KETONES & ALDEHYDES (April 28th, 2011)

Today we learned about the awesome world of KETONES & ALDEHYDES

• A ketone is a hydrocarbon chain with a double bonded oxygen that is NOT on either end! (I repeat, the double bonded oxygens are not on the end, rather, are in the middle!
• An Aldehyde is a compound that has a double bonded oxygen at the END of the a chain.
• Follow standard rules and add -one to the parent chain for Ketones
• Follow standard rules and change the parent name ending to -al in Aldehydes

Propanone is a ketone. Propanal is an aldehyde. NOTE their endings and where the oxygens are bonded!

Lets try some examples shall we.......

Draw the structural diagrams for the following Ketones:

a) 2, 4 dimethyl 3 pentanone

b) 2 chloro 4 methyl 3 hexanone

c) 1,2,2 trichloro 4,4 difloro 3 butanone

Now try naming the following compound:

Highlight for answer: 2 ethyl 4 floro 2 methyl 3 hexanone

Getting it so far? Great! Let's try a couple of ALDEHYDES and we're all set for today.

*remember an aldehyde is a compound that has a double bonded oxygen at the END of a chain! So Oxygen atoms will be found on the ends of these chains, and will have an ending of -al to give us a clue

Name the following compound:

1) Count 4 carbons = Butane

2) Add ending "-al" to Butane = Butanal

Name of compound = Butanal

The simplest aldehyde is methanal otherwise known as FORMALDEHYDE:

Draw a structural diagram for

2,3 dibromo 4 propyl pentanal

That is all. Post by Ren Ren Flores

ORGANIC CHEMISTRY AND ALKANES

Organic Chemistry is the study of CARBON COMPOUNDS
- Carbon forms multiple covalent bonds

Carbon Compounds can form chains, rings or branches

- There are less than 100,000 non-organic compounds

- Organic compounds number more than 17,000,000

The simplest organic compounds are made of carbon and hydrogen

 

CH4 (Methane) 

 CH3CH3 (Ethane)

- Saturated compounds have no double or triple bonds

- Compounds with only single bonds are called Alkanes and always end in "-ane"

NOMENCLATURE

There are 3 categories of organic compounds

1) Straight chains

2) Cyclic chains

3) Aromatics

STRAIGHT CHAINS

Rules for naming straight chain compounds:

1) Circle the longest continuous chain and name the base chain

- meth, eth, prop, etc... (use  Hydrocarbon Nomenclature Cheat Sheet until it is memorized!)

2) Number the base chin so side chains have the lowest possible numbers

3) Name each side chain using the "-yl" ending

4) Give each side chain the appropriate number

5) List side chains alphabetically

Try naming the following Alkanes! Some of these compounds look a bit different, don't be fooled you fool! :) Answers below!

#1

 

 

#2 

 #3

 

 #4

#5

ANSWERS:

#1 - 2,2 dimethylbutane

Alicyclics and Aromatics (April 20th, 2011)

TODAY.... we learned about the wonderful world of alicyclics and aromatics

Few points before we begin:

• Carbon chains can form 2 types of closed loops
• Alicyclics are loops usually made with single bonds
• If the parent chain is a loop standard naming rules apply with one addition: "cyclo" is added infront of the parent chain

There are 3 different ways to draw organic compounds:

1. Complete structural diagram
2. Condensed structural diagram *
3. Line Diagram * (mostly used because its way easier to draw and you dont have to include all the hydrogens)

*Numbering can start anywhere and go clockwise or counterclockwise on the loop but side chain numbers MUST be the lowest possible!

So let us draw some to show you!

AN EXAMPLE of a condensed structural diagram

• A condensed structural diagram always shows carbons and hydrogens in it

Example of a line diagram:

• loops can also be side chains
• same rules apply but the side chain is given a cyclo- prefix

You also must know how to name a compound!

First, take note of what you see

• You see 2 lines connecting CH2 and C, so you know this organic compound forms a double bond and you must use the ending -ene
• You count the longest carbon chain to be 5 so we use -pent
• -pent + -ene = pentene and this bond occurs at 1 so: 1 pentene
• we see a loop on #3 of the carbon chain so we must use to prefix -CYCLO and there are 3 of the CH's on it so we use propyl and carbon and hydrogen on #2
• #2: 2 methyl
• #3: 3 cyclopropyl

Together this compound is called:

2 methyl 3 cyclopropyl 1 pentene

AROMATICS:

2ND PART OF TODAYS CLASS

• Benzene (C6H6) is a cyclic hydrocarbon with unique bonds between the carbon atoms
• Structurally it can be drawn with alternating double bonds
• Careful analysis shows that all 6 C-C bonds are identical and really represent 1.5 bond
• This is due to electron resonance for electrons are free to move all around the ring

AROMATIC NOMENCLATURE:

• A benzene molecule is given a special diagram to show its unique bond structure

• A benzene can be a parent chain or a side chain
• As a side chain it is given the name PHENYL*

Draw the line diagrams of the following:

a) 1, 4 diethyl 2 methyl Benzene

b) 1,3,5 triethyl 2,4,6 tripropyl benzene

c) 1, 3 diethyl 5 propyl benzene

and that is it!

Post by Ren Ren Flores

BONDING- March 28th

BONDING
Bonds and Electronegativity!


There are 3 main types of bonds in chemistry that we will study...

1. Ionic (metal to non-metal)

• Electrons are transferred from metal to non-metal

      2. Covalent (non-metal to non-metal)

• Electrons are shared between non-metals

      3. Last but not least, Metallic (metal)

• Holds pure metals together by electrostatic attraction...

So today in class, we learned about Electronegativity (en) which is a measure of an atom's attraction for electrons in a bond... for example
Fluorines electronegativity is 4.0, Chlorine is 3.0

• Atoms with greater electronegativity attract electrons more!
• We learned about Polar Covalent bonds: Form from an unequal sharing of electrons, a polar covalent bond is a bond between two non-metals with different electronegativities. Unsymmetrical molecules are usually polar.
• Non-Polar covalent bonds form from equal sharing of electrons, and are symmetrical molecules.

The type of bond formed can be predicted by looking at the difference in electronegativity (en) of the elements *we were also given a periodic table of elements dealing with electronegativity*:

Let's try some examples shall we?

Predict the type of bond formed.

1. H- O

Electronegativity difference:

  2.20

- 3.44

  1.24

1.24 < 1.7 

so we can conclude this bond between Hydrogen and Oxygen is a Polar Covalent bond!

Pretty easy right? Let's try one more and see how you do!

2. K-F

Electronegativity difference: 

  3.99

- 0.82

  3.17

3.17 > 1.7

so we can conclude this bond between potassium and fluorine is an ionic bond!

We good? Try some on your own and the answers will be placed on the bottom! Goodluck!

Predict the type of bond formed.

a) O-O

b) F-Cl

c) Ba - I

d) O-Cl

e) Na-F

f) N-H

g) H-I

Answers:

 *highlight to obtain answers!

a) Non-Polar covalent bond

b) Polar Covalent bond

c) Ionic bond

d) Polar covalent bond

e) Ionic bond

f) Polar covalent bond

g) Non-polar covalent bond

Post by Ren Ren Flores