Smells Unit – Investigation II

Smells Unit – Investigation II

Lesson 2:Honk If You Like Molecules

© 2004 Key Curriculum Press.

Unit 2 • Investigation II

Admit SlipHere are two examples of structural formulas of molecules.

• How many times does each hydrogen (H) bond? • How many times does each oxygen (O) bond? • How many times does each nitrogen (N) bond?

• How many times does each carbon (C) bond?



Agenda

• Admit Slip• Notes• Classwork• Exit Slip• Homework

Product: Notes, Classwork, Exit SlipHomework: Last page of packet



Today’s Objectives

Students will be able to:• Explain the HONC 1234 Rule• Draw a structural formula for a

molecule.• Determine whether the structural

formula of a given molecule is possible.



A structural formula is a 2-dimensional drawing or diagram that a chemist uses to show how the atoms in a molecule are connected.

• Chemists refer to the connections between atoms in a molecule as a covalent bond. In a covalent bond, 2 electrons are being shared.

• In structural formulas, the covalent bonds are represented as lines.

Structural Formulas / HONC 12 / 10 /12



• HONC 1234 is a phrase that helps us remember the bonding of hydrogen, oxygen, nitrogen and carbon in structural formulas.

• Hydrogen (H) forms 1 bond.• Oxygen (O) forms 2 bonds.• Nitrogen (N) forms 3 bonds.• Carbon (C) forms 4 bonds.

• Double bonds and triple bonds still follow the HONC 1234 rule. (They count as 2 or 3 bonds)



• Molecules are isomers of one another if they have the same molecular formula but different structural formulas/structures.

Notes (cont.)


Structural Formula Drawing Tips

• It is best to start with the C’s. They make up the “carbon backbone” that is goes down the middle of most molecules.

• Add in any double or triple bonds and the O’s and N’s.

• Last, add in the H’s.




Activity

Purpose: The purpose of this activity is to give you practice in creating structural formulas from molecular formulas and to help you begin to understand why atoms end up in the specific arrangements we find them in.

(cont.)



Time for Classwork!

If you finish early, work on the homework!



1. C- H- O-

2. C3H8

Classwork Review


2. This is the same molecule drawn with two

different orientations)


H

H

C CC

HH

HH

H

H

H

H

C

C

C

H

H

H

H

H

H


3. C3H8O




3. Four different drawings are possible – three different molecules (isomers) are represented)

H

H

C CC

HH

HH

H

H

OH

H

C CC

H

H

HH

H

HO

O

H

H

C CC

HH

H

H

H

H

H

CC

HH

H

H

H

O C

H

H

(cont.)


4. C3H9N




4. Four different drawings are possible – three different molecules (isomers) are represented)

H

C CC

HH

HH

H

H

N

H

H

H

C CC

HH

HH

H

H

N

H

H

H

C CC

H

H

HH

H

H

N

H

H

H

C CC

HH

H

H

H

N H

H

H

(cont.)


5. C3H6O with one C=O double bond.



6. C4H8O2 with one C=O double bond



7. C4H6O2 with two C=O double bonds.




Exit Slip

• Are the following molecules correct according to HONC 1234? If not, what specifically is wrong with them?

1. 2.H

C

H

H O H C

H

H

H

C

H

O

H

H

C

H

H



Wrap-Up

• The HONC 1234 rule tells us how many times hydrogen, oxygen, nitrogen and carbon tend to bond.

• When a molecule is oriented differently in space it is still the same molecule.

• A molecular formula can be associated with more than one distinct structural formula.

Smells Unit – Investigation II

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