1. Lesson 13: Electron Rules and Diagrams

2. Review El- can only absorb fixed amounts of energy [Quantum]
El- are located around the nucleus according to their E
Low E is closest the nucleus
E Levels:
el-
el-
el-

3. El- “addresses” called
El- configurations:
tell us what region of space around the nucleus we should look in order to find a certain el-

4. El- config. have two parts:
E levels and sub-levels(orbitals)
(K shell) 1s
(L shell) 2s, 2px, 2py, 2pz
(M shell) 3s, 3px, 3py, 3pz, 3d, 3d,3d, 3d, 3d
*The # tells us the E level
*The letter tells us the shape
and direction of the sub-level

5. NUCLEUS

6. Simple El- diagrams
__ __ __ __ __ __ __ __ __
1s s p s p

7. * Rule #1 [the Aufbau Principle]:
H (1 el-)
__ __ __ __ __ __ __ __ __
1s s p s p
* Rule #1 [the Aufbau Principle]:
El- fill up the orbitals one at a time, in order

8. Rule #2 [The Pauli Exclusion Principle]:
Li (3 el-)
__ __ __ __ __ __ __ __ __
1s s p s p
Rule #2 [The Pauli Exclusion Principle]:
Orbitals hold a max. of two el-
If only one el- is in an orbital, “ un-paired”
If there are two el-, “paired”
To occupy the same orbital, the 2 el- must spin in opposite directions, up and down

9. __ __ __ __ __ __ __ __ __ 1s 2s 2p 3s 3p * Rule #3 [Hund’s Rule]:
N (7 el-)
__ __ __ __ __ __ __ __ __
1s s p s p
* Rule #3 [Hund’s Rule]:
El- fill up orbitals, one at a time, so there are max. number of “unpaired” el-

10. The shape of s, p and d orbitals

11. Ex.
H has 1 el-
1s1
He has 2 el-
1s2 1s 1s

12. Li has 3 el-
1s2 2s1
Be has 4 el-
1s2 2s2 1s 2s 1s 2s

13. B has 5 el-
1s2 2s2 2p1
C has 6 el-
1s2 2s2 2p2 1s 2s 2p 1s 2s 2p

14. F
9 el-
__ __ __ __ __ __ __ __ __
1s s p s p

15. Which is following the rules?

16. “ground state” follows the rules O has 8 el- 1s2 2s2 2p2 2-6
“excited state” does not follow rules
O 8 el-
1s2 2s2 2p3 3s