1. Molecule, Compound, or Both? Sodium chloride (table salt) water Oxygen Nitrous oxide (laughing gas) Ozone

2. Sulfur (S) Iron (Fe) We have represented the compound of Fe and S in a 1:1 ratio Iron kept its property of magnetism even though it was mixed with sulfur Iron lost its magnetic property since it had changed to a completely new substance: the compound iron sulfide

3. Are all compounds formed by the combination of atoms in a 1:1 ratio? What’s the formula for water? How do you know? • One of the gases is produced 2x as fast as the other gas • We can test both gases based on their properties (Hydrogen—pop ; Oxygen—relights splint) • testing for hydrogen & oxygen gas • The gas the takes up 2x as much volume in the Hoffman apparatus is hydrogen • This must mean that for every 1 molecule of water, it consists of 2 parts hydrogen and 1 part oxygen electrolysis and formation of water Positively charged Negatively charged

4. Formation of water experiment • Video we watched showed the scientists trying to combine 2 volumes of hydrogen gas with 2 volumes of oxygen gas (2:2 volume ratio) + • Notice the “extra” oxygen that was unused • Despite repeated trials, 2 volumes of hydrogen will combine with only 1 volume of oxygen • Avogadro was one of many to repeat this experiment, which provided the basis for Avogadro’s hypothesis +