1. Ch. 4 - Electrons in Atoms Electron Configuration

2. You will learn three ways to describe how electrons are configured around an atom In this section of notes: – Orbital Notation – Longhand December 11

3. Orbitals Overlap Each Other

4. Electron Configuration: Arrangement of electrons in the atom A few definitions Core Electrons: Inner electrons Valence Electrons: Outer shell Core Electrons: Inner electrons Valence Electrons: Outer shell

5. Arrows Point to VALENCE electrons

6. Pauli Exclusion Principle – Each orbital can hold TWO electrons with opposite spins. – Up and down arrows are used to show opposite spins. General Rules

7. Aufbau Principle – Electrons fill the lowest energy orbitals first. – “Lazy Tenant Rule” General Rules

8. What order do they fill? ALWAYS fill in the same order 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d ETC.

9. © 1998 by Harcourt Brace & Company s p d f 12345671234567 6767 Periodic Patterns OR, read the periodic table from left to right (like a page) to find the order

10. RIGHT WRONG Hund’s Rule – Within a sublevel, place one e - per orbital before pairing them. – “Empty Bus Seat Rule” General Rules RIGHT WRONG

11. Electrons are represented by arrows Orbitals represented by boxes or lines Tips: – s always has 1 line (can hold 2 e-) – p always has 3 lines (can hold 6 e-) – d always has 5 lines (can hold 10 e-) – f always has 7 lines (can hold 14 e-) Orbital Diagram: Description

12. 8 electrons, found on 2p ____________________ 1s 2s 2p 8 electrons = 8 arrows Oxygen

13. 13 electrons, found on 3p 1s 2s 2p3s3p 13 electrons = 13 arrows Aluminum

14. 32 electrons, found on 4p 1s 2s 2p3s3p 4s 3d 4p 32 electrons = 32 arrows Germanium, Ge

15. States the energy level, sublevel of each orbital and how many electrons are in each orbital 1 s 2 Longhand Configuration Energy level Sublevel Number of electrons in orbital

16. 8 electrons, found on 2p ____________________ 1s 2s 2p 1s 2 2s 2 2p 4 Oxygen

17. 13 electrons, found on 3p 1s 2s 2p3s3p 1s 2 2s 2 2p 6 3s 2 3p 1 Aluminum

18. 32 electrons, found on 4p 1s 2s 2p3s3p 4s 3d 4p 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2 Germanium, Ge

19. Practice (p. 10), #1 Phosphorus, P Sodium, Na

20. Practice (p. 10), #2 Cl 1s 2 2s 2 2p 6 3s 2 3p 5 Te 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 4