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

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

Molecular Polarity

No molecular dipole => non-polar molecule Molecular Dipole is present => non-polar molecule Molecular Dipole is present => polar molecule

Which process requires more energy?

Why?

H 2 O (l)  H 2 O (g) or 2 H 2 O (l)  2 H 2(g) + O 2(g)

Intermolecular Forces

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

Intermolecular Forces

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

Intermolecular Forces

Hydrogen 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 H 2 Te H 2 Se H 2 S H 2 O bp = -10°C bp = -50°C bp = -80°C bp = 100°C

List all IMF for each substance.

• • • • • O 2(g) Cl 2 O (g) H 2 O (l) CH 4(g) CH 3 Cl (g)

Arrange from lowest to highest bp.

• • • • • • • H 2 O CH 4 CH 3 Cl NH 3 CH 3 OH H 2 C 3 H 8

Explain each statement.

• • • Water has a much higher bp than methane.

Bromine is a liquid at room temperature while chlorine is a gas.

CHCl 3 has a higher bp than CCl 4 .

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 States Melting/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 Compounds Is there an actual bond between ionic compounds?

Ionic compounds are held together by electrostatic attractions The 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 molecules • Adhesive 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