Chapter 3- Organic Chemistry3.1 - Organic Chemistry and Alkanes

Organic chemistryo the word “organic” means of, relating to, or derived from

__________________________o organic chemistry is defined as the study of

________________________________________ _____________________ compounds containing carbon-based ions (e.g. carbonate) are not considered to be organic

compounds because they contain ___________________________o of the over 10 million chemical compounds that have been discovered, at

least 90% are carbon-based molecular compoundso the properties of organic compounds are a result of

________________________________ _________________________________ recall, covalent bonds occur when

_________________________________________ of two non-metals are _________________________

o carbon has the ______________________________________________________ of any element ____________________________

o because of its high bonding capacity, carbon atoms have the ability to form chains, rings, spheres, sheets, and tubes of almost any size

carbon can also form single, double, and triple covalent bonds

Illustrating organic compoundso Lewis dot diagrams are useful for the small and simple molecules…

but are awkward with the larger, more complex molecules found in organic chemistry.

o one way to speed up the process is to expand the molecular formula into clusters of carbons

e.g. CH3-CH2-CH2- etc… to the right are six different ways of

illustrating the compound C5H12:1 – the Lewis dot diagram2 – complete structural diagram3 – condensed structural diagram4 – expanded molecular formula5 – simplified structural diagram6 – line structural diagram

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Classifying organic compoundso in order to manage the enormous number of different organic compounds, chemists divide them

into families based what makes the compound special types of bonds

_____________ ______________ ______________

Functional groups groups of atoms with elements other than carbon and hydrogen these additional groups are responsible for the unique properties of some compound

groups Ex. ethanol CH3–CH2 –OH, has the hydroxyl functional group

(-OH) which gives the compound its physical and chemical properties, such as higher solubility, & flammability.

Alkaneso hydrocarbons are compounds containing only _______________________________________o alkanes are hydrocarbons with only ______________________carbon-to-

carbon bondso the general formula for all alkanes is CnH2n+2

as the size (and molar mass) of an alkane increases, ______________________ ______________________

bigger molecules will have ___________________________, so ____________ __________________ is needed to break them apart to change state

o All alkane names end in –aneo The prefix (beginning of the word) indicates how many carbons

are in the chain Ex. Meth = one cartbon, eth = two, prop= 3, etc… notice that the first four (the smallest ones) are gases,

the next twelve are liquids, it isn’t until the molecules get very large (C17H36) that are big enough to be solid

name formulamethane CH4(g)

ethane C2H6(g)

propane C3H8(g)

butane C4H10(g)

pentane C5H12(l)

hexane C6H14(l)

heptane C7H16(l)

octane C8H18(l)

nonane C9H20(l)

decane C10H22(l)

Naming AlkanesStep #1:

o identify the longest continuous chain of carbon atoms ( the parent chain) in the structural diagram

o Note: they may not be in a straight line, but must all be connected Example 1 Example 2

Step #2: o number the carbon atoms in the parent

chain, starting from the end ___________________ ___________________________.

Name it! The number of carbons determines what the prefix is.

Only singled bonds, means it ends in –ane

See page 9 of your data booklet for the complete list of alkanes

Step #3: o identify any branches and their

location, using a number on the parent chain.

branch names always end in –yl

the prefixes (meth = one carbon, eth = two, prop= 3, etc…) indicates how many carbons are in the branch

Example 1 Example 2

four carbons = _____________ three carbons =

__________

Example 1 Example 2

one ___________________ on the _________________ of the parent chain

= ______________________

TWO __________________ _______________ BOTH on the __________________of the parent chain

= ______________________

o if the compound has more than one of the _______ ______________________________ the number of BOTH locations is listed, and a prefix is provided

Step #4: o write the complete IUPAC name, following this format:

(number of locations) – (branch name)(parent chain)

o where there are more than one type of branch group, (some with one carbon; methyl, and others with two carbons; ethyl) the branches are named in ________________________________________ (E-thyl before M-ethyl)

Example 1 Example 2

Practice 1:o Name this compound:

Step #1: identify the longest continuous chain of carbon atoms (remember it DOESN’T have to be a straight line).

