s bond and p bond

• Acid / base reaction
  Acid donates H ⁺ and base accepts H ⁺.

  CH₂NH₂ + H ⁺ ® CH₂ NH₃⁺

• Redox reaction
  Reduction and Oxidation

  Oxidation: CH₃CH₂OH ® CH₃CