Functional Groups June 6,2011

Functional groups:
-Groups are organic compounds can cantain elements other than C& H
-Most reactive oart of the molecule
-maybe a single atom(such as F, Cl, B or I) or groups of atoms

Ex. Alcohols, Halides(Halogen) or Nitro, aldehydes, ketones, Carboxylic Acids, Ethers, Amines, Amides, Esters

Halides and Nitro compounds
Halogen(Halides) and Nitro cmpounds are named similar to that of simple hydrocarbon and can be attached to alkanes, alkenes and alkynes.

The main-chain name will receive one of the following prefiexs if the appropriate group is attaced.
*Use di- tri- tetra- in front for multiple groups
Halogen                 Nitro
F=floro                  NO2=Nitro
Cl=Chloro
Br=Bromo
I=Iodo

properties of Halogenated compounds.
-compounds contain Halogen(F, Cl, Br & I are generally insoluble in water)
-fluorinated hydrocarbon are inert(unreactive)
-compounds contain Cl or Br are more reactive, but only under drastic dconditions
-compounds contain I are very reactive. I atom can easily be replaced by other functional compounds.
Ex.

 

2-chloro-1,1,2-Trifloroethane

 

Properties of Nitro Compounds(No2)

1. Normally insoluble in water.

2.Unreactive to chemical attack except under drastic conditions.

3.Tend to be explosive.

4.Pleasant odour.

 

Ex. TNT (Tri Nitro Toluene)

 

 

 

Alcohols

-An Alcohol is an organic compound that contains OH(hydroxyl) in functional group.

-Alcohols are named by

·using the longest chain contianing OH

·“E” ending changes to "Ol"

Ex. Methol   

 

 

*Count in the way that give "OH" a smaller number

 

Properties of Alcohol

-The hydroxyl group(OH) in an alcohol tends to make the type of compounds soluble in water.

The hydrocabrn chain tends to be insoluble in water.

 

All alcohol are poisonous to some degree, including C2H5, the form of alcohol present in alcoholic beverages.

 

Ex.

 

propanol

 

Multiple-OH

-if a compound has more than one -OH group number. Add -diol  -triol

 

1,2---ethandiol

 

Aldehydes & Ketones

-both are organic compounds that contain a carbonyl functional group(double boned oxygen)

 

Aldehydes:

-a compound that has doulbe bonded oxygen at the end of a chain

-change the parent ending "e" to "al"

Ex. methanal(simplest)

 

 

  butanal

 

 

Ketones:

-compound has doubled bonds oxygen that are not on either end.

Ex.

propaone.

 

 

Alkenes and Alkynes

=Double & Triple bonds of Carbon

When multiple bonds form, fewer H are attracted to C atom

The position of double/triple bond always have the lowest # put in front of the parent chain

Alkenes:

Definition: simple hydrocarbon with one or more double bonds

CH2=CH2 Ethene

CH2=CH-CH3 Propene

Geometric isomers:

Trans: opposite corner

Cis: both top or bottom

  

CH3CH2┐ ┌CH3

   C=C

CH3CH2CH2┘ └CH2CH3

Alkynes:

- Triple bonds

- naming: end with -yne

CH≡CH   Ethyne

CH≡C-CH3   Propyne

CH3-CH2-CH-C≡C-CH3

        └CH3                 4-methyl-2-haxyne

Alkene:

Alkyne



Chemical Bonding!

Chemical bonding only involves the valence e-

Formed when e- attracted by nucleus of another

Electrostatic force- opposite charge attract; like charge repel

- greater distance, smaller attraction

- greater charge, greater force.

- the force operates equally in all directions


Intermolecular force=force between molecules

Intramolecular force=force within a molecule

Only weak bonds break in melting process



Chemical bonds exhibit various degrees of sharing, depending on the amount of attraction.



