师：同学们，今天我们学习第十三章第一节分子热运动第一课时。首先，请大家看一幅图片，这是一个孙悟空模型。细心的同学会发现，这个模型是由若干小颗粒积木拼接而成，而且这些小颗粒积木还能拼成小鸟、树木、房屋、汽车等。那大家有没有思考过，这些小颗粒积木是由什么构成的？世界上各种物质又是由什么构成的呢？在古希腊，就有人猜想，物质如同这个孙悟空模型，是由微小粒子构成。只是这些微小粒子太小，肉眼无法观察。到了19世纪，欧洲科学家观察证明，常见物质是由极其微小的粒子——分子、原子构成。比如，制作金条、金首饰的金，是由大量金原子直接构成；孕育生命的水，是由水分子构成；我们赖以生存的氧气，是由氧分子构成。这些极其微小的粒子究竟有多小呢？需要用电子显微镜来观察。接下来，请同学们看视频。
（播放视频）
“PICO instrument, which has been installed about a year ago and with its special new corrector for the chromatic operation is really a very unique machine, which really offers us new possibility. I think with its new capabilities, we consider it as the best electron microscope in the world.
Being the best electron microscope in the world, PICO was very sensitive to its surroundings. Even a person's body heat would disturb it. So PICO has to be operated remotely and safely. Isolated from humans. PICO was able to unveil the secret world of the very small.
We start our investigations at a very small magnification, which is equivalent to the highest magnification, which can actually reach with a light microscope. At this magnification, the diameter of a human hair would be about that size. And now we can, in magnification, we can go at least a factor of 1,000 higher. So now we start to see the structure. Actually, these black dots are individual gold nano particles. And now you can see the individual atoms as they appear in this individual nano particle. So we see individual atoms aligned in the structure.
It's hard to imagine just how small these dots of matter really are.”
师：从视频中，我们能感受到原子非常小。如果把分子、原子想象成球形，常见物质分子和原子的直径只有1/10,000,000,000米，也就是10的 -10次方米。假如将1000万个分子一个紧挨着一个排成一列，最多也只有一毫米长。由此可见，分子和原子非常小，构成物质的分子和原子数量极其庞大。