How would you represent iron sulfide with particles?

1. How would you represent iron sulfide with particles? What evidence do you have? Are other combinations possible?

2. Separation & Formation of Water Send an electric current through it Provide energy

3. Relating to Pure Substances • Provides evidence for our definition that elements are only made of one kind of atom; cannot be broken down (separated) any further • Whereas some pure substances (compounds) such as water, can be broken down in simpler substances

4. Gay-Lussac • The water demo was an example that provided Gay-Lussac with evidence for his “combining volumes” idea: Gay-Lussac’s Law of Combining Gas Volumes: • Volumes of gases in a chemical reaction are present in the ratio of small integers (T & P constant) 2H2(g) + 1 O2(g) 2H2O (g) Ratio? 2:1:2 So if 50 L of hydrogen gas reacted with 25 L of oxygen gas, how much water vapor would be produced?

5. Example Compounds

6. Avogadro • 1811, published a hypothesis stating that the volume of a gas is directly proportional to the number of molecules of the gas V= volume; k= constant; n= # of gas molecules Therefore, equal volumes of gases with same P & T contain same # of molecules • This hypothesis allows us to deduce the number of molecules that react with one another based on volumes • In the next unit, this hypothesis will enable us to determine the relative masses of elements and compounds