Modern Atomism
Idea: Do experiments and look for explanations in terms of the constituents of matter.
Chemistry: Law of Constant Proportions
- Thomas Dalton, early 19th century: chemical reactions produced substances(compounds) which were qualitatively different from the input elements which were always consumed in definite proportions.
- Idea: One “molecule” is made up of a definite number of elementary “atoms”
- Quantitative results: establish an “equivalent weight” for each element. Chemical compounds then must be formed of an integral number of the atoms of each element.
- Examples: salt: NaCl, water: H2O, glucose: C6H12O6
- Regularities allow the atoms (elements) to be grouped together in a form called the periodic table.