1. Valence Electrons and Electron Configuration
Explaining the arrangement of electrons
08/27 & 08/28

2. Catalyst Take out your HW to be stamped.
On your Daily Work Organizer, fill in your goal for the week.
Catalyst: Describe the pictured substances.
Video Clip: Review

3. Homework Baseball
Answer the questions on a blank sheet of paper. Use your homework.
Why are the noble gases the least reactive elements?
In the electron configuration 1s2, the 1 represents the:
(a) number of protons
(b) number of electrons
(c) the energy level

4. Homework Baseball: Answers
Why are the noble gases the least reactive elements? They have a full shell of valence electrons.
In the electron configuration 1s2, the 1 represents the:
(a) number of protons
(b) number of electrons
(c) the energy level

5. Objectives SWBAT draw Lewis dot diagrams.
SWBAT write electron configurations.
SWBAT explain the octet rule and use it to predict ion formation.

6. Agenda Catalyst Electrons and Intro to Ions Mystery Elements Puzzle
Exit Ticket

7. Properties of the atom Protons determine the physical properties
The number of protons makes the element
Electrons determine the chemical properties
Only the electrons react!!!

8. Electron Energy Levels
In the electron cloud, electrons are arranged in energy levels (aka orbitals or shells).
Electrons fill the levels from the inside out.
Electrons in the outer shell form chemical bonds (react) with other atoms.

9. Write: periods tell us energy levels1 2 3 4 5 6 7
7 periods
Elements are ordered in this way because all the elements in period 1 have 1 energy level. Elements in period 2 have 2 energy levels.
Have students label periods on one side
Write: periods tell us energy levels

10. What are valence electrons??
Valence electrons are electrons on the outer shell of an atom that are available for bonding.
Valence Electrons are VERY IMPORTANT, they determine an element’s reactivity and general characteristics

11. 3 4 5 6 7 8 1 2 Write: groups tell us # valence electrons
18 groups, grouped this way because group 1 has 1 valence electron, 2 has 2 valence electrons, group 13 has 3, 14 has 4, etc
Label these on the other periodic table 1 2
Write: groups tell us # valence electrons

12. Practice: Draw the Bohr model and Lewis Dot Structure for N, O, F, Ne, Na, and Mg. Note: 1st orbital has 2 e, 2nd and 3rd orbitals have up to 8 e.
Bohr models show us all the electrons, separated by energy level (orbital).
Lewis Dot symbols show us how many valence electrons are in an atom. Li

13. Ions!
Octet Rule: When forming ions, atoms give or take electrons in order to have a full outer orbital (or shell).
They end up with the same number of electrons as the closest noble gas. This is usually 8. (Exception: Helium with 2.)

14. Think, pair, share.
How many electrons would N, O, F, Na, & Mg lose or gain to have the same number of electrons as Ne?
What ions are formed?
Example: Lithium loses 1 e to form Li+ (same # e as He)
(Work with the person next to you and write your answers under your Lewis Dot structures in your notes.)

15. Ions! Cations and Anions
Ion = an atom that has gained or lost electrons
Ions have a negative or positive charge.
Anion = ion with a negative charge.
Usually nonmetals
Ex: Cl- S2-
Cation = ion with a positive charge.
Usually metals
Ex: Be2+ Al3+

16. Think, Pair, Share
Are the ions of N, O, F, Na, and Mg cations or anions?
Label them in your notes.
Then share with your partner.
Does Ne form an ion? Why not?

17. Electron Configuration
A way to keep track of all those electrons!
Write this down:
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

18. S orbital P orbital D orbital F orbital
Within the Energy Levels, electrons are arranged in 1 or more orbitals. Label the orbitals on your periodic table.
S orbital
P orbital 1 2 3 4 5 6 7
D orbital 6 7
F orbital
© 1998 by Harcourt Brace & Company

19. Orbitals Each orbital within a level has: different energies
different shapes
Different orientation in space S p d f

20. Periodic Table & Electron Configuration
Example - Hydrogen
1s1
# e- in sublevel
1st Period
s-block

21. Periodic Table & Electron Configuration
Example - Carbon X X X X X X
1s2
2s2
2p2
2 e- in p sublevel
2nd Period
p-block

22. Short Hand Configuration
Example - Carbon X X X X X X
[He]
2s2
2p2
2nd Period
p-block

23. S 16e- 1s2 2s2 2p6 3s2 3p4 Notation Core Electrons Valence Electrons
Longhand Configuration
S 16e-
1s2
2s2
2p6
3s2
3p4
Core Electrons
(Inner orbitals)
Valence Electrons
(Outer shell)

24. Let’s Try It!
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
Practice! Write the electron configuration for the following elements:
N, O, F, Ne, Na, Mg
Write your answers under your Bohr models and Lewis Dot Structures for these elements.

25. Agenda Catalyst Electrons and Intro to Ions Mystery Elements Puzzle
Exit Ticket

26. Mystery Elements Puzzle
Work in a group of 4 at your table
Use the clues and your periodic table to match each symbol with an element.
Write down your answers on a sheet of paper.
Raise your hand when you think you have solved the puzzle.

27. Exit Ticket
Draw the Bohr model and Lewis Dot Structure for Phosphorus (P).
Write the electron configuration of P.
How many electrons will P lose or gain to form an ion? How do you know?
What ion does P form? Is it an anion or cation?
If you are done, work on HW packet.