Chemical bonding valence electrons electronegativity ionization energy Lewis Dot Octet Rule Types of Bonding Ionic bond Covalent Bond Metallic Bond

1. METALLIC
BOND
Bonding
Lewis
Dot
Diagram
Chemical Bonds and Metallic Bonds

2. • The force that holds atoms or ions together as
a unit.
**During a chemical reaction, it is the valence
electrons that actively take part in the
charge.
• The electrons in the lower energy levels
usually remain unchanged
Chemical Bonding

3. • Results of a chemical bonding can form
an ion, molecules and compounds
depending to what type of bonding took
place.
Chemical Bonding

4. Has two types
Ionic Bonding
Covalent Bonding
Chemical Bonding

5. Valence
electrons
Lewis Dot
Diagram
Octet
Rule
ELECTRO-
NEGATIVITY

6. How many valence
electrons are there in
Chlorine?
Valence Electrons
The number of electrons in the
outermost shell; or the outermost
electrons.
How many valence electrons
are there in Neon?
Cl- 1s2 2s2 2p6 3s2 3p5

7. ELECTRONEGATIVITY
---is a measure of the tendency of an
atom to attract electrons, the higher its
value, the higher the tendency to attract
electrons.
IONIZATION ENERGY
---is the energy needed to pull or remove
one or more electron/s from a neutral
atom. The lower the ionization energy the
easier it is remove its valence electrons.

8. METALS
---have low EN & IE, thus they tend to
TRANSFER or LOOSE electrons.
NON METALS
---have high EN & IE. They have a greater
tendency to ATTRACT electrons towards
themselves. Thus non-metals tend to GAIN
electrons.

9. WHAT KIND OF ELEMENT HAS:
• Less than 4 valence electrons?
• More than 4 valence electrons?
• Low electronegativity?
• High electronegativity?
• Low ionization energy?
• High ionization energy?

10. Lewis Dot Diagram
--Are simplified version of Bohr-Rutherford
model
The symbol of the element is written at the
center and has dots surrounding it which
represents the valence electrons.

11. Gilbert Newton Lewis
1990
An American chemist,
who developed
Lewis Dot Diagram
He contributed to the
development of the
new model of atomic
structure

12. Ways to write Lewis dot diagram
1.Write the chemical symbol of the element
2.Find the number of valence electrons
3.Draw the valence electrons using dot or
cross sign ( • or x )
H
•

13. Lewis Dot Structure of Chlorine

14. Octet Rule
Atoms tend to combine in such way that they
each have eight (8) electrons in their valence
shells, giving them the same electronic
configuration as a noble gas.
Molecules or ions tend to be stable when the
outermost electron shells contain eight
electrons.

15. Octet Rule
Happy atom – Stable – Unreactive
Unhappy atom – Unstable -- Reactive

17. An ionic bond is fomed
between a metal and a
nonmetal

18. Ionic Bond
• The transfer of electrons from one atom to another
causes electrically neutral atoms to become ions.
• The electrostatic attraction between ions of opposite charge
is called an ionic bond.
•Giving of electrons
• If the difference is greater than 1.9 EN, complete transfer of
electron/s is possible.

19. Sample problem:
Draw “dot/cross” diagrams to
represent the electron transfer
in the formation of sodium
oxide and Magnesium oxide

20. Answer:
Na and O
Na
Na
O
X X
X X
X X

21. Answer:
The Lewis structure for Na and O are:
[Na]+
[Na]+
O
X X
X X
X X[ ]
2-
Sodium Oxide (Na2O)

22. Answer:
Mg and O
Mg O
X X
X X
X X

23. Answer:
[Mg] O
X X
X X
X X
The Lewis structure for Mg and O are:
[ ]2+ 2-
Magnesium Oxide (MgO)

24. Seatwork:
In each of the following cases, the ratio in which
the ions combine is given. Show the transfer of
electrons and write the chemical formula of ionic
compounds that will be formed from them.
A. One Al and three Cl
B. One Ca and one S
C. Two Na and one O
D. One Ba and two Br
E. One Ca and two Cl

26. A covalent bond is formed
between two non metals

27. Covalent Bonds
• Covalent bonds result when two positive nuclei attract the same
electrons, thus holing the two nuclei close together.
• When two or more atoms share electrons through covalent
bonds, a single, electrically neutral unit called a molecule is
formed.
•Sharing of electrons

28. TWO TYPES OF COVALENT
• POLAR COVALENT BOND
-- If the EN difference is equal to 0.5 - 1.8
• NON POLAR COVALENT BOND
-- If the EN difference is equal to 0.4 or
less.

29. Sample problem:
Show how the NH3 was formed
after a covalent bonding.
Draw the Lewis Structure of
NH3.

30. Answer:
N and 3 H
N
H
H
H

31. Answer:
N HH
H
NH3 Nitrogen trihydride (Ammonia)

32. There are two pairs in a covalent
bond
Lone pair and Bond pair
Bond pairs
Lone pair

33. Lewis structure of
Ammonia showing
shared electrons,
showing single
bonds
Shared electrons can also be written
using a dash (-)

35. Steps to figure out if sharing of
electrons will take place
a. Get the total available valence electrons in a
compound.
b. Compute for the Octet Rule requirement that
each atom should have 8 electrons to become
stable.
c. Subtract a from b, then divide the difference by
2 because a pair of shared electron is equal to 1
bond. The quotient will give you the number of
bonds around the central atom.

36. a. Total Available VE = ( 1 C x 4) + (2 O x 6)
= ( 4 + 12) = 16
b. No. of Electrons based on Octet Rule
= ( 1 C x 8) + ( 2 O x 8 )
= 8 + 16 = 24
c.
(24 −16)
2
=
8
2
= 4

37. Seatwork:
Given the chemical formula, show the bonding of
electrons using the Lewis structure
A. H2O
B. PCl3
C. CCl4
D. SO3
E. CO2

39. Metallic Bonds
A metallic bond is pretty different from covalent and ionic
bonds, but the goal is the same: to achieve a lower energy
state. Instead of a bond between just two atoms, a metallic
bond is a sharing of electrons between many atoms of a metal
element.

40. • if you can find a small piece of metal like a paper
clip or a staple. All of the atoms in that small piece
of metal are sharing a big pool of valence
electrons known as a sea of electrons
or delocalized electrons. The big pool is like a free-
for-all in that any valence electron can move to
any atom within the material.
• Once the valence electrons detach from their
original atomic owners and float around in the
sea, the metal atoms become positive ions. The
result is an orderly structure of positive metal
atoms surrounded by a sea of negative
electrons that hold the ions together
like glue.

41. OBSERVATION EXPLANATION
Metals are dense
The particles in metals are tightly packed in
lattice.
Metals have high melting and
boiling points
Strong forces of attraction exist between
particles. A large amount of thermal energy is
required to overcome the strong electrical
forces between the positive ions and the
delocalized electrons. These forces operate
throughout the lattice
Metals are good conductors of
heat
Delocalized electrons transmit the energy of
vibrations of one positive ion to its neighbours.
Metals are good conductors of
electricity
Electrons are delocalized within the lattice.
Electrons flow in at one end and the same
number flow out the other end.
Metals are malleable and ductile
The distortion does
not
disrupt the
metallic bonding
Metals are lustrous
The presence of free electrons
causes most metals to reflect light

42. Thank you….. 