Joseph Proust (1754 - 1826)
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Current Atomic Model |
- He first published his Law of Definite Proportions (or Law of Constant Composition) in 1794.
- This law states that a compound is composed of exact proportions of elements by mass regardless of how the compound was created. For example, to make water there is a specific ratio of grams of hydrogen to grams of oxygen regardless of where your sample of water was found. All water has this particular proportion.
- For example, if one sample of water breaks down into 2 grams of hydrogen and 16 grams of water, then twice the amount of water would contain 4 grams of hydrogen and 32 grams of water. The proportion of hydrogen to oxygen is "definite" or fixed.