1. Chemistry Holt Ms. Colclough Nov 07 Chapter 3 Atoms and Moles Section 1: Substances are made of atoms History of atomic theory: (a start) You need to know: Name, time, country, what they said about matter.

2. Kannada, 600 BCE, India. Matter made of particles

3. Democritus: 460 BCE, Greece, Matter is made of particles Atomos = indivisible "by convention bitter, by convention sweet, but in reality atoms and void"

4. Aristotle: 400 BCE, Greece, Matter is made of air, fire, earth, water (This idea lasted until about the 1850’s CE, we have remnants of it in Astrology)

5. Some Laws of matter were figured out over a long time, with lots of experimental data: Models of molecules pg 75 (study tip)  Law of definite proportions (ratios) : Percent (%) of each element, by mass (measurable) for compounds form simple whole number ratios Before they believed in particles, they had masses from lab experiments.

6.  Law of definite proportions (ratios) : Percent (%) by mass (measurable) for compounds form simple whole number ratios H2OH2O mass of H = 2 mass of O = 16 Water data mass of water = 18 %H = 2/18 x 100=11.11% %O = 16/18 x 100 = 88.9% Oxygen: Hydrogen = 88.9 : 11.1 = 8:1 8:1 is a simple whole number ratio

7. Law of conservation of mass: Remember this from chap 1, only with energy? Restate it for Mass. Models and reactions

8. Law of multiple proportions: Table 1 (page 77) 2 elements, making 2 or more compounds. Make a ratio of the masses of one element when the other element is held constant. It will ALWAYS be ratio of WHOLE numbers. This helped prove that there were particles.

9. H2O2H2O2 H2OH2O Law of multiple proportions: Table 1 (page 77) Do the math with the masses, with Water and Hydrogen Peroxide as the two compounds with the same two elements.

10. John Dalton: England, 1808 John Dalton’s atomic theory: Matter is made of particles: The five principles Page 78 atoms

11. Assignment: page 78, 1-9 due Nov 8 Check out Scilinks (online) page 74 on atomic theory