1. Electron Arrangement

2. Atoms Review
Name the three particles of the atom and their respective charges are:
a. Proton positive
b. Neutron_ neutral, no charge
c. Electron negative

3. Atoms Review The number of protons in one atom of an
element determines the atom’s
identity, and the number of electrons
determines the charge of an element.

4. Atoms Review
The atomic number tells you the number of protons in one atom of an element. It also tells you the number of electrons in a neutral atom of that element.
The atomic number gives the identity of an element as well as its location on the Periodic Table. No two elements will have the same atomic number.

5. Valence Electrons
Valence Electrons – are outer energy level electrons.
Label your periodic table with the number of valence electrons in each group. 1 8 2 3 4 5 6 7

6. X O Lewis Structures Electron Dot Diagrams Show the valence electrons
in an atom.
EX: oxygen X O

7. Lewis Structures Octet Rule
Most atoms form bonds in order to obtain _8_ valence electrons
Eight valence electrons means the atom has a full outer energy level.
A full outer energy level gives the atom stability.
Group 18, the Noble Gases have full outer energy levels.

8. Learning Check Where are the electrons in an atom located?
What number tells you the number of electrons in an atom?
What information do Lewis Dot Structures give you?
What is the octet rule?

9. Electron Configuration
Electrons in Atoms
Electron Configuration

10. Electron Configuration
The arrangement of electrons in an atom.
A distinct configuration exists for each atom.

11. Electron Configuration
Like all systems in nature, electrons in atoms tend to assume arrangements that have the lowest possible energies.
Ground State: the lowest energy arrangement of the electrons.

12. A. General Rules
Pauli Exclusion Principle
Each orbital can hold TWO electrons with opposite spins.

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

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

15. 1s2 2s2 2p4 O B. Notation 1s 2s 2p 8e- Orbital Diagram
Electron Configuration
1s2 2s2 2p4

16. S 16e- 1s2 2s2 2p6 3s2 3p4 S 16e- [Ne] 3s2 3p4 B. Notation
Longhand Configuration
S 16e-
1s2
2s2
2p6
3s2
3p4
Core Electrons
Valence Electrons
Shorthand Configuration
S 16e- [Ne] 3s2 3p4

17. C. Periodic Patterns s p d (n-1) f (n-2) 1 2 3 4 5 6 7 6 7
© 1998 by Harcourt Brace & Company

18. C. Periodic Patterns Period # energy level (subtract for d & f)
A/B Group #
total # of valence e-
Column within sublevel block
# of e- in sublevel

19. 1s1 C. Periodic Patterns 1st column of s-block 1st Period s-block
Example - Hydrogen
1s1
1st column of s-block
1st Period
s-block

20. C. Periodic Patterns p s d (n-1) f (n-2) Shorthand Configuration
Core e-: Go up one row and over to the Noble Gas.
Valence e-: On the next row, fill in the # of e- in each sublevel. s
d (n-1)
f (n-2) p

21. C. Periodic Patterns
Example - Germanium
[Ar]
4s2
3d10
4p2

22. D. Stability Full energy level Full sublevel (s, p, d, f)
Half-full sublevel

23. D. Stability Electron Configuration Exceptions Copper
EXPECT: [Ar] 4s2 3d9
ACTUALLY: [Ar] 4s1 3d10
Copper gains stability with a full d-sublevel.

24. D. Stability Electron Configuration Exceptions Chromium
EXPECT: [Ar] 4s2 3d4
ACTUALLY: [Ar] 4s1 3d5
Chromium gains stability with a half-full d-sublevel.