Bonding What exactly is a bond? Depends…Ionic or Covalent? Polar?

NON-POLAR COVALENT=> equal sharing of electron pair 0 < ∆EN < 0.4

POLAR COVALENT= unequal sharing of electron pairs, e-’s spend more time closer to one atom, 0.4 < ∆EN < 1.7

IONIC “BOND”= transfer of electrons, no physical connection to one another, atoms are held together by an electrostatic attraction, ∆EN > 1.7

No molecular dipole=> non-polar molecule

Molecular Polarity• Tutorial 1: p. 226• Figure 6: p. 228• p. 227 #1,2• HW: p. 229 #1-7ab

Molecular Dipole is present=> polar molecule

No molecular dipole=> non-polar molecule

Molecular Dipole is present=> polar molecule

Which process requires more energy?Why?

H2O(l) H2O(g)

or

2 H2O(l) 2 H2(g) + O2(g)

Intermolecular ForcesLondon force (dispersion)•due to electrostatic attraction b/w protons in one molecule and electrons of neighbouring molecules•strength α # of e-

Intermolecular Forcesdipole-dipole force•due to attraction of one dipole by surrounding dipoles•strength α molecular polarity

Intermolecular ForcesHydrogen bonding•due to attraction of a H bonded to a highly EN atom (O, N or F) in one molecule by the lone pair of e- on a highly electronegative atom of a neighbouring molecule

H2Te bp = -10°CH2Se bp = -50°CH2S bp = -80°CH2O bp = 100°C

List all IMF for each substance.

• O2(g)

• Cl2O(g)

• H2O(l)

• CH4(g)

• CH3Cl(g)

Arrange from lowest to highest bp.

• H2O

• CH4

• CH3Cl

• NH3

• CH3OH

• H2

• C3H8

Explain each statement.

• Water has a much higher bp than methane.• Bromine is a liquid at room temperature

while chlorine is a gas.• CHCl3 has a higher bp than CCl4.

Properties of Ionic and Molecular Compounds

Create a table to compare the following properties of ionic and molecular compounds. (p. 69)

• state• solubility in water• electrical conductivity as a solid• electrical conductivity in aqueous solution• melting point• boiling point

Intermolecular Forces and StatesMelting/Boiling Point

Solubility in Water

Low Conductivity of Covalent Compounds

What is conductivity?What is electricity?Are the e- free to move in covalent

bonds? Why or why not? Covalent compounds include

fats and oils Which elements form covalent

bonds? Do these usually conduct electricity?

Conductivity of Ionic CompoundsIs there an actual bond between ionic

compounds?Ionic compounds are held together by

electrostatic attractionsThe lack of physical bonds between

ions means that electricity can be conducted through ionic compounds

What types of elements form ionic compounds? Do these elements usually conduct electricity?

Properties of Liquids

Cohesive forces: • attractions b/w like

moleculesAdhesive forces:• attractions b/w unlike

molecules

Extra Practice for the Unit Test

• There are Self-Quizzes at the end of each chapter and unit which provide further practice of concepts. Answers are provided in the back of the text book. For this unit, try Chapters 1-3 and Unit 1 Self-Quizzes.

• Unit 1 Review p. 138 #4,6-16,18-20,22,23,25,26,28-31,34-42,46-50,54-56,58,62-66,71-74