Modern Atomic Theory and the Laws That Led to It

To get an idea of the size of an atom, imagine picking up a grain of sand at a beach. That grain contains more atoms than you could count in a lifetime. In fact, the number of atoms in one sand grain far exceeds the number of grains on an entire beach. 

The exact number of naturally occurring elements Is controversial because some elements that were first discovered when they were synthesized are believed to also be present in trace amounts in nature. 

2 Early Ideas about the Building Blocks of Matter 

Recall the discussion of the scientific approach to knowledge from Chapter 1. The theory that aU matter is composed of atoms grew out of observations and laws. The three most important laws that led to the development and acceptance of the atomic theory are the law of conservation of mass, the law of definite proportions, and the law of multiple proportions. 

In 1789, as we saw in Chapter 1, Antoine Lavoisier formulated the law of conservation of mass, which states  

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