1. Ions & Lewis Dot Structures
Lesson 3.2 Ions

2. Lesson 3.2 Learning Goals SWBAT define the terms ion, cation, anion
SWBAT draw Lewis Dot Structures, in order to represent the valence electrons elements, compounds, and ions.

3. Ions Ions are: Atoms with overall charge that is not zero/ neutral
Ions can be either positively or negatively charged atoms.
Created when atoms gain or lose electrons
Written with a superscript designating charge: Ex: Mg2+, Cl-, Na+, O33-
We have discussed atoms with a “charge” and you all know how to calculate the number of electrons according to the charge.
Because we can only lose or gain ELECTRONS and ION is an atom that has gained or lost an electron

4. Positive Ions: Cations
Cations are positive (+) ions
Created when an atom loses / gives away an electron
Have more protons than electrons

5. Whole-Class Practice: Cations Ca2+
Calcium (Ca) has atomic number 20.
# protons in Ca? _______
# electrons in Ca?______
Overall charge of Ca? _______
A Ca2+ cation is formed when Ca loses two electrons.
# protons in Ca2+ ?_______
# electrons in Ca2+ ?______
Overall charge of Ca2+? _______

6. Negative Ions: Anions Anions are negative (-) ions
Created when an atom gains / steals an electron
Have less protons than electrons

7. Whole-Class Practice: Anions Cl-
Chlorine (Cl) has atomic number 17.
# protons in Cl? _______
# electrons in Cl?______
Overall charge of Cl? _______
A Cl- anion is formed when Cl gains one electron.
# protons in Cl- ?_______
# electrons in Cl- ?______
Overall charge of Cl- ? _______

9. Practice: With a partner, answer these questions
Give the ionic charge for each of the following:
A. 12 p+ and 10 e-
1) 0 2) 2+ 3) Cation or Anion?
B. 50p+ and 46 e-
1) 2+ 2) 4+ 3) Cation or Anion?
C. 15 p+ and 18e-
2) ) 3- 3) Cation or Anion?
9/30 – 1st stopped here
9/29 – 5th starts

10. More Practice: In your Notebook, answer the following questions
More Practice: In your Notebook, answer the following questions. Get your work stamped when finished!
Directions: Find the number of protons and electrons each ion has, and the overall charge of the ion. Use your periodic table to help you.
Use this model to guide you:
Ex: Cl-
# p+ = ________
# e- = ________
Overall = ____________
Practice Problems:
Na+
Br-
Be2+
O2-
Ba2+
S2-
Al3+
P3-
B3+
N3-

11. Ions & Lewis Dot Structures
Lesson 3.2B Lewis Dot Structures for Ions

12. Lesson 3.2B Learning Goals
SWBAT define the terms ion, cation, anion
SWBAT draw Lewis Dot Structures, in order to represent the valence electrons elements, compounds, and ions.

13. Valence Electrons
Valence electrons are the electrons in the outermost energy levels of an atom.
Valence electrons:
Have the most energy
Are held loosely by the nucleus
Can interact with valence electrons on other atoms to form ions or chemical bonds
Can be given away or stolen

14. Valence Electrons and the Periodic Table
Valence Electron Rule:
Groups of elements on the periodic table have the same number of valence electrons all the way down.
EXCEPT for the transition metals

16. Predicting Ionic Charges
Group 1:
Lose 1 electron to form 1+ ions H+
Li+
Na+ K+

17. Predicting Ionic Charges
Group 2:
Loses 2 electrons to form 2+ ions
Be2+
Mg2+
Ca2+
Sr2+
Ba2+

18. Predicting Ionic Charges
Group 13:
Loses 3
electrons to form
3+ ions
B3+
Al3+
Ga3+

19. Predicting Ionic Charges
Group 14:
Lose 4
electrons or gain
4 electrons?
Neither! Group 14 elements rarely form ions. They prefer to share.

20. Predicting Ionic Charges
Nitride
Group 15:
Gains 3
electrons to form
3- ions
Phosphide
P3-
As3-
Arsenide

21. Predicting Ionic Charges
Oxide
Group 16:
Gains 2
electrons to form
2- ions
S2-
Sulfide
Se2-
Selenide

22. Predicting Ionic Charges
Group 17:
Gains 1
electron to form
1- ions
F1-
Fluoride
Cl1-
Chloride
Br1-
Bromide
I1-
Iodide

23. Predicting Ionic Charges
Stable Noble gases do not form ions!
Group 18:

25. Atoms WANT 8 so they do anything for
The Octet Rule
Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 valence electrons
Atoms WANT 8 so they do anything for
8 electrons
C would like to
N would like to
O would like to
Gain 4 electrons
Gain 3 electrons
Gain 2 electrons

26. Lewis Dot Structures Diagrams that show only valence electrons
Shorthand showing information useful for chemical reactions and bonding.
Steps to Make LDS:
Determine number of valence electrons
Arrange valence electrons around elemental symbol
Follow electron pairing rule

27. Lewis Dot Structures
An atom’s valence electrons can be represented by Lewis dot notations.
1 valence e- X
2 valence e-
3 valence e-
4 valence e-
5 valence e-
6 valence e-
7 valence e-
8 valence e-

28. Lewis Dot Structures – Period 2
Lewis dot notations for the valence electrons of the elements of Period 2.
lithium Li
beryllium Be
boron B
carbon C
nitrogen N
oxygen O
fluorine F
neon Ne
worksheet

29. Independent Practice: In your notebook, draw Lewis Dot Structures for the following elementsNe  K
 Ca
 Al Li Be  B  C  N
11. All of the elements in period 4
(skip the transition metals, groups 3 – 12).