Polarity=molecule's electrical balance, but imbalance with electrical charge of elements



Ionic=electrons are transferred

Non polar covalent=shared equally

- Electronegativity difference <0.5

- Attain full electron shells

- Simultaneously attracted

- high melting points(except CH4, O2, F2)

Polar covalent= shared unequally

- higher energy=partial negative charge=δ-

- lower energy=partial positive charge=δ+

- arrow indicates the migration of electrons

Example

Organic Chemistry May 26, 2011

The chemistry of carbon compounds
.

Importance
-organic compounds are seen anywhere in our life.
-Examples of organic compounds: sugar, chair.......

Properties of organic compounds.
-low melting point
-weak or non-electrolytes
-can forms chains of carbon atoms that are linked in a
①straight-line

 

②circular pattern

③branched pattern

    -can link with other atoms in:

    single bonds

  double bonds

  triple bonds

*Versatility organic compounds makes it such an important branch of chemistry.

Alkanes (unbranched/straight chain)

-A hydrogen : only contains O,H

There are different types of hydrogen

                             ways to present them

-no-polar molecules → immiscible with water

-geometry: tetrahedron

-alkanes are saturated alkanes( all C atoms are bonded by single bonds)

*Saturated: not possible for another atom to bond to the structure.

-Naming of alkanes: the names of all hydrocarbons end in "-ane"

Ex. The structure of C2H6?

①          

     full structure                     

②CH3CH2CH3  

Condensed structure

③C3H8

molecular formula

④

 

Ball-and-Stick model

Names of Alkanes.

methane   CH4

ethane      C2H6

propane   C3H8

butane      C4H10

pentane    C5H12

hexane     C6H14

heptane    C7H16

octane      C8H18

nonane     C9H20

decane     C10H22

They are homologous series: a series of organic compounds with similar general formula, possess similar properties.

CnH(2n+2) -----only for alkanes.

Branched hydrocarbons

hydrocarbons have "side branches" which are also hydrocarbon chains.

(substituted carbon/ branched carbon)

Ex

* Alkyl group: an alkane which has lost one hydrogen atom.

The bottom part are alkyl group(CH3)

 

The name of this branced hydrocarbon is 2-methylpropane

*"-pronpane" is the parent hydrocarbon(longest chain)

Carbon has 4 bonds.

  10 hydrogens

Naming: the names of all alkyl groups end in "-yl", because they are alkyl.

Ex. C2H6      ethyl  C2H5

      C3H8      propyl C3H7

Electron Dot & Lewis Diagrams

- nucleus is represented by the atomic symbol

- for individual elements, # of valence electrons

- electrons are represented by dots around the symbol

- a orbit hold a max of 2 electrons

- each orbital gains 1 electron before pair up

Each bond represents 2 electrons

All valence electron must be used

Each element must have a full valence orbital except H

Ex. CH4

Period Table Trend

Metallic Properties:
- the change from metallic to non-metallic going from left to right across the table
- elements become more metallic going down a family

Atomic Radius:
- Decreases across a row from left to right, increase down a group

Reactivity:
- metal&non-metal show different trend
- most metal: Francium
- most non-metal: Fluorine


Ion charge:
- elements ion charges depend on their group


Melting&Boiling point:
- centre of the table-->highest melting/boiling point
- noble gases have lowest melting point

Ionization Energy
- increases up and right
- hellium highest
- Francium lowest

Electronegativity:
- fluorine has highest electronegativity

- Francium has lowest electronegativity

Predicting the # of valence electron

Valence  electron:  electron which can take part chemical reactions also called the " reactable electron" in the outermost(energy level) open electron shell of atom.
-open shell: shell contains less than max. # of electron
-closed shell: contains exactly max. # of electron

valence electron: not in the core, not it d- & f- subshells

ex.
Al=[Ne]3s2 3p1  has 3 valence electron
Pb=[Xe]6s2  4f14  5d10  6p2  has 4 valence electron
Xe=[kr]5s2  4d10  5p6  or[Xe] has 0 valence electron (noble gases)

The periodic law summmarizes the period table
-The periodic law: properties of the chemical elements recur periodically when the elements are arranged from lowest to highest number.