Orbital Diagrams, Electron Configurations, & Valence Electrons

1. Orbital Diagrams, Electron Configurations, & Valence Electrons

3. Bohr’s Model: electrons would exist in different rings around the nucleus just like the planets are in different orbits around the sun. This is sometimes called the planetary model of the atom

4. Bohr’s Atom 7 orbits correspond to 7 periods on Periodic Table.

5. Which Orbit has the lowest energy? n = 1, the orbit closest to the nucleus.

6. Bohr’s model was replaced by the quantum mechanical model of the atom.

7. This new model uses principle quantum levels that are similar to Bohr’s orbits, but are then divided into sublevels

8. The principle quantum level is a number from 1-7, with 1 being the lowest energy and 7 being the highest in energy. The sublevels are s, p, d, and f

9. These numbers and letters correspond to the periods and the “blocks”on the periodic table.

10. Each sublevel has a least one orbital. • Each orbital can hold 2 electrons

11. The s sublevel only has 1 orbital, and each orbital holds 2 electrons Which matches the 2 elements in each period of the s block Shape: Sphere

12. The p sublevel has 3orbitals, and each orbital holds 2 electrons, for a total of 6electrons – Matching the 6 elements in each period of the p block Shape: dumbbell or peanut

13. The d sublevel has 5orbitals, and each orbital holds 2 electrons, for a total of 10 electrons – matching the 10 elements in each period of the d block Shape: clover/ double dumbbell

14. The f sublevel has 7orbitals, and each orbital holds 2 electrons, for a total of 14 electrons – matching the 14 elements Funky / flower

15. We put together the principle quantum number and sublevel letter to talk about a specific orbital But not all sublevels are possible for each energy level.

16. Principle Quantum LevelPossible Sublevels 1 s 2 s, p 3 s, p, d 4 – 7 s, p, d, f 1s 2s 2p 3s 3p 3d 4s 4p 4d 4f 5s 5p 5d 5f 6s 6p 6d (6f) 7s 7p (7d 7f)

17. The arrangement of electrons in an atom is called an orbital diagram or electronconfiguration.

18. 1) There are three rules that we must follow when making an orbital diagram (OD) or an electron configuration (EC):

19. A) The aufbauprinciple says electrons must fill lower energy levels before electrons can fill higher energy levels. This means 1s is filled before 2s, etc

20. B) The Pauliexclusion principle says that only two electrons can fill each orbital…and they must have opposite spins. NoYes

21. C) Hund’srule says electrons must spread out in the orbitals of each sublevel (p, d, or f) before they double up. Yes No □ □ □ □ □ □ 2p 2p

22. 2) If we use boxes to represent orbitals, then the following aufbau diagram shows all the possible places an electron could be:

23. Remember: s has 1 orbital…..holds 2 electrons p has 3 …..holds 6 electrons d has 5 …..holds 10 electrons f has 7 …..holds 14 electrons

24. Notice that the energy increases from bottom to top, High Energy Low Energy

25. and some of the orbitals do not fill in the same number order as the others.

26. Fill from the bottom to the top, spreading out the electrons before doubling them up

28. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Hydrogen H

29. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Helium He Completely Filled

30. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Lithium Li

31. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Beryllium Be

32. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Boron B

33. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Carbon C

34. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Nitrogen N

35. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Oxygen O

36. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Fluorine F

37. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Neon Ne Completely Filled

38. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Sodium Na

39. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Magnesium Mg

40. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Aluminum Al

41. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Silicon Si

42. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Phosphorus P

43. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Sulfur S

44. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Chlorine Cl

45. □ □ □ □ □ □ □ □ □ 3p 3s 2p 2s 1s Argon Ar Completely Filled

46. 3) The correctorder of filling is: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p Notice: s block fills in period 1 p block fills in period 2 d block fills in period 3: which is 1 behind the actual period f block fills in period 4: which is 2 behind the actual period

47. n = period # s & p block fill at n d block fills at n – 1 f block fills at n - 2

48. 4) Orbital Diagram: Orbitals are sometimes shown as boxes in a horizontal row Remember: s = 1 orbital p = 3 orbitals d = 5 orbitals f = 7 orbitals

49. 5) Arrows are used to represent the electrons, so if two arrows go in the same box, one points up and the other points down.

50. Becomes: □ □ □ □ □ 1s 2s 2p □ □ □ □ □ Nitrogen N 7 electrons 2p 2s 1s