CP5.2-electrons
- 1. Section 2:Electron Arrangement in Atoms
- 2. Apply the aufbau principle, the Pauli exclusion principle, and Hund’s Rule to generate electron configurations and spin diagrams; Explain that there can be exceptions to the normal rules for electron configurations; and Draw modified Bohr diagrams for atoms
- 3. Electron’s address Energy level Sublevel Orbital Spin Need a system for electron addresses... •Your address • State • Town • Street • House
- 4. Energy levels are numbered(1, 2, 3...) Each energy level adds one more sublevel (letters) Each sublevel adds two more orbitals Energy Level Sublevels and orbitals 1 s (one orb.) 2 s (one orb.), p (three orbs.) 3 s (one orb.), p (three orbs.), d (five orbs.) 4 s (one orb.), p (three orbs.), d (five orbs.), f (seven orbs.)
- 5. Sublevels addressed by the number of their energy level and letter of sublevel ◦ Example: 1s, 2s, 2p, 3s, 3p, 3d Still two more parts to address (orbital and spin)... Electron configuration: arrangement of electrons in an atom in its ground state Orbital diagram: illustrates arrangement and spin of electrons
- 6. Aufbau principle: electrons occupy orbitals of lowest energy first Electrons (like some students) are lazy Orbitals in same sublevel are same energy
- 7. Pauli Exclusion Principle Orbital can hold maximum of two electrons ◦ (Two per seat on the bus) If two electrons in an orbital, must be opposite spins Two possible spins: up and down
- 8. Hunds Rule Orbitals in same sublevel are same energy Electrons fill orbitals of same energy so they maximize same spin Students don’t pair up in a seat until they have to
- 9. One electron for every proton Periodic table arranged by atomic number Typewriter method: start at H, read left to right, and stop at the element you’re configuring
- 10. Further down the table... La starts 4f sublevel ◦ Comes after 6s and before 5d ◦ Lu is actually 5d1 Ac starts 5f sublevel ◦ Comes after 7s and before 6d ◦ Lr is actually 6d1 Try some...
- 11. There are exceptions to the normal rules for electron configurations Based on stability Just know that they exist, not how to do them
- 12. Atom drawn with nucleus in center and one ring for each energy level Electrons drawn as dots on the rings Example: S 1s2, one ring, 2 dots 2s2, 2p6, one ring, 8 dots 3s2, 3p4, one ring, 6 dots
- 13. Group electrons by sublevels Show spins Example: S 1s2 ◦ one ring, 2 arrows paired 2s2, 2p6 ◦ one ring, 2 arrows paired (s), 6 arrows paired (p) 3s2, 3p4 ◦ One ring, two arrows paired (s) four arrows with two paired (p) 16 p 16n
- 14. Apply the aufbau principle, the Pauli exclusion principle, and Hund’s Rule to generate electron configurations and spin diagrams? Explain that there can be exceptions to the normal rules for electron configurations? Draw modified Bohr diagrams for atoms?
- 15. Page 135 & 136, 8-13