1. Bell Work 9/14/17
Complete Electron Configurations worksheet 1-4,

2. Bell Work 9/18/17
Complete Electron Configurations worksheet

3. Bell Work 9/21 Electron Dot Structures (EDS)- Find these electron dot structures
Atoms Sn Pb H Be Al Ag
Ions Na Cl Mg

4. Bell Work 9/21 Electron Dot Structures (EDS)- Find these electron dot structures
Atoms 
 Sn  
 Pb 
H 
Be  
 Al  
Ag 
Ions Na Cl Mg

5. Another Perspective on Electron Configuration
Triboluminescence – light from candy
with explanation

6. Valence Electrons Valence electrons:
Valence electrons are the electrons in the outermost principal energy level of an atom.
These are the electrons that are gained, lost, or shared in a chemical reaction.
Elements in a group or family have the same number of valence electrons.
© 2013 Pearson Education, Inc.
Chapter 3

7. Predicting Valence Electrons
For groups 1 & 2, the group number indicates the number of valence electrons.
Group 1 elements have 1 valence electron
Group 2 elements have 2 valence electrons
In general, transition metals have 2 valence e’s, silver is the exception, it has 1 valence electron
For groups 13-18, the last digit indicates the number of valence electrons.
Group 14 elements have 4 valence electrons
Group 18 elements have 8 valence electrons

8. Predicting Valence Electrons
Exception to the previous trends:
Helium only has 2 e’s, so it only has 2 valence e’s.

9. Valence Electrons of Transition Metals
Most transition metals have 2 valence electrons. Except silver
He has only 2 valence e’s He 2
Silver has only 1 valence e’

10. Valence Electrons
For the following atoms, identify the number of valence electrons:
Helium
Phosphorus
Calcium
Nickel
Bromine
Oxygen
Tin
Argon 2 5 7 6 4 8

11. Electron Dot Structures (EDS)-shows the symbol of the element with the valence e’s represented by dots.
Element symbol surrounded by a number of dots equal to the number of valence electrons 
 Sn  
 Pb 
H 
Be  
 Al  
Na 
All transition metals have 2 valence e’s, except silver which has 1 valence e’.
Zn  
Cu  
Ag 

12. Electron Dot Structures (EDS)18 1 2 13 14 15 16 17

13. Electron Dot Structures (EDS) for Ions --Use brackets
--Metals have no dots-they lose all
valence e’s when become an ion.
--Nonmetals have 8 dots-they gain
enough e’s to have a total of 8.
How do you determine the charge?

14. Learning Check A. X would be the electron dot formula for
A. X would be the electron dot formula for
1) Na 2) K 3) Al
 
B.  X  would be the electron dot formula for
1) B 2) N 3) V

15. Solution X would be the electron dot formula for 1) Na 2) K  
B  X  would be the electron dot formula
2) N

16. Electron Dot Structure (EDS)Practice
Write the electron dot structure for the following atoms:
Barium
Phosphorus
Nickel
Potassium
Silver
Argon
Aluminum

17. Ions
Ions are charged atoms (or groups of atoms) that have a positive or negative charge.
Ions = atoms that have lost or gained electrons
Formula for ion includes: symbol, sign, and number
Examles:
Na Ca I O-2

18. Positively Charged Ions = Cations
Taking away an electron from an atom gives a positive charge because there are now more protons, called a CATION
Example: Lithium
An atom of lithium will lose 1 e’ to becomes stable (isoelectronic with He)
Li > Li e’

19. Negatively Charged Ions = Anions
Adding an electron to an atom gives a negative charge because there are now more electrons, called an ANION
Example: Fluorine
An atom of fluorine will gain 1 e’ to becomes stable (isoelectronic with Ne)
F + e’ > F -1

20. Formula for Ions-symbol, charge, signMg
Mg 2+
Neutral atom
Atomic number = 12
Protons = 12
Electrons = 12
Equal protons and electrons give no charge
Positive ion
Atomic number = 12
Protons = 12
Electrons = 10
Two fewer electrons gives an overall charge of 2+

21. Isotopic Symbol for Ions
Write the isotopic symbol for a magnesium ion that has 12 protons, 10 electrons, 11 neutrons. 21

22. Noble Gases are extremely stable compared to other elements.
Noble gases have a full outer energy level- 8 e’s in the outer energy level.
Except for helium, there are 2 e’s in outer EL
For the other noble gases, there are 8 e’s in the outer EL.
When atoms react, they try to achieve the outer configuration of a noble gas-8 electrons in the outer energy level. They become isoelectronic with the nearest noble gas. 22

23. Octet Rule
In chemical reactions, atoms tend to gain, lose, or share electrons so as to have eight valence electrons. This is known as the octet rule.

24. Octet Rule
Metals lose electrons to take on the electron structure of the previous noble gas (go left on the periodic table). In doing so, they form positive ions (cations).
Nonmetals tend to gain electrons to take on the electron structure of the next noble gas (go right on the periodic table). In doing so, they form negative ions (anions).

25. Atoms Forming Stable Ions
Sodium can lose a valence electron. After doing so, its core electrons are configured like the noble gas neon.
1s2 2s2 2p6
1s2 2s2 2p6
1s2 2s2 2p63s1
Sodium ion is isoelectronic with neon = Stable Ion

26. Atoms Forming Stable Ions
Chlorine can gain an electron, and in doing so, its electron structure becomes like argon.
1s2 2s2 2p63s23p5
1s2 2s2 2p63s23p6
1s2 2s2 2p63s23p6
Chlorine is isoelectronic with argon = Stable Ion

27. Predicting Oxidation Number for Metals
For groups 1 & 2, the group number indicates the oxidation number (charge) of the ion formed.
Group 1 elements acquire a +1 charge.
Group 2 elements acquire a +2 charge.
Most transition metals acquire a +2 charge, except silver, it acquires a +1 charge. Note most TM’s can have a variety of charges.
For group 13 Metals the last digit indicates the oxidation number (charge) on the ion.
Group 13 elements acquire a +3 charge.

28. Predicting Oxidation Number for Nonmetals
For groups 15-17, determine the number of electrons needed to be like the nearest noble gases (count boxes going right)
Group 15 elements acquire a -3 charge.
Group 16 elements acquire a -2 charge
Group 17 elements acquire a -1 charge
What about group 18, the noble gases? What charge do they acquire?

29. Oxidation Number for metal and nonmetal elements+1
These occur b/c atoms want to achieve a noble gas e’-configuration. +2 +3 -3 -2 -1

30. Vocabulary Note:
The term “charge” and “oxidation number” can be used interchangeably.

31. Learning Check
Give the number of protons, neutrons, and electrons in: 41Ca +2 20
Write the formula and the EDS for the following ions:
Strontium ion
Bromine ion
Aluminum ion
Rubidium ion
Arsenic ion

32. Learning Check Draw the EDS for the following ions: Iodine ion
Beryllium ion
Nitrogen ion
Oxygen ion