Step #2: number the carbon atoms in the parent chain, starting from the end closest to a branch to determine the name. (remember all single bonded carbon chains end in –ane)

Step #3: identify any branches and their location, using a number on the parent chain.

alphabetical order

Step #4: write the complete IUPAC name: (number of locations) – (branch name)(parent chain) in

Example Step #1: identify the longest continuous chain of carbon atoms

Step #2: number the carbon atoms in the parent chain, starting from the end closest to a branch.

10 carbon parent chain = _______________________

Step #3: identify any branches and their location, using a number on the parent chain.

* four, one carbon branches on carbon 3, 4, 4 & 6 =

_______________________

* one, two carbon branch on carbon 5 =

_______________________Step #4: write the complete IUPAC name: (number of locations) – (branch name)(parent chain) in alphabetical order

______________________________

To draw alkanes:o to draw alkanes, use the IUPAC name, starting from the BACK of the compound name:

Ex. 3-ethyl-2,4-dimethylpentane

Step #1: o identify the name of the parent chain and the corresponding number of carbon atoms:

pentane = ______ carbon parent chain draw the skeleton of the parent chain

Step #2: o identify the type of branches and position them on the appropriate carbons on the parent chain.

Ee

2,4-dimethyl = _______________________ branches on the ____________ and ________________ carbon

Draw them in!

3-ethyl = ___________________________ on the _____________ carbon

Step #3: o fill-in any unfilled bond sites with hydrogens.

Don’t add too many! Remember each carbon has a MAXIMUM bonding capacity of 4!

Try These!o Draw the complete structural diagram for:

ethane 4-propyloctane 2,2,4,5-tetramethylhexane

Remember complete structural is NOT

Science 20 – A3.1 Alkanes Worksheet 1. Complete the table below: (6 marks)

2. Name the following compounds: (12 marks)

Assignment: Practice Problems (page 110) Q. 1-4 (a & c only) 3.1 Summary (page 121) Q’s 4, 5 (a,c,e 7 g) & 6

k)

j)

f)

e)

b)

a)

3. a) Complete the table below: (6 marks)

b) Carefully examine the chemical formula for each of your answers in (a). Does

each compound have a unique chemical formula?

(1 mark)

c) Explain why the IUPAC name of a compound is a better description of the compound than the chemical formula. (1 mark)

4. Draw a condensed structural diagram for each of the following compounds.

a) 3-ethylhexane d) 3,4,5-trimethylheptane g) 3-ethyl-4,6-dimethyl-5-

hexane

2-methylbutane

2,2-dimethylpropane

2,2-dimethyl butane

2,2,3-trimethylpentane

2,2,4-trimethylpentane

propyloctane

b) 2,2-dimethylbutane e) 3,4-dimethyl-4-propylheptane

c) 3-ethyl-2-methylpentane

f) 2,4,6-trimethyloctane

3.2 - Alkenes & Alkynes

o Alkenes and alkynes are hydrocarbons with double and triple bonds hydrocarbons with _____________________________ are called _________________, and with

___________ ____________________ are called _________________. these compounds are named in a similar way to alkanes, (using prefixes to indicate the

number of carbon atoms), but their names will end in – ene and –yne.

name formulaethene C2H4(g)

propene C3H6(g)butene C4H8(g)pentene C5H10(l)hexene C6H12(l)heptene C7H14(l)octene C8H16(l)nonene C9H18(l)decene C10H20(l)

name formulaethyne C2H2(g)

propyne C3H4(g)butyne C4H6(g)pentyne C5H8(l)hexyne C6H10(l)heptyne C7H12(l)octyne C8H14(l)nonyne C9H16(l)decyne C10H18(l)

o recall the general formula for alkanes was CnH2n+2

the general formula for alkenes is CnH2n and for alkynes is CnH2n-2

Stability of organic compoundso the type of bond affects the chemical properties, such as reactivity, and physical properties, such

boiling point, melting point and solubility.o a compound will be MORE STABLE if it is _______________________

this is because it has __________________________________________________ to break during the reaction

o OR if it DOES NOT ____________________________________________________ alkenes and alkynes (double or triple bond) are ___________________________________________ this is because it has _______________________________________ are a

_______________________________ in a molecule

o MORE STABLE compounds have:

more likely to be found in _______________________

Solubilityo recall the phrase “like dissolves like”

polar solutes dissolve easily in polar solvents.o water is polar, so it easily dissolves

______________________________________________________________________ Ex. salt, hydrochloric acid or ethanol alkanes, alkenes and alkynes are NON-POLAR, so they dissolve better in a non-polar solvent

(like _______) than a polar one, such as __________________.

