耐久,更耐受损害。

    A model serves a useful purpose – it gives us an idea of what the real thing is like.  The model plane seen above has wings, a tail, and an engine just like the real thing.  This model also has a propeller, as is the case with most small planes and some smaller passenger planes.  However, the model is not the real thing.  We certainly cannot fly people or cargo in the model (besides maybe a tiny mouse), but we can get some idea of what a real plane looks like and how it works.
    ::模型可以起到有益的作用 — — 它让我们知道真正的是什么样子。 上面看到的模型飞机有翅膀、尾巴和引擎,就像真的一样。 这个模型也有螺旋桨,就像大多数小飞机和一些小客机一样。 但是,模型不是真实的。 我们当然不能在模型中载运人或货物(也许还有一只小老鼠 ) , 但我们可以知道真正的飞机长什么样和如何运作。

    Science uses many models to explain ideas.  We model the as a very small particle with a negative charge.  That gives us a picture, but a very incomplete one.  This picture works fine for most chemists, but is inadequate for a physicist.  Models give us a start toward understanding structures and processes, but certainly are not a complete representation of the entity we are examining.
    ::科学用许多模型来解释想法。 我们用一个非常小的粒子来模拟一个负电荷。 这给了我们一个图片,但是一个非常不完整的图片。 这张照片对大多数化学家来说是不错的,但对物理学家来说是不足够的。 模型让我们开始理解结构和过程,但肯定不是我们所研究的实体的完整代表。

    Atomic Models
    ::原子模型

    The was discovered by J.J. Thomson in 1897. The existence of was also known, as was the fact that atoms were neutral in charge.  Since the intact had no net charge and the and had opposite charges, the next step after the discovery of subatomic particles was to figure out how these particles were arranged in the . This is a difficult task because of the incredibly small size of the . Therefore, scientists set out to design a model of what they believed the atom could look like. The goal of each atomic model was to accurately represent all of the experimental evidence about atoms in the simplest way possible.
    ::J.J.Thomson于1897年发现了这个粒子。同样众所周知,原子是中立的。由于完好无损的原子没有净电荷,并且有相反的电荷,亚原子粒子发现后的下一步是弄清楚这些粒子是如何排列的。由于这个粒子的大小非常小,这是一项艰巨的任务。因此,科学家们开始设计一个他们认为原子看起来像原子的模型。每个原子模型的目标是以尽可能简单的方式准确代表关于原子的所有实验证据。

    Following the discovery of the , J.J. Thomson developed what became known as the " plum pudding " model in 1904. Plum pudding is an English dessert similar to a blueberry muffin. In Thomson's plum pudding model of the , the electrons were embedded in a uniform sphere of positive charge like blueberries stuck into a muffin. The positive matter was thought to be jelly- like or a thick soup. The electrons were somewhat mobile.  As they got closer to the outer portion of the , the positive charge in the region was greater than the neighboring negative charges and the would be pulled back more toward the center region of the atom.
    ::发现后,J.J.汤姆森于1904年开发了被称为“布丁”的模型。布丁是英国甜点,类似于蓝莓松饼。在汤姆森的梅布丁模型中,电子被嵌入一个呈阳性的球体中,如夹在松饼中的蓝莓。积极物质被认为是果冻或浓汤。电子是移动的。当它们接近外部部分时,该区域正电荷大于相邻的负电荷,并将被拉回原子中心区域。

    the plum pudding model with electrons in a positive sphere.
    The "plum pudding" model.

    However, this model of the atom soon gave way to a new model developed by New Zealander Ernest Rutherford (1871-1937) about five years later.  Thomson did still receive many honors during his lifetime, including being awarded the Nobel Prize in Physics in 1906 and a knighthood in 1908.
    ::然而,这种原子模式很快就被新西兰人欧内斯特·卢瑟福(1871-1937年)在大约五年后开发的新模式所取代。 汤姆森在其一生中仍然获得许多荣誉,包括1906年获得诺贝尔物理奖和1908年获得骑士资格。

     

    Summary  
    ::摘要

    • A model gives an idea of what something looks like, but is not the real thing.
      ::模型给人一个概念 东西看起来像什么, 但不是真实的东西。
    • The "plum pudding" model of the atom consisted of a uniform sphere of positive charge with negative electrons embedded in the sphere.
      ::原子的“棉布布丁”模型 包括一个统一的正电荷范围 与球体内嵌入的负电子呈阳性电荷。

    Review
    ::回顾

    1. What is a model?
      ::什么是模型?
    2. Why are models useful in science?
      ::为什么模型在科学方面有用?
    3. In Thomson's model of the atom, where were the electrons?
      ::在汤姆森的原子模型, 电子在哪里?
    4. What was the positive charge in this model?
      ::这一模式的积极责任是什么?
    5. What kept the electrons in the atom?
      ::是什么把电子留在原子里?
    6. Whose model replaced Thomson's?
      ::谁的模型取代汤姆森的?
    7. What awards did Thomson receive?
      ::汤姆森获得什么奖项?