Glossary

A B C D E F G H I J K L M
N O P Q R S T U V W X Y Z
A

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B

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C

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Carbocation

A carbon atom with a positive charge on it.  It bonds by accepting a pair of electrons from a nucleophile

D

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Distillation    

Below is a diagram of the simple distillation apparatus often used in organic chemistry.  The products from the reaction taking place in the round bottomed flask are made and collected straight away e.g. oxidation of primary alcohols.  This is in contrast to the reflux method which uses more or less the same apparatus but is set up so that the products are not collected straight away.  

1.  Is the power supply

2. Is the heater, alternatively, an ordinary Bunsen burner can be used.

3. Is the round bottomed flask containing the reactants.

4.  4. Is a connector which connects the flask to the rest of the apparatus and holds the thermometer at the correct height.

5. Is a condenser which is attached to the cold water supply.

6.  Is the flask needed to catch the products as they are formed.

 

E

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Electronegativity

This is the tendency of an atom in a bond to attract electrons towards itself.  The electronegativities of the elements of the periodic table are shown here.  Generally, electronegativity increases as you go towards the top left hand corner of the periodic table.  Excluding group 0, the three most electronegative element in the periodic table are fluorine, oxygen and nitrogen.

  Group
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
1 H
2.1 		                                He
0
2 Li
0.98 		Be
1.57 		                    B
2.04 		C
2.55 		N
3.04 		O
3.44 		F
3.98 		Ne
0
3 Na
0.93 		Mg
1.31 		                    Al
1.61 		Si
1.9 		P
2.19 		S
2.58 		Cl
3.16 		Ar
0
4 K
0.82 		Ca
1 		Sc
1.36 		Ti
1.54 		V
1.63 		Cr
1.66 		Mn
1.55 		Fe
1.83 		Co
1.88 		Ni
1.91 		Cu
1.9 		Zn
1.65 		Ga
1.81 		Ge
2.01 		As
2.18 		Se
2.55 		Br
2.96 		Kr
0
5 Rb
0.82 		Sr
0.95 		Y
1.22 		Zr
1.33 		Nb
1.6 		Mo
2.16 		Tc
1.9 		Ru
2.2 		Rh
2.28 		Pd
2.2 		Ag
1.93 		Cd
1.69 		In
1.78 		Sn
1.96 		Sb
2.05 		Te
2.1 		I
2.66 		Xe
2.6
6 Cs
0.79 		Ba
0.89 		La
1.1 		Hf
1.3 		Ta
1.5 		W
2.36 		Re
1.9 		Os
2.2 		Ir
2.2 		Pt
2.28 		Au
2.54 		Hg
2 		Tl
2.04 		Pb
2.33 		Bi
2.02 		Po
2 		At
2.2 		Rn
0
7 Fr
0.7 		Ra
0.89 		Ac
1.1 		Rf
Db
Sg
Bh
Hs
Mt
Uun
Uuu
Uub
           
 
 
  Lanthanides Ce
1.12 		Pr
1.13 		Nd
1.14 		Pm
1.13 		Sm
1.17 		Eu
1.2 		Gd
1.2 		Tb
1.1 		Dy
1.22 		Ho
1.23 		Er
1.24 		Tm
1.25 		Yb
1.1 		Lu
1.27
  Actinides Th
1.3 		Pa
1.5 		U
1.38 		Np
1.36 		Pu
1.28 		Am
1.3 		Cm
1.3 		Bk
1.3 		Cf
1.3 		Es
1.3 		Fm
1.3 		Md
1.3 		No
1.3 		Lr

 

Electrophile

An ion or molecule with a positive charge which is attracted to an area of negative charge.  It bonds by accepting a pair of electrons.  eg, H+, Cl+, CH3+, NO2+. 

 

F

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Free Radical   

A molecule or ion which has an unpaired electron.  It is shown by a dot e.g. X. They are very reactive because they can't wait to pair up, hence reactions involving free radicals can be quite quick and violent!

Functional Group                           

The functional group is the part of the molecule that determines the types of reactions the compound will undergo.

For example if a molecule has a C=C double bond it will decolourise bromine water.

 

G

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H

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Homolytic Fission

Fission means bond breaking.  When a bond is broken by homolytic fission it means that the bond is broken evenly.  One electron goes to each half of the broken molecule.  e.g.

Two chlorine free radicals are formed.  The "fish hooks" show the movement of one electron each.

Heterolytic Fission

When a bond is broken by heterolytic fission, it is broken unevenly.  Both electrons in the bond go to the same atom to form one positive and one negative species.  The positive species is called an electrophile and the negative species is called a nucleophile.

I

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J K

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L

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M

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N

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Nucleophile

An ion or molecule with a negative charge or a lone pair of electrons.  It bonds by donating a pair of electrons.  eg Cl-, NH3, OH-, CN-.

O

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P  Q

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Polarity

If a covalent bond is made up of identical atoms e.g.. H-H then there is no difference in their electronegativities and the electrons will be distributed equally around the bond.  The electron distribution can be shown in a charge cloud representation:

However if 1 atom in the bond is more electronegative then it will pull the electrons in the bond towards itself e.g. in the H-Cl bond the chlorine atom is more electronegative giving the chlorine a partial negative charge (d-) and the hydrogen a partial positive charge (d+).

Physical Properties

  •  
    • R

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    Reflux

    A simple reflux apparatus is shown below.  The conditions for reflux are more vigorous, and the condenser is positioned vertically to prevent any of the reactants from evaporating.  This method is used for the oxidation of secondary alcohols.

     

    S

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    STRUCTURAL FORMULA           

    The structural formula of a compound shows how the atoms and bonds are arranged in the molecule.

    For example the structural formula of ethanol is shown below

    The molecular formula tells you what elements the compound is made of and how many atoms of each element there are.  For example the molecular formula of ethanol is C2H6O, indicating that there are 2 carbon atoms, 6 hydrogen atoms and 1 oxygen atom.  

     

    T

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    U

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    V

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    W X Y Z

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