Practice problem:o Rank the following compounds in order of lowest to highest boiling point

pentane, butane, propane propene, propane, propyne

o Rank the following compounds in order from least to most reactive ethyne, nonane, pentene octane, heptene, octene

1 2 3 4 5

1 2 3 4 5

Naming alkenes and alkyneso Naming alkenes and alkynes is similar to naming alkanes;

using prefixes to indicate the number of carbon atoms and the ending indicates the type of bond

alkanes end in -_________ alkenes end in -_________ alkynes end in - _________

o Since the location of a multiple bond affects the chemical and physical properties of a compound the name of the compound must _________________________________________________________________

pent-1-ene indicates the double bond is located _____________________________ carbons of the parent chain

pent-2-ene indicates the double bond is located between the ___________________ carbons of the parent chain

o the rules for naming are similar to alkanes, with three additional rules:Step #1:

find the longest continuous carbon chain; this is the parent chain. Use the number of carbons to determine which prefix

for alkenes and alkynes the parent chain _____________________ _____________________

Step #2: to determine the location of the double/triple bond, the parent chain is

numbered for alkenes and alkynes you start numbering from the end ______________

__________________________ (not closest to the first branch as for alkanes)

Step #3: identify any branches and their location, using a number on the parent

chain (just like with alkanes). count from the SAME side you started numbering the bond

from branch names always end in –yl

Step #4: write the complete IUPAC name, following this format:

Example

five carbons = __________double bond = _________

Example

bond between 2 & 3 = _______________

Example

______________________ on _____________carbon = _________________________

1 2 3 4 5

(number of locations)–(branch name)(prefix of carbon chain-location of bond- suffix of parent chain)

________________________________________

Try This:o Name the following compound

Step #1: find the longest carbon chain; (with the multiple bond)

Step #2: determine the location of the double/triple bond, (always number the parent chain from the end closest to the multiple bond)

Step #3: identify any branches and their location, (same method as alkanes) Step #4: write the complete IUPAC name, (number of locations)–(branch name)(prefix of carbon chain-location of

bond- suffix of parent chain)

To draw alkenes/alkynes:o to draw alkenes and alkynes, use the same rules as you did for drawing alkanes, o use the IUPAC name, starting from the BACK of the compound name:

Ex. 2,5-dimethylhept-3-yneStep #1:

o identify the name of the parent chain, the corresponding number of carbon atoms AND the type/ location of the bond

hept- = _____ carbon parent chain, -3-yne is a ____________ bond on the ___________carbon

Draw the skeleton

Remember the maximum bonding capacity of carbon is 4… so that will affect the number of hydrogens on some of the carbons in the parent chain.

Since there are THREE bond in between the C’s and one, connecting to the rest of the chain there is NO ROOM for any hydrogens.

Step #2: o identify the type of branches and position them on the appropriate carbons on the parent chain.

2,5-dimethyl = _____________________________________ on the _____________ and ___________ carbon

Draw them in!

2,5-dimethyl hept-3-yne

7654321

2,5-dimethyl hept-3-yne

Example

five carbons = pent-double bond = - enebond between 2 & 3 Two carbon branch on third carbon = 3-ethyl

Step #3: o fill-in any unfilled bond sites with hydrogens.

Don’t add too many! Remember each carbon has a MAXIMUM bonding capacity of 4!

Isomerso Isomers are compounds containing the same number of carbons and hydrogens but in different

arrangements Isomers have ____________________________________________________________

Try these: o Draw the following isomers

pentane 2-methylbutane 2,2-dimethylpropane

What is the chemical formula for each isomer?

o if an organic compound has carbon-carbon double bonds, it is said to be ______________________. the addition of hydrogen molecules, to an unsaturated is called hydrogenation and results

in a ________________________ hydrocarbon

Name & Structure Formula

__________

__________

-di

the term saturated means “full” so think of alkanes are being “full” of hydrogens, where alkenes and alkynes ARE NOT

Hydrogenationo to become saturated, the double (or triple) bond breaks, and the hydrogen atoms

