SCH4C - Organic Chemistry

WHAT THE HECK IS ORGANIC CHEMISTRY?• It's the study of compounds in which carbon is the principle element, meaning,

there's a lot of carbon atoms!

LET'S MEET THE HYDROCARBONS!• Hydrocarbons are compounds containing only hydrogen and carbon atoms.• There is an enormous variety of hydrocarbons• Carbon & Hydrogen are covalently bonded. Remember what covalent bonding is? It's

atoms that are sharing electons.• Carbons join to form the backbone of the molecule with SINGLE, DOUBLE & TRIPLE

bonds.• Hydrogen bonds to each carbon to fill in wholes, because carbon needs to have a

total of 4 bonds.

SOME DEFINITIONS:

structural formula: shows full organization of bonds.

Example:

condensed formula: simplified structual formula.Example: Butane's is CH3CH2CH2CH3

molecular formula: gives symbols & subscripts.Example: Butane's is C4H10

isomer: An isomer has the same number & type atoms, but different structures.

Example:

1-butene 2-butene

By Steve Hall pg 1/3

Organic ChemistrySCH4C

Tuesday, April 23rd - Thursday,April 26th

SCH4C - Organic Chemistry

By Steve Hall pg 2/3

There are 3 different types of Hydrocarbons.

Alkanes: Carbons all have 1 bond between each other.Alkenes: There is at least 1 double bond between carbons.Alkynes: There is at least 1 triple bond between carbons.

Alkanes Alkenes AlkynesThere is only 1 bond between the There is a double bond between the There is a triple bond between these

carbons, and we know that carbons carbons. Use your hand - cover up two carbons. That fulfi lls 3/4 bonds

have 4 bonds, therefore, each the C, and 2 H's on the right side. carbon needs to make, therefore

carbon also has 3 hydrogens. See the 4 lines coming off of the C there is only 1 hydrogen hanging off

on the left side? This shows us that each carbon. It can only allow 1 to

that carbon atom has it's 4 bonds. stick on.

Prefixes SuffixesPrefixes tell us how many carbons Suffixes tell us about the carbon chain-

exist in the molecule. what type of bond exists? Is there a

branch? It also tells us what kind of

hydrocarbon we are dealing with.

1. meth- 1 carbon in molecule

2 carbons in molecule

3. prop- 3 carbons in molecule you automatically know all carbon

4. but- 4 carbons in molecule molecules have only 1 bond between them.

5. pent- 5 carbons in molecule This means a double bond exists between

6. hex- 6 carbons in molecule the carbon molecules. Our hydrocarbon

7 carbons in molecule is an alkene.

8. oct- 8 carbons in molecule This means a triple bond exists between

9. non- 9 carbons in molecule carbon molecules. Our hydrocarbon is an

10.dec- 10 carbons in molecule alkyne.

Some molecules have branches of carbon,

Molecule Names and we can easily tell which ones have

Here are some examples of what we know from branches, and where they are.

the name of a molecule we are given:

third carbon that has 1 carbon attached to it.

(3-methyl) There is a chain of 7 carbons with It consists of 3 carbons. The main chain of

is a double bond after the second carbon (2) carbons is 9-long with a double bond after C3.

eg: propane - there are 3 carbons

2. eth- 1. -ane If you see ane at the end of the name,

2. -ene

7. hept-

3. -yne

4. -yl

Butane – Has a carbon chain of 4 (but) and 3-methyl 5-heptyne – There is a branch on the 6-propyl 3-nonene – There is a carbon branch

there are only single bonds in the chain. (ane) that exists on the 6th carbon in the main chain.

2-octene – Has a carbon chain of 8 and there

a triple bond after the 5th carbon.

SCH4C - Organic Chemistry

Addition & Combustion Reactions

Addition Reactions Combustion Reactions

• Addition reactions involve alkenes and alkynes – not alkanes.

• One of the most common reactions is the combustion of hydrocarbons.

• Alkenes & alkynes are much more chemically reactive because of double & triple bonds can be broken down into single bonds.

• Remember complete combustion vs incomplete combustion? When there is enough oxygen present, hydrocarbons will react completely to form CO2 and water.

• When there are double and triple bonds, the molecule does not contain the maximum number of hydrogen atoms, making it unsaturated

• Complete combustion reactions are “clean”, meaning there are no by-products and everything has completely combusted. Incomplete combustion results in “extras left behind.”

• Alkanes are saturated because they have the maximum number of hydrogen atoms.

• If there is not enough oxygen, hydrocarbons will undergo an incomplete reaction to corm CO2, water, and two by-products, CO and C.

• Atoms or molecules can be added across double or triple bonds.

• The by-product of C (carbon) is always visible as soot, therefore it is very obvious when an incomplete combustion has happened.

Example of Addition Reaction:

H

H – C = C – H + H – H -> H – C – C – H

H

What's happening here? Two hydrogen atoms are being added to this ethene molecule. We know it is called ethene, because it's carbon chain consists of 2 carbons, (eth) and it has a double bond, making it an alkene (ene). With the addition of the two hydrogens, the double bond is broken, leaving two bonds empty, which is just enough room for the two hydrogens to stick onto the molecule. It is now saturated and is called ethane, because it is now an alkane (all single bonds).

By Steve Hall pg 3/3