Covalent Bonding Table of Contents Lecture/Lab/Activity Date Pg# 22. The Periodic Table 9/24/10 47 23. Periodic Def & Trends 9/27/10 49 24. Electron config practice 10/4/10 51 25. Ions and Oxidation Numbers 10/5/10 53 26. Lewis Dot Diagram 10/6/10 54 27. Intro to Chemical Bonding 10/7/10 57 28. Covalent Bonding 10/12/10 61 Objective : The student will practice illustrating Lewis dot diagrams of covalent compounds after recording lecture notes Agenda : Covalent Bonding– Lecture
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Covalent Bonding Table of Contents Lecture/Lab/Activity Date Pg# 22. The Periodic Table9/24/10 47 23. Periodic Def & Trends9/27/10 49 24. Electron config.
Write the Lewis-e - dot structure for Nitrogen! [He]2s 2 2p 3 Electron configuration 5valence e - NNNN 5 th e - placement is arbitrary Practice Problem
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Covalent Bonding
Table of ContentsLecture/Lab/Activity Date Pg#
22. The Periodic Table 9/24/10 4723. Periodic Def & Trends 9/27/10 4924. Electron config practice 10/4/10 5125. Ions and Oxidation Numbers 10/5/10 5326. Lewis Dot Diagram 10/6/10 5427. Intro to Chemical Bonding 10/7/10 5728. Covalent Bonding 10/12/10 61
Objective:The student will practice illustrating Lewis dot diagrams of covalent compounds after recording lecture notes
Agenda:Covalent Bonding– Lecture
Valence electrons- The e- involved in chemical bonding-These e- are in the outermost “n” level- Represented by the Lewis-electron dot structure
Ex. Sulfur
[Ne]3s23p4
Electron configuration S6 valence e-
Lewis-e- dot structure
Bond Formation
Write the Lewis-e- dot structure for Nitrogen!
[He]2s22p3
Electron configuration
5valence e-
N N N N5th e- placement is arbitrary
Practice Problem
Atoms will gain, lose, or share e- until they have 8 valence e- (octet rule).
There are exceptions!Ex. He only has 2 valence e-.
Covalent bonding: Bonding in which electrons are shared instead of transferred. Occurs between non-metals
Low melting & boiling point
Covalent Bonds
Determining the # of Bonds
1. Total Needed• 8 per atom• H & He = 2
2. Total Available• Count valence electrons
3. Needed – Available = # shared
In covalent compounds, atoms share e- to achieve octets for the valence e-.
F + FF
Bonding PairEach bonding pair represents a single covalent bond.
FF = F2
Diatomic MoleculeCovalent molecule made up of 2 atoms of the same element
F
Ex. F2 formation?
Starting Valence e- = 14
Final Valence e- = 14
HH
HH
Write the Lewis-e- dot structure for CH4.
CH
C +
HH
HH C
or
H
HH
Write the Lewis-e- dot structure for PCl3.
Cl+P PCl
ClCl
PClCl
Cl
or
Cl
Cl
What about ions like ClO2-……how do
we draw the Lewis-e- dot structure???
+ O +Extra e- from the negative superscript
O OCl
or
O OCl
Cl O
Multiple BondsCovalent compounds can share more
than one pair of valence e-.
Ex. CO2
+ CO O
2 shared e- pairs = double bond
CO O
or
C OO
Example N2
N N+ NN
or
3 shared e- pairs = triple bond
NN
Write the Lewis-e- dot structure for NO2
-.
O ON + O+ ON
NO O
or
Using the concept of electronegativity, we observe that there are two types of covalent bonds.
Polar Covalent: unequal sharing of electrons by atoms that creates a small dipole.Nonpolar Covalent: equal sharing of electrons, no dipole created.