Lesson Plan

GLE Physical Science

22. Predict the kind of bond that will form between two elements based on electronic structure and electronegativity of the elements (e.g., ionic, polar, nonpolar) (PS-H-C5).

24. Describe the influence of intermolecular forces on the physical and chemical properties of covalent compounds (PS-H-C5).

Essential Questions

1. How is the bonding in molecular compounds different from the bonding in ionic compounds?

2. What factors affect molecular properties?

Objectives

1. What information does a molecular formula provide?

2. What representative units define molecular compounds and ionic compounds?

Vocabulary

u  covalent bond u  molecule u  diatomic molecule u  molecular compound u  molecular formula

Do Now 1. How many valence electrons are transferred from the nitrogen atom to potassium in the formation of the compound potassium nitride? a. 0 b. 1 c. 2 d. 3

2. Alloys are important because

a. their properties are superior to their component elements.

b. they never corrode.

c. they are less expensive to produce than their component elements.

d. their properties are a blend of their component elements.

3. Which of the following particles are free to drift in metals?

a. protons b. electrons c. neutrons d. cations

4. What is the basis of a metallic bond?

a. the attraction of metal ions to mobile electrons

b. the attraction between neutral metal atoms

c. the neutralization of protons by electrons

d. the attraction of oppositely charged ions

8.1: MOLECULAR COMPOUNDS

Molecular Compounds

1 Unlike ionic compounds, molecular compounds do not transfer electrons.

H20 N2

F2

Cl2 N2O

CO2

O2

Covalent Bond

2 A covalent bond hold atoms together and is formed by sharing of electrons between the atoms.

[Na+][Cl-]

Ionic Bonding [Na+]

Metallic Bonding

e-

e-

e-

e-

O=O Covalent Bonding

Molecule

3 A molecule is a neutral group of atoms joined together by covalent bonds.

Diatomic Molecule

4 Diatomic molecule that contains two atoms of the same element.

Example: O2, H2, N2, Cl2, etc.

Molecular Compound

5 A molecule that contains atoms of different elements is called a molecular compound.

Example: H2O, CO2, NO2, etc.

Molecular Formula

5 A molecular formula shows how many atoms of each element a substance contains.

Example:

H2O contains 2 Hydrogen atoms and 1Oxygen atom

atoms of different elements H2O

Molecular Representations

Glucose Molecule C6H12O6

Molecular Formula

Structural Formula

Ball-and-stick molecular model

Space-filling molecular model

Perspective drawings

Notes u  A covalent bond hold atoms together and is formed by sharing of

electrons between the atoms.

u  A molecule is a neutral group of atoms joined together by covalent bonds.

u  Diatomic molecule that contains two atoms of the same element.

Example: O2, H2, N2, Cl2, etc.

u  A molecule that contains atoms of different elements is called a molecular compound. Ex: H2O, CO2, NO2, etc.

u  A molecular formula shows how many atoms of each element a substance contains. Ex: H2O contains 2H and 1O atoms

Molecular v Ionic Compounds

Features Molecular Compounds Ionic Compounds

1. Composition

2. Representation

3. Physical State

4. Melting & Boiling Points

Graphic Organizer Leave at least 4 lines for each feature

Molecular compounds are mostly composed of nonmetals.

Ionic compounds are composed of a metal and a nonmetal.

Molecular v Ionic Compounds

6

Molecular v Ionic Compounds

7 Molecular compounds are represented by a molecular formula.

Ionic compounds are represented by a formula unit.

H2O

NaCl CO2

Molecular v Ionic Compounds

8 Molecular compounds tend to be gases or liquids at room temperature.

Ionic compounds tend to be solids.

Molecular Compounds Carbon dioxide gas Nitrogen gas Chlorine gas

Ionic Compounds Sodium chloride Copper sulfate Iron Oxide

Molecular v Ionic Compounds

9 Molecular compounds have lower MPs and BPs. Ionic compounds have higher MPs and BPs. MP = Melting point BP = Boiling point

Sodium chloride Solid White 801 1143

Quick Practice 1

1. Covalent compounds are formed between a. two metals. b. two metalloids.

c. a metal and a nonmetal. d. two nonmetals.

2. Covalent compounds generally tend to have a. high boiling points but low melting points.

b. low boiling points but high meting points. c. low boiling and melting points.

d. high boiling and melting points.

3. The substance CO2 is a a. molecular compound. b. ionic compound. c. diatomic molecule. d. atomic compound.

Quick Practice 2

4. The substance C2H5OH contains a. 1 atom of Carbon, 2 atoms of Hydrogen, and 5 atoms of Oxygen. b. 1 atom of Carbon, 5 atoms of Hydrogen, and 1 atoms of Oxygen. c. 2 atoms of Carbon, 6 atoms of Hydrogen, and 1 atom of Oxygen. d. 2 atoms of Carbon, 5 atoms of Hydrogen, and 1 atom of Oxygen.

5. Which of these represents a particle diagram for molecular oxygen? a.

b.

c.

d.

Quick Practice 2

Exit Ticket 1. Covalent compounds are formed between

a. two metals. b. two metalloids.

c. a metal and a nonmetal. d. two nonmetals.

2. Covalent compounds generally tend to have

a. high boiling points but low melting points. b. high boiling & melting points.

c. low boiling points but high meting points. d. low boiling & melting points.

3. The substance CO2 is a

a. molecular compound. b. ionic compound.

c. diatomic molecule. d. atomic compound.

4. The substance C2H5OH contains

a. 1 atom of Carbon, 2 atoms of Hydrogen, and 5 atoms of Oxygen.

b. 1 atom of Carbon, 5 atoms of Hydrogen, and 1 atoms of Oxygen.

c. 2 atoms of Carbon, 6 atoms of Hydrogen, and 1 atom of Oxygen.

d. 2 atoms of Carbon, 5 atoms of Hydrogen, and 1 atom of Oxygen.

5. Draw a particle diagram of molecular oxygen.

Particle Diagrams

atoms of one element

molecules of an element

atoms of different elements

molecules of different compounds

molecules of different elements

molecules of a compound