Covalent bonds form between nonmetal atoms by sharing valence electrons. Atoms share electrons to attain stable electron configurations like noble gases. Lewis structures show how valence electrons are arranged between bonded atoms. To draw Lewis structures, count the total valence electrons and distribute them to form single or double bonds between atoms until each atom has an octet of electrons. Examples of molecules held by covalent bonds are hydrogen, oxygen, and chlorine.

1. Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond
Covalent Bond

2. • Bond that is usually formed between
by
• Non-metal such as hydrogen , carbon and oxygen
do not lose electron from their outer shell .
• They do not form positive ions by losing electrons
. However their outer shells are incomplete.
• Electron need to be added to the outer shells to
attain the stability of the noble gas atoms.
• When the atoms of two non-metals react , all the
atom need to gain electrons to complete the
octet shell of electrons. They can do this by
sharing electrons between them .
sharing of electronnon-metal atoms

3. Lewis Structure
• Shows how the valence electrons of the atoms
are arranged in the molecules .
• Example
a ) A helium atom has two valence electron
*click to see
He .
.
b ) A neon atom has eight valence electrons
Ne::
. .
. .

4. • Rules for Writing Lewis Structures
i ) Add up the valence electrons of all the atom in
the molecule.
Example : CO2
: C : O O = 16 valence electrons
ii ) Use a pair of electrons to form a bond
between each pair of atoms
iii ) Arrange it like this
x x o o
xx
oo
xx
oo
O : C : O
xx
xx
xx
oo
oo
oo

5. Another
example :
Hydrogen
H H
HH Ox

6. Other molecules the are held together
by covalent bond

8. Chlorine
Molecule

9. ClCl

10. Cl Cl

11. Cl Cl

12. Cl Cl

13. Cl Cl
octet

14. Cl Cl
octet

15. Cl Cl
The octet is achieved by
each atom sharing the
electron pair in the middle

16. Cl Cl
The octet is achieved by
each atom sharing the
electron pair in the middle

17. Cl Cl
This is the bonding pair

18. Cl Cl
It is a single bonding pair

19. Cl Cl
It is called a SINGLE BOND

20. Double bond can also be shown as single
dash
Cl - Cl

21. Another example
of Single Bond

22. Double Bond
sometimes simple is better -_-

23. Oxygen

24. How will two oxygen atoms bond?
OO

25. OO
Each atom has two unpaired electrons

26. OO

27. OO

28. OO

29. OO

30. OO

31. OO

32. Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO

33. Oxygen atoms are highly electronegative.
So both atoms want to gain two electrons.
OO

34. OO

35. OO

36. OO

37. OO

38. OO
Both electron pairs are shared.

39. 6 valence electrons
plus 2 shared electrons
= full octet
OO

40. 6 valence electrons
plus 2 shared electrons
= full octet
OO

41. two bonding pairs,
OO
making a double bond

42. Double bond can also be
shown as double dashes