1. Wake-up a.Refer to element below. Name the element. b.How many protons, neutrons, and electrons? c.Naturally occurring Europium consists of two isotopes with a mass of 160 and 161. If Eu-160 has abundance 49% and Eu-161 has 145%. What is the average atomic mass of Eu?

2. Electron Configuration … Where are electrons found?

3. Electrons are important… Because they feel each other first when atoms meet. Outer electrons of atoms interact with other electrons first!

4. Neils Bohr: 1913 Electrons move in orbitals around nucleus AKA Planetary Model Each orbital holds a certain number of electrons with increasing energy

5. Electron Energy Levels 1 st Energy Level (surrounding the nucleus) contains 2 electrons 2 electrons

6. Electron Energy Levels 2 nd Energy Level (surrounding the nucleus) contains 8 electrons 8 electrons

7. Electron Energy Levels 3 rd Energy Level (surrounding the nucleus) contains 18 electrons BUT if not enough to fill 18 and enough to fill 8, fill 8 and move to next energy level. 18 electrons (8e-)

8. Electron Energy Levels 4 th Energy Level (surrounding the nucleus) contains 32 electrons 32 electrons

9. How to Complete a Bohr Ring Model Find the number of electrons; start filling the energy levels starting with the 1 st and working way out

10. Example #1: Sodium How many electrons does Sodium have? 11

11. Potassium

12. Hydrogen

13. Carbon

14. Neon

15. Calcium