Solids, Liquids, and
Intermolecular forces
Objective
•1.Learn the concepts of intermolecular
forces.
•2. Use the intermolecular forces to
explain and predict the physical
properties of substances.
Solids and Liquids
•A substance’s state of matter
depends on two factors: the
average kinetic energy of the
particles, and the intermolecular
forces between the particles.
Review: Metallic Bonds
Review: Ionic bonds
NaCl
Review: Covalent Bonds
Review: Covalent bonds:
•Polar molecule: H2O, NH3
•Nonpolar molecule: O2 , CO2 , H2
•Polarity: the dipole of a molecule.
•Dipole moment: the measure of
polarity.
Intermolecular force:
London Dispersion Forces
•It is the random polarity in a
fleeting instant in nonpolar
molecules.
•It is very weak.
•Example: gasoline, N2,CO2
Intermolecular Force: Dipole-Dipole
•The intermolecular force between polar
molecules: the positive end of one polar
molecule is attracted to the negative
end of another polar molecule.
•Example: CH3CH2OH
H2O
H2O structure
Hydrogen Bond
Hydrogen Bonding
Hydrogen Bonding Picture
Hydrogen bonds
•H is a nucleus, positive charged.
•The other extremely electronegative
elements like O, N, and F has lone pair
electrons.
•H and a electronegative element form
hydrogen bond.
•Hydrogen bond is strong.
Ice
NH3
Heating/Cooling Curve for Water
What is the strongest intermolecular force
present for each of the following compounds?
• H2O
• CH3CH3
• CH3CH2OH
• CH3CH3
• CH3OH
• CH4
• NH3
• N2,
List the substance H2 , BaCl2, Ne,
HF, and CO in order of increasing
boiling points.
CH3CH3, CH3CH2OH, CH3OH.
•What is the intermolecular forces
in each substance?
•Which has the highest boiling
point?
Learn With Technology
• http://www.chem.umass.edu/genchem/chem112/MCQ_Intermolecul
ar_Forces.htm
http://alpha.chem.umb.edu/chemistry/ch115/Mridula/CHEM%20116
/documents/chapter_11au.pdf