1. Lecture 59/9/05

2. Quiz 2 1. Which of the following has the highest temperature? 30 °C 80 °F300 K 2. How many protons and neutrons does an atom of potassium-40 have?

3. 1 mole =the amount of substance that contains as many particles (atoms, molecules) as there are in 12.0 g of 12 C. THE MOLE 1 mole = 6.02214199 x 10 23 particles = Avagadro’s number

4. MOLAR MASS sum of the atomic weights of all atoms in the molecule molecular weight in grams/mole

5. 1 mol of 12 C = 12.00 g of C = 6.022 x 10 23 atoms of C 12.00 g/mol is the molar mass of 12 C 12.011 g/mol is the molar mass of carbon (taking into account all of the isotopes of C)

6. Mass to Moles

7. How many moles of Mg is represented by 0.200 g? How many atoms? Mg has a molar mass of 24.3050 g/mol. = 4.95 x 10 21 atoms Mg How many atoms in this piece of Mg?

8. Dmitri Mendeleev (mid-19 th cen) Periodic Table Lined up elements in horizontal rows with increasing atomic weight Started new rows when properties seemed similar Left space in table where he predicted new elements would be discovered

9. HGJ Moseley (1913) Discovered a method to determine atomic number Realized Periodic Table should be organized by atomic number Law of Chemical Periodicity: Properties are periodic functions of atomic #

11. Periodic Table