The atoms of molecules are linked together through a reaction known as chemical bonding. A chemical bond is a force that holds atoms together.

1. By Prof. Liwayway Memije-Cruz
Chemical Bonding

2. Chemical Bonding: How
do atoms combine?
What are the forces that
bind the atoms together?

3. Atoms
 Atoms consist mainly of
electrically charged particles
called electrons and protons.
Each electron has negative
charge and each proton has
a positive charge. Neutrons,
which are also present in
atoms, have no charge.
Normally, an atom contains
as many e le ctro ns as
pro to ns. The negative
charges and the positive
charges balance each other
and the atom is ne utral

4. Example
 When a hydrogen atom loses its single
electron. It becomes a positive hydrogen ion
(H+). A negative chlorine ion (Cl-) is a
chlorine atom with one additional electron.

5. Electrons in the outermost shell are
called valence electrons.

6. What is chemical bonding?
 The atoms of
molecules are
linked together
through a
reaction known
as chemical
bonding.
 A chemical bond
is a force that
holds atom

7. Chemical Bonding

8. Octet Rule
In order to acquire an inert gas configuration,
there is a need for 8 electrons to occupy the s
p distribution in the highest energy level of an
atom.
Consider the individual elements Na and Cl.
Sodium has the electronic configuration:
 Na = 1s2 2s2 2p6 3s1
And its outer shell configuration is 3s
 Cl = 1s2 2s2 2p6 3s2 3p5
And its outer shell configuration is 3p5

9.  There are three possible ways for any atom to
take in pursuit of an octet:
 1. Electrons could be given up to some other
atoms or group of atoms.
 2. Electrons could be gained from some other
atoms.
 3. Electrons could be shared between two
atoms.
 The three choices are depicted in the figure
below. Apply these choices to sodium and
chlorine.
How could Na and Cl attain the outer-shell
octet?

10. Reaction between Na and Cl

11. An example of how an atom complete its
octet and become stable.

12. Duplet and Octet of Inert Gases

13. Ionic or electrovalent bond
An ionic bond is formed in a compound
when the electrons from the outermost
shell of an atom are actually transferred
to the outermost shell of the combining
atom.

14. Covalent bond
The chemical bond in which two
atoms share a pair of electron
and form molecules is called
covalent bond.

15. Non-polar and polar covalent
bond
The bond that
results whenever
unequal sharing
occurs is called
polarcovalent
bond while equal
sharing of
electrons is called
non polarcovalent
bond.

16. Exercise
A. Classify the bond formed by the following
pairs of atoms as ionic or covalent
 Hydrogen and Oxygen
 Sodium and Chlorine
 Hydrogen and Fluorine
 Aluminum and Chlorine
 Magnesium and Bromine
 Carbon and Oxygen

17. Draw the Lewis Dot Structure of the
following compounds:
 H2
 MgF2
 CH4
 H2O