___________________________ ___ ____________________________o this reaction is called an __________________________________

there must always be enough hydrogens in an addition reaction to fill all the unbonded sites. Alkynes have triple bonds so TWO hydrogen molecules (4 hydrogens) are required to fill the

bonding sites

Halogenationo alkenes and alkynes also tend to react readily with other small diatomic molecules such as the

halogens F2 , Cl2, Br2 , & I2 Like with a hydrogen addition reaction, some of the _____________________________ once

occupied by multiple carbon-carbon bonds become filled with a halogen

Fats and Oilso The terms saturated and unsaturated are often used in combination with “fats”

animal fats and plant oils can be a good source of energy.o fatty acids (aka fats) are organic molecules made of

a long chain of carbons with a -COOH group at one end and a methyl group

at the other end

Oils Fats

o Recall that the structure of a molecule affects it physical and chemical properties

oils tend to be ________________

fats—(containing double or triple bonds)

this causes the _______ ______________________________, which is why the molecules can pack together as tightly.

This is why they tend to be _______________ at room temperature

o Fats (either manmade or from animals) tend to be _______ fats—(containing ONLY single bonds)

o this causes the molecule to straight, so they can pack tightly together.

o This is why they tend to be ______________ room temperature.

Their solid sate AND the fact that they are alkanes (containing all single bonds) mean they are ___________________

this means they have ____________________________________________

Unsaturated fatso monounsaturated fats –have _________________________ (and two fewer hydrogens than a saturated

fat)o polyunsaturated fats – have ________________________________________________________, (so even

fewer hydrogens) unsaturated fats are _________________________________ hydrocarbons with double or triple bonds are

__________________________________________________ = __________________________________________ to break down.

saturated fats are harder for your body to break down, so they stick around and cause “body fat”.

Essential Fatty Acidso essential fatty acids are fats your body can’t make, and are found only in certain food.

“omega-6” fatty acids are found in ______________________________________________________________

while these fats are important for clotting and inflammation, ________________________________ ______________

“omega-3” fatty acids are found in _______________________________________________________ these fats have the opposite effect as omega-6s – they reduce swelling and slow

blood clotting, so _________________________________________________________________

Trans fatso “Cis” and “Trans” refer to different 3D arrangements of a moleculeo “Cis” fats are naturally occurring, but can be made into “Trans” fats through a hydrogenation

the addition reaction involving hydrogen.

o Because they are synthetic, trans fats are the hardest for your body to break down, and are the worst kinds of fat.

o Trans fats are found in many processed foods and fast foods because they are in solid form, so they are

____________________________________ they are ______________________________________ that typical animal

fats

you need less trans fats to have the same effect on a food, so they qualify for a “low fat” label, even though the fats are much worse for you

o Because food manufacturers are allowed to put up to 0.5g of trans fats in their food and still label it as “trans fat free”, be sure to check ingredients labels for _____________________________________________________

Name:_________________________________

Purpose You will use a molecular kit to make models of the hydrocarbons listed in the procedure. Use the models to determine if the hydrocarbons contain only single bonds or if they contain double or triple bonds.

Materials • “molecular model kit”

Procedure

step 1: For each compound, build a model of the molecule. Use your supplies to determine whether there are enough hydrogen atoms to saturate the molecule. Note: Unsaturated molecule can only contain ONE double or triple bond

Assignment: Practice Problems (pg 129)

Q. 28 & 29 ** CAUTION! Your textbook uses the old IUPAC naming system, where the location of the bond goes BEFORE the parent chain. You must use the current method: Ex. A hydrocarbon with a double bond between the 1st and 2nd carbon: you SHOULD write hex-1-ene, your textbook writes it as 1-hexene

Practice Problems (pg 132)Q’s 31

3.2 Summary (pg 136)Q’s 3 & 4, 8 &10

Step 2: Complete the table for each molecule; (on the back side) Draw a complete structural diagram; and determine whether the molecule has only single bonds, whether it has at least one double or triple bond, and whether it is saturated or unsaturated. Since there is more than one way to construct each molecule, there are a number of possible responses for each of the structural diagrams

Analysis1.Earlier, you discovered that the general formula for an alkane was CnH2n+2. Alkanes have only single bonds

between the carbon atoms. Use an example from your chart to verify this formula. (Show your calculation)

2. Consider the compounds in your table that have a double bond. Use the chemical formula for each of these compounds to verify the general formula for a hydrocarbon with a double bond.

3. Consider the compounds in your table that have a triple bond. Use the chemical formula for each of these compounds to verify the general formula for a hydrocarbon with a triple bond.

Observation Chart:

Name: ________________________________________

Chemical Formula

Complete Structural Diagram

Alkane (single bonds)Alkene (double bonds)Alkyne (triple bonds)

Saturated or Unsaturated.

C5H12

C5H10

C5H8

C8H14

C4H10

C7H16

C6H12

C4H8

C7H12

C3H8

Purpose: You will use the “Fractional Distillation” applet on the Science 20 Textbook CD to explore the process of separating petroleum into its components.

Background: Before starting this activity, read through the procedure and the analysis to get a sense of what information you will need to record and what questions you will need to answer. This applet uses the term crude oil interchangeably with petroleum. Throughout this textbook, you can consider these two terms to mean the same thing

ProcedureWork through the applet by completing all the questions on each page

I. What can be made from a barrel of petroleum?

II. Complete the “Atmospheric Distillation Tower”, add labels to this graphic as you complete the applet.

III. In which part of the fractionating column is the temperature the lowest? Explain why this is?

IV. As the number of carbon atoms per molecule of hydrocarbon increases, the boiling point of the atoms will. Explain why?

V. Define isomer. Provide an example

VI. Can the components of petroleum be used in the gas tanks of motor vehicles?

VII. Cracking is a process used in the refining of petroleum. a. Define cracking. Provide a balanced chemical equation to illustrate its meaning.

b. Suggest why the word cracking was applied to this chemical process.

VIII. Alkylation is a process used to make 2,2,4-trimethylpentane, a key component in gasoline. a. Identify the other name for 2,2,4-trimethylpentane.

b. Describe alkylation. Use the balanced chemical equation for the production of 2,2,4-trimethylpentane to illustrate your answer.

IX. The performance rating of gasoline is improved by adding hydrocarbons that have undergone a reforming reaction.

a. Define reforming, and use a balanced chemical equation to illustrate your answer.

b. Suggest a reason why the term reforming was applied to this process.

Inquiry Questions

Use the pages 144-147 to answer questions 1-3

1. Why is it accurate to say “we were entering the Silicon Age”?

2. When a hydrocarbon molecule and an oxygen molecule react chemically, energy breaks molecular bonds of the reactants and forms the new molecular bonds of the products. How is energy involved in bonds forming and breaking during the reaction?

A. Energy is absorbed as bonds form and is absorbed as bonds break.

B. Energy is absorbed as bonds form and is released as bonds break.

C. Energy is released as bonds form and is absorbed as bonds break.

D. Energy is released as bonds form and is released as bonds break.

3. a. Write balanced chemical equations the combustion of. i. pentane

ii. 2-pentene

iii. 2,2-dimethylheptane (Hint: Use a condensed structural diagram.)

b. Which hydrocarbon molecule requires more oxygen to combust? Explain your answer.

c. Which hydrocarbon molecule produces more carbon dioxide and water vapour? Explain your answer.

d. Which hydrocarbon molecule releases more energy? Explain your answer.

Use the pages 147 & 149-151 to answer questions 4-74. Describe the steps that occur during a polymerization reaction.

5. For each starting compound, determine the complete structural diagrams for both the repeating polymer unit and a segment of the resulting polymer chain. Hint: use the answer above as a guide

6. Biodegradable polyethylene has the following structure:

Carboxyl groups are inserted into the polyethylene polymer to

A. make the polymer longer lasting

B. improve the strength of the polymer

C. improve the heat resistance of the polymer

D. make the polymer less resistant to sunlight

7. A group of students considered the following statements about the use of vehicles:

Which statement(s) explains why the use of vehicles contributes to the enhanced greenhouse effect? A. I B. I and III C. II D. III

vv

I. Vehicles release thermal energy through the exhaust system, braking system, and radiator.

II. Carbon dioxide is an emission from a vehicle’s exhaust system.

III. Carbon monoxide is an emission from a vehicle’s exhaust system.

Starting compound

Repeating polymer unit

Resulting polymer chain.

Application of polymer

Polypropylene is used to make indoor-outdoor carpeting and bottles.Polyvinylchloride (PVC) is used in plastic wrap, synthetic leather, and garden hoses. Anything describes as “vinyl”Polytetrafluoroethylene, (Teflon) is used for non-stick coatings on frying pans, cooking utensils, electrical insulation and super water resistant outerwear.