1. Atomic Mass Agenda Review (whiteboards) Read 4.7 & 4.8 Notes Homework

2. Parts of Atomic Theory

3. How do isotopes differ?

4. How do ions differ?

5. 14 6 C ____ p + ____ e - ____ n o

6. 9 4 Be +2 ____ p + ____ e - ____ n o

7. 36 17 Cl - ____ p + ____ e - ____ n o

8. READ Grab book Read section 4.7 & 4.8 w/ partner Six inch voices

9. Average Atomic Mass date

10. Average atomic mass A WEIGHTED average dependent on the percent abundance of each isotope. If all isotopes were in a bag, how frequently would you pull out each separate isotope. Measured in amu’s

11. Atomic Mass Unit An amu is the mass of a single proton. 1 amu = 1.67*10 -24 g

12. Determining Average Mass Multiply Mass number by Percent abundance. Add the answers. Answer should be close to most abundant isotope.

13. Example Cesium is 75% 133 Cs, 20% 132 Cs, 5% 134 Cs. What is the average atomic mass?

14. Example Chromium has four istopes. 4.35% 50 Cr, 83.79% 52 Cr, 9.5% 53 Cr, 2.36% 54 Cr. What is the average atomic mass of Cr?

15. Determining % abundance Create an equation equaling average atomic mass Mass 1 * %X + Mass2 * %Y = average atomic mass Create an equation equaling 100% X + Y = 1 Use substitution to solve for x. Mass 1 * %X + Mass2 * %(1-X) = average atomic mass

16. The average atomic weight of boron is 10.812amu. Boron has two isotopes: boron-10 with a mass of 10.013 and boron-11 with a mass of 11.009. What are the % abundances of each isotope?

17. What are the % abundances of the two isotopes of rubidium? Rb-85, 84.9918 amu Rb-87, 86.9092 amu

18. Homework Complete isotopes and average atomic mass worksheet Review scientists and discoveries. Lab report due Rough draft Wednesday Final draft Friday