1. Chemical Bonding I www.chem.hawaii.edu/Bil301/welcome.html
CHEMISTRY 161
Chapter 9
Chemical Bonding I

2. THE OCTET RULE ns2np6 atoms combine to form compounds
in an attempt to obtain a stable
noble gas electron configuration
ns2np6

3. IONIC BONDING
COVALENT BONDING

4. THE OCTET RULE COVALENT BONDING sharing electrons (electron pair) F
electronic configuration of F is 1s22s22p5 F F

5. F F + F F
non-bonding, or lone pair of electrons
bonding pair of electrons

6. H2 is the simplest covalent molecule+ H H H H +
the bond length of H2 is the distance where the total energy of the molecule is minimum

7. EXAMPLES H2O NH3 CH4 HX single bonds O2 CO2 C2H4 double bonds C2H2 N2
HCN
triple bonds
transition metal compounds w/ halides
quadruple bonds

8. EXAMPLES
H2O
NH3
CH4 HX O2
CO2
C2H4
C2H2 N2
HCN

9. few thousands kJ/mol

11. IONIC OR COVALENT electronegativity difference
between the two atoms involved in the bond

12. energies of the atomic orbital with the unpaired electron
ELECTRONEGATIVITY
is the tendency of an atom in a bond to attract shared electrons to itself
F > O > N, Cl > Br > I, C, S …….. Na, Ba, Ra > K, Rb > Cs, Fr
Electronegativity increases F Cl I O N C S Na K Rb Cs Fr Ra Ba Li Br
energies of the atomic orbital with the unpaired electron

13. ELECTRONEGATIVITY F is the most electronegative
F > O > N, Cl > Br > I, C, S …….. Na, Ba, Ra > K, Rb > Cs, Fr
Electronegativity increases Li Br P I N O Cl F C S Na K Rb Cs Fr Ra Ba Se
F is the most electronegative
H has an electronegativity about the same a P

14. IONIC VERSUS COVALENT BONDS
bonds are neither completely ionic nor covalent
(only in homonuclear molecules)

15. IONIC VERSUS COVALENT BONDS
compounds composed of elements with large difference in
ELECTRONEGATIVITY
significant ionic character in their bonding
B has greater electronegativity A B

16. IONIC VERSUS COVALENT BONDS
B has a greater share A B

17. Fluorine is more electronegative than hydrogen.
HYDROGEN FLUORIDE
Fluorine is more electronegative than hydrogen. + F F H H +

18. Fluorine is more electronegative than hydrogen.
HYDROGEN FLUORIDE
Fluorine is more electronegative than hydrogen. + F F H H + d+ d–
This is a polar covalent bond.
The bond has a partly ionic and partly covalent nature.

19. Variation of ionic character with electronegativity.

20. H2O2
OF2
NF3
CO32-
NO3-
HCOOH
H2CO
CH3COOH

21. SUMMARY
IONIC BONDING
COVALENT BONDING

22. Homework
Chapter 9
pages , problem sets