Smells Unit Investigation II Picturing Molecules Lesson 1

Smells Unit Investigation II: Picturing Molecules Lesson 1: Molecules in Two Dimensions Lesson 2: Honk If You Like Molecules Lesson 3: Connect the Dots Lesson 4: Eight is Enough Lesson 5: Dots, and More Dots Lesson 6: Where’s the Fun? Lesson 7: Create a Smell Lesson 8: Making Scents

Smells Unit – Investigation II Lesson 1: Molecules in Two Dimensions

Chem. Catalyst Here are drawings of two molecules that you’ve already smelled. List at least three differences and three similarities between the two molecules. Molecule #1 Molecule #2 © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • Can the structural formula of a molecule help us to predict how it will smell? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Describe a molecule based on its smell. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes • A structural formula is a drawing or diagram that a chemist uses to show the atoms in a molecule are connected. • Chemists refer to the connections between atoms in a molecule as a bond. In structural formulas, the covalent bonds are represented as lines. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: In this lesson you are introduced to the structural formulas of the molecules you have smelled plus some new molecules. You will look for patterns in the ways the atoms are connected. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • What structural features seem to be the best predictors of the smell of a molecule? © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes ketone ester carboxylic acid amine (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • Functional groups are structural features that show up repeatedly in molecules and seem to account for some of their chemical properties. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) ketone functional group ester functional group carboxylic acid functional group amine functional group © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • If a molecule is sweet, what other things do you know about it? List at least four things that are probably true. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • Structural formulas show the atoms in a molecule are put together. • Certain structural features in molecules called functional groups appear to be related to smell. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 2: Honk If You Like Molecules

Chem. Catalyst • Examine the following molecules. What patterns do you see in the bonding of hydrogen, oxygen, carbon, and nitrogen? Molecule K diisobutylamine fishy Molecule E menthone minty © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • How can HONC 1234 help us to draw structural formulas? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Determine whether the structural formula of a given molecule is possible. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes • HONC 1234 is a simple, catchy phrase reminding us about the bonding of hydrogen, oxygen, nitrogen and carbon. This easy-to-remember phrase reminds us how many bonds each element usually makes within a molecule. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • Double bonds and triple bonds still follow the HONC 1234 rule. The double-bonded oxygen in the menthone molecule is bonded twice to carbon and therefore follows the guidelines. © 2004 Key Curriculum Press. Unit 2 • Investigation II

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. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) Molecular formula #1 — C 3 H 8 Molecular formula #2 — C 3 H 8 O Molecular formula #3 — C 3 H 9 N © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • The third molecular formula has at least three possible structures. Are these all the same molecule? Explain. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes Molecular formula #1 (the same molecule drawn with two different orientations) (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) Molecular formula #2 (four different drawings are shown – three different molecules are represented) (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) Molecular formula #3 (four different drawings are shown – however, they represent only three different structures) (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • Molecules are isomers of one another if they have the same molecular formula but different structural formulas. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • Are the following molecules correct according to HONC 1234? If not, what specifically is wrong with them? 1. 2. © 2004 Key Curriculum Press. Unit 2 • Investigation II

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. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 3: Connect the Dots

Chem. Catalyst • This is a drawing of the structural formula of a methane molecule. The lines represent bonds. Explain what you think a bond is. © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • How can Lewis dot symbols help us to understand predict bonding? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Draw the Lewis dot symbol for an element and predict how many covalent bonds it will make. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes • A covalent bond is a connection that forms between two atoms when those atoms are sharing a pair of electrons between them. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • When we draw an atom using dots to represent the valence electrons it is called a Lewis dot symbol. • When we draw a molecule using dots to represent the valence electrons it is called a Lewis dot structure. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • Nitrogen, with five valence electrons, would be drawn as follows: • Notice that the Lewis dot symbol of nitrogen has three unpaired electrons and one electron pair. This means that nitrogen has three electrons that can potentially be paired up with electrons (cont. ) from other atoms. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: In this lesson you will begin to understand why atoms connect to each other the way they do. You will be introduced to a tool, called Lewis dot symbols, which will assist you in building molecules and predicting how many bonds an element will have. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) C N O F Ne Si P S Cl Ar (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) Group number IV V VI VIII First row elements C N O F Ne Second row elements Si P S Cl Ar Number of bonds (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • Based on what you’ve learned in this lesson, explain why the HONC 1234 rule works. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • Bonded pair refers to a pair of electrons that are involved in bonding between two different atoms. • Lone pair refers to a pair of electrons that are not involved in bonding but are paired up within an atom. • A single electron is sometimes referred to as an unpaired electron. lone pair of electrons bonded pair of electrons © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • Draw the Lewis dot symbol for the element I, iodine. Explain how you arrived at your particular drawing. • How many covalent bonds does iodine make? © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • A covalent bond is one in which two atoms share valence electrons. • In a Lewis dot structure, pairs of electrons that are not bonded are referred to as lone pairs. • HONC 1234 indicates how many unpaired electrons are associated with hydrogen, oxygen, nitrogen and carbon. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 4: Eight is Enough

Chem. Catalyst • Draw the Lewis dot structure for the following covalently bonded molecule. Explain how you arrived at your answer. Cl 2 © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • How can we use Lewis dot structures to help draw structural formulas? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Predict whether a given compound would be stable and likely to be found in nature. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: In this lesson you will use Lewis dot structures to create structural formulas of molecules containing elements in addition to H, O, N, and C. You will look for patterns in the number of electrons surrounding each atom in a Lewis dot structure in order to develop further understanding of bonding. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) Br 2 H 2 S PH 3 Si. H 4 (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • The noble gases do not form bonds with other atoms (except under very extreme conditions). Explain why you think this might be true (use your Lewis dot structures). © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes • Atoms of most elements are very reactive. • They become stable (the opposite of reactive) when they combine with other atoms to form compounds. • The more stable a molecule is, the more likely we are to find that it exists in nature. • The octet rule states that atoms tend to form bonds by sharing valence electrons until eight valence electrons surround each atom. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • Which of the following formulas satisfy the HONC 1234 rule? • Which of the following formulas satisfy the octet rule? • Which of the following formulas represent stable compounds we might find in the world around us? a) CH 3 b) CH 4 © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • Elements form bonds by sharing electrons until each atom has the same number of valence electrons as the noble gas in the same row of the periodic table — this is called the octet rule. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 5: Dots, and More Dots

Chem. Catalyst • Here are the structural formulas for N 2 (nitrogen gas), O 2 (oxygen gas), and F 2 (fluorine gas). Draw the Lewis dot structures for these three molecules. © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • How do we draw a Lewis dot structure for a molecule? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Use Lewis dot symbols to draw a possible structure for a C 2 H 4 O 2 molecule. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes Draw Lewis dot symbols for C and two O atoms: Bring atoms together: Create double bonds: © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: In this lesson you will work to create structural formulas for various molecules. You will start with the Lewis dot structures of individual atoms. These atoms can then be arranged in more than one way to create molecules. Finally, structural formulas will be translated from the Lewis dot representations. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) Start with these atoms… Draw the Lewis structure for the starting atoms Add hydrogen atoms to satisfy the octet rule How many H’s are needed? Draw the structural formula for the molecule Write the molecular formula for the molecule 2 carbon atoms bonded together 1 carbon atom and 1 oxygen atom 1 carbon atom and 1 nitrogen atom 1 carbon atom and 2 oxygen atoms © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • Explain how HONC 1234 assists you in checking out the structural formulas you create. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • We know two things about a certain molecule. We know that its molecular formula is C 2 H 4 O 2 and we know that it has one C=O in it. Using Lewis dot symbols and the octet rule to guide you, draw at least one possible structure for this molecule. (There a total of three possible. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • Atoms can form double and triple bonds to satisfy the octet rule. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 6: Where’s the Fun?

Chem. Catalyst The following two molecules have the same molecular formula, C 8 H 16 O 2. They also have similar properties. • How are their structural formulas similar? • How are their structural formulas different? © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes methyl heptanoate boiling point = 174 °C smell = fruity (berry) propyl pentanoate boiling point = 167. 5 °C smell = fruity (apple, pineapple) © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • How are molecular structure and molecular properties related? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Identify some common functional groups in a large molecule. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: The structure of a molecule determines its properties. Even slight changes in structure can result in significant changes in property. In this activity you will be asked to examine the relationships between the structures and properties of a specific set of molecules. From these data you should be able to predict the properties of new molecules based on their structures alone. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense 1. What kinds of molecular features did you use to predict the boiling point and smell of these five molecules? 2. What molecular features did the following molecules have in common? a)Molecules that smell fishy b)Molecules that smell putrid c) Molecules with a boiling point range of 49 -69 degrees © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes alcohol functional group alkane © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In Group the following molecules according to their smell. a. Which ones will have similar smells? b. What smells would you predict for the groups and why? (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) acetic acid butanol butyl acetate formic acid octanol © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • Molecules with the same functional groups have similar boiling points as well as similar smells. • The structural features of a molecule are largely responsible for the chemical behavior of the molecule. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 7: Create a Smell

Chem. Catalyst • What are some of the starting ingredients you will be using in this lab? • Name something you will be doing to the chemicals in this experiment. © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • How do chemists create the smells they want in the laboratory? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Determine whether two molecules with distinct smells can combine to produce a molecule with a different smell. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: You will be working in the lab to create new smells. Purpose: Today’s lesson is a formal laboratory experiment. You should have read the pre-lab and become acquainted with the experimental procedure before today’s class. You will be working in the lab to create new smells. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Safety Precautions: • Dress appropriately for a chemistry lab and always wear goggles. • There should be NO OPEN FLAMES because the organic chemicals are flammable. • Extreme care should be taken when handling 18 M sulfuric acid. It burns the skin and creates holes in clothing. • Heating must be done slowly and carefully. When heating is finished, hot plates should be turned off immediately. • During clean-up place the final products in designated waste containers. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) Test Tube Organic Acid Alcohol 1 acetic acid isoamyl alcohol 2 acetic acid butyl alcohol 3 butyric acid ethyl alcohol (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) Test Tube Smell of Organic Acid Smell of Alcohol Smell of Mixture Before Heating Smell of Mixture After Heating 1 2 3 © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • What functional group do you think is present in the final molecules? Explain. • What do you think happened to the molecules to change the smell? © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • No Check-In. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • Two molecules with distinct smells can combine to produce a new molecule(s) with a different smell. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Smells Unit – Investigation II Lesson 8: Making Scents

Chem. Catalyst • What do you think happened in yesterday’s experiment to transform an acid molecule and an alcohol molecule into a sweet smelling molecule? © 2004 Key Curriculum Press. Unit 2 • Investigation II

The Big Question • What happened in the test tubes to create new substances? © 2004 Key Curriculum Press. Unit 2 • Investigation II

You will be able to: • Predict the product of a chemical reaction. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes • A chemical reaction (rxn) is defined as a chemical transformation or change that occurs when substances interact to produce new substances with new properties. • A chemical reaction is the same as a chemical change. • The starting ingredients in a chemical reaction are called the reactants. • The ending compounds are called the products. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) • When chemists show the reactants and the products in a chemical sentence like this: A+B C+D or A+B E it is called a chemical equation. • A catalyst is a substance added to a reaction that accelerates that chemical reaction but is not itself consumed or altered by the reaction. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Activity Purpose: This lesson will assist you in processing and making sense of the experiment you just completed. By examining the structural formulas of the starting ingredients, you will be able to see how the molecules broke apart and recombined to create the sweet-smelling products. (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) acetic acid butanol (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) acetic acid butanol (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) acetic acid isoamyl alcohol isoamyl acetate (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) butyric acid ethyl alcohol ethyl butyrate (cont. ) © 2004 Key Curriculum Press. Unit 2 • Investigation II

(cont. ) formic acid octanol © 2004 Key Curriculum Press. Unit 2 • Investigation II

Making Sense • Use your own words to describe what you think happened on a molecular level to the two compounds that took part in this reaction. © 2004 Key Curriculum Press. Unit 2 • Investigation II

Notes (cont. ) acetic acid water butanol butyl acetate © 2004 Key Curriculum Press. Unit 2 • Investigation II

Check-In • Predict the structural formula of the product of the following reaction. • What is missing from the equation? • What smell would you expect? • Could you figure out the name of the product? formic acid ethyl alcohol © 2004 Key Curriculum Press. Unit 2 • Investigation II

Wrap-Up • The smell of the molecules in the ester lab changed because the reactant molecules combined to form different molecules. © 2004 Key Curriculum Press. Unit 2 • Investigation II