4.1 Types of Chemical Bonds

1. Types of Chemical Bonds
Chapter 4.1

2. Lewis Theory of Bonding
• Atoms and ions are stable if they
have a full valence shell of
electrons (noble gas configuration)
• Electrons are most stable when
they are paired
• Atoms form chemical bonds to
achieve a full valence shell of
electrons. This may be achieved in
two ways:
1. An exchange of electrons between
metal and non-metal atoms
2. Sharing of electrons between non-
metal atoms

3. Lewis Diagrams
• A simplified version of a Bohr-Rutherford diagram
• The chemical symbol represents the nucleus and core
electrons
• Dots around the symbol represent the valence electrons

4. Ionic Bonding
• An ionic bond is the electrostatic attraction
between oppositely charged ions
• Ionic bonds are found in ionic compounds (ex:
NaCl, Al2O3, etc.)
• Ionic bonds involve electron transfer (one atom
loses electrons and another atom gains them
• An ionic bond usually occurs between a metal
and a non-metal
• Atoms held together by ionic bonds usually have
a very high difference in electronegativity

5. Ionic Bonding

6. Crystal Lattice Structure
• In an ionic compound, ions will arrange themselves
in a crystal lattice to maximize attractions between
opposite charges and minimize repulsions between
like charges

7. Covalent Bonding
• A covalent bond is a chemical bond in which
atoms share bonding electrons
• Covalent bonds are found in molecular elements
(ex: H2, Cl2, O3) and molecular compounds (ex:
H2O, CO2 C3H8)
• A covalent bond usually occurs between two non-
metals
• There are two types of covalent bonds:
1. Non-polar covalent
2. Polar Covalent

8. Covalent Bonding

9. The Octet Rule
• Atoms tend to gain, lose, or share electrons until they are
isoelectronic with a noble gas (have the same number of
electrons as a noble gas)
• The octet rule is the observation that many atoms tend to form
the most stable substances when they are surrounded by eight
electrons in their valence shell
NOTE:
Hydrogen is an
exception. It follows the
duet rule where it shares
only one electron to
reach an outer shell of
two electrons

10. Lewis Structures
• A Lewis Structure is a diagram that shows the
arrangement of electrons and covalent bonds
in a molecule or polyatomic ion

12. Practice
• Draw the Lewis structure for sulfur trioxide

13. Practice
• Draw the Lewis structure for the chlorate ion

14. Exceptions to the Octet Rule
• Hydrogen always obeys the duet rule
• Carbon, Nitrogen, Oxygen, and Halogens often
obey the octet rule
• In all other atoms you may see exceptions to
the octet rule

15. Underfilled Octets
• Example: Boron trifluoride

16. Overfilled Octets
• Example: Sulfur hexafluoride

17. Practice
• Draw the Lewis structure for BrF5

18. Coordinate Covalent Bonding
• A coordinate covalent bond is a covalent bond
in which the electrons involved in bonding are
from one atom

19. HOMEWORK
Required Reading:
p. 192-205
(remember to supplement your notes!)
Questions:
p. 200 #1-2
p. 204 #1-2
p. 205 #1-7