Introduction
• Chemical Bonding –
The simultaneous
(“same time”) attraction of 2 nuclei for electrons.
• Eg.
H + H  H2
***if attraction is strong enough, a bond forms.
Why does Bonding take place???
• 1.) All elements want 8 valence
electrons . . . to be like a Noble Gas.
(Octet Rule)
• 2.) To become MORE STABLE by
releasing energy!
Types of Bonding
3 Types:
1.) Ionic Bonding
2.) Covalent Bonding
3.) Metallic Bonding
Ionic Bonding
• Ionic Bonding
– Transfer (not sharing) of electrons
– Transfer from Metals  Nonmetals
– Salts = ionic compounds
• The greater the difference in
Electronegativity (E.N.), the MORE ionic!
Q.1: Which bond is more ionic . . .NaCl or KCl???
• Q.2: Which bond is the most ionic . . .
a.) KCl b.) CaCl2 c.) MgS
d.) KF
• Q.2: Which bond was the least ionic?
• HW:
Read pp.236-240. Write a ½ page Reflection.
Covalent Bonding
• Covalent Bond:
– Compound formed through the sharing of
electrons between two Nonmetals
(Nonmetal—Nonmetal)
– **Hydrogen (H) is included as a Nonmetal!
• Eg. Draw the electron-dot structure of
a.)H2 and b.)NaCl
•
H2
NaCl
•
Covalent Bonding
• Molecule – A covalently bonded
compound.
• Q: Which of the following are molecules?
a.) NaCl b.) Zn3P2
c.) CO2
d.) Al2S3
Q: Which of the above are salts?
• Q.2.: What are two differences between
an Ionic bond and a Covalent bond?
(see notes)
Types of Covalent Bonding
2 Types of Covalent Bonding:
• a.) Nonpolar Covalent Bonding
• b.) Polar Covalent Bonding
*** “Whoever is stronger (higher E.N.) controls the electrons the longest!”
Nonpolar Covalent Bonding
A.) Nonpolar Covalent Bonding: (“NO poles”)
• EQUAL sharing of electrons
(link)
• Same electronegativity
– (Therefore, same element)
Nonpolar Covalent Bonding (cont’d)
• Diatomic Molecules = 2 atoms of the same
element covalently bonded.
Eg. H2
• ***All Diatomic Molecules:
“ BrINClHOF ”
Br2 I2 N2 Cl2 H2 O2 F2
Drawing Molecules
** 1 bond = ___ electrons = ___ electron pair(s) **
Drawing Molecules (cont’d)
• Single Covalent Bond =
____electrons (___pair) are shared equally.
• Double Covalent Bond =
____electrons (____pairs) are shared equally.
• Triple Covalent Bond =
– ____ electrons (____ pairs) are shared equally.
Drawing Molecules (cont’d)
• Eg. Draw each of the following and tell if it has a
Single, Double, or Triple Covalent Bond.
**Hint: Determine how many bonds
each element can form!**
1.) F2
2.) Br2
3.) O2
4.) N2
***Nonpolar Molecular shapes = LINEAR
Linear -
Polar Covalent Bonding
Polar Covalent Bonds: (2 poles)
– UNEQUAL sharing of electrons b/t atoms with
different E.N.
– Eg. HF
H
F
(show E.N. for each)
*** δ = slight charge from unequal sharing ***
Polar Covalent Bonding (cont’d)
H
F
(show E.N. for each)
Q.1: Which has a slight (-) charge (δ-)?
Which has a slight (+) charge (δ+)?
δ- =
Polar Covalent Bonds
δ+ =
Drawing Molecules (cont’d)
Rule for covalent bonds w/ more than 2 atoms:
***Atom (element) that needs the most
electrons will be in center!***
Formula
Electron-dot
diagram
Shape
Polar or
Nonpolar?
F2
δ- =
δ+ =
HF
δ- =
δ+ =
CH4
δ- =
δ+ =
H2O
δ- =
δ+ =
H3N
(NH3)
δ- =
δ+ =
• HW a.):
– Covalent Bond packet. Answer questions
on the last sheet (Answer sheet).
• HW b.):
– Study for quiz tomorrow (Covalent
Bonding)
Formula
H2O
CO2
CCl4
PH3
(H3P)
Electron Dot
structure
Shape
Bond type
(polar or
nonpolar)
Drawing Polyatomic Ions (Table E)
• All polyatomic ions on Table E are
bonded covalently
• Follow SAME procedure for drawing
covalent molecules
• Include a.)brackets and b.)charge (add or
subtract electrons accordingly).
Formula
H 3O +
CNSO4-2
PO4-3
Electron Dot
structure
Shape
Bond type
(polar or
nonpolar)
Q.1: Label the following compounds as ionic,
covalent, or both.
Formula
NaI
CaCO3
C2H6
NaNO3
H2
Ionic, covalent, or
both?
Why?
Types of Covalent Molecules
• Review:
– 2 Types of Covalent Bonds:
a.) Polar
b.) Nonpolar
– Determined by E.N.
• 2 Types of Covalent Molecules:
a.) Polar
b.) Nonpolar
– Determined by shape (symmetrical or
asymmetrical)
Nonpolar Molecules
A.) Nonpolar Molecules:
1.) Symmetrical (equal distribution of
charges)
– Mirror image in both directions (make dotted
lines (up/down, left/right) through center.)
• Eg. Cl2, CH4, CO2
Polar Molecules
B.) Polar Molecules:
1.) Asymmetrical (unequal distribution
of charges)
– Not a complete mirror image (one direction only)
Eg. H2O, NH3, HF
Formula
Cl2
H 2O
CO2
CCl4
NH3
Electron-dot
Structure
Shape
Bond Type:
Polar or
Nonpolar
Molecule Type:
Polar or
Nonpolar
Review Questions:
• Q.1: Which of the following contains the
most polar bond?
a.) HF
b.) HCl
c.) HBr
d.) HI
Review Questions: Matching
1.) Contains an ionic bond.
A.) NaI
2.) Is nonpolar because all its bonds are
nonpolar.
B.) O2
3.) A nonpolar molecule that contains
polar bonds.
C.) NH3
4.) A polar molecule that contains polar
bonds.
D.) CO2