A Whirlwind Introduction to Bohr Model and Quantum Mechanical Model

1. A Whirlwind Introduction to Bohr Model and Quantum Mechanical Model We’ve got a lot to do, so let’s get going!!

2. Remember Niels Bohr? • What was Bohr’s main contribution? • Planetary model of the atom • Electrons orbit the nucleus. • Each orbit (also called shells) has a specific amount of energy. • Each orbit also has a maximum number of electrons it can hold. • Electrons must be in an orbit; they cannot be inbetween.

3. How About Those Energy Levels? • Orbits labeled with whole numbers, n=1, n=2, n=3, etc. • Closer to the Nucleus = Less Energy.

4. How Much Can an Orbit Hold? Must fill up the lower-energy shells before moving outward.

5. How to Draw Bohr Models • Find number of electrons. • For a neutral (no charge) atom, atomic # = # protons = # electrons • Draw a nucleus (big dot) in the middle. • Draw circles for electron shells. • Place littledots on shells to represent electrons.

6. What Would be the Bohr Model for Al? 13 13 • Atomic # = ? • # protons = ? • # electrons = ? • Maximum numbers to fill up shells • Maximum # electrons in 1st shell? • Do you have that many to put in there? • Do you have more than that and have to keep going? • Maximum # electrons in 2nd shell? • Do you have that many to put in there? • Do you have more than that and have to keep going? • Maximum # electrons in 3rd shell? • Do you have that many to put in there? • Can you leave the very outer one partly empty? • So how many total will you put in the 3rd level? • Then draw it! 13 2 yes yes 8 yes yes 18 no yes 3

7. Isn’t It Pretty? Notice e- are in pairs except for n=1. Not necessary, but would be good to start practicing. Al

8. You Do One! • You knew that was coming, didn’t you? • Do Chlorine, Cl!

9. Check It! • Cl: atomic number = 17 = 17p+ = 17e- • 1st shell holds 2 (must keep going) • 2nd shell holds 8 (must keep going) • 3rd shell holds 18 (only have 7 to put there; it’s OK) Cl

10. Now Homework…Yay! • More practice with Bohr models!! • Don’t get excited; we’re not done!

11. I’ve Had Enough of Bohr… • Bohr’s model worked great for H, but not so great for the rest of the elements. • Quantum Mechanical Model was established and in use today! • https://www.youtube.com/watch?v=1StzvGFX4_c

12. Quantum Mechanical Model • Like Bohr’s model, electrons exist in energylevels (and not in between). • Like Bohr, the levels are labeled as whole numbers, from the inside to the outside. • Like Bohr, the lower n, the lower energy. • Unlike Bohr, QMM has electron clouds (also called orbitals) instead of orbits which show where an electron is likely to be.

13. Sounds Fascinating, Right?! • It is!! • The different electron clouds have different shapes, and there is a letter associated with each! • Get excited!!

14. Spherical shape Can hold up to 2 e- Lowest energy s orbital

15. Color in s-block Helium belongs with the s-block! 1s

16. Dumb-bell shaped Can hold up to 6 e- More energy than s orbital p orbital

17. Color in p-block Helium belongs with the s-block! 1s 1s

18. Different shapes. Can hold up to 10 e- More energy than p orbital. d orbital **Draw these 2

19. Color in d-block 1s 1s

20. Oribitals • https://www.youtube.com/watch?v=K-jNgq16jEY

21. Very odd shapes Can hold up to 14 e- Highest energy f orbital **Draw these 2

22. Color in f-block: 1s 1s Make them the same color…