1. Topic: Electrons in Atoms Ground/Excited States Do Now: List the charge, number of protons, and number of electrons for: 1.Ca +2 2.Fe +3 3.F -1 4.P -3 Charge = + p + = 20 e - = 20-2=18 Charge = +3 p + = 26 e - = 26-3=23 Charge = -1 p + = 9 e - = 9+1 =10 Charge = -3 p + = 15 e - = 15+3=18

3. energy levels get closer together the farther away they are from nucleus Larger orbits can hold more electrons

4. Potential Energy More PE = Less stable energy levels get closer together the farther away they are from nucleus Larger orbits can hold more electrons

5. Bohr Model Energy absorbed when electron: – moves to higher orbit (farther from nucleus) Energy released when electron: – drops to lower orbit (closer to nucleus)

6. Ground State vs. Excited State Ground state: –Lowest energy state of atom –electrons in lowest possible energy levels Configurations in Reference Tables are ground state Excited state: –Many possible excited states for each atom –One or more electrons excited to higher energy level

7. Ground State 2-8-8 Total electrons = –2+8+8=18 So protons = 18 So atomic # = 18 ELEMENT IS Ar Excited State 2-8-7-1 Total electrons = –2+8+7+1=18 So protons = 18 So atomic # = 18 ELEMENT IS Ar p + =18 n 0 =22 p + =18 n 0 =22 2e - 8e - 2e - 7e - 1e -

8. Hydrogen jumps!

9. Bright Line Spectrum –Electrons absorb energy (EXCITED) and “jump” to a higher energy level –After a short time, they “fall” back to lower energy level, giving off a specific amount of energy in the form of a photon (light)

10. Scientists of the 19 th century quickly figured out that each element generates its own unique set of wavelengths of emissions and absorptions. Hydrogen:

11. Neon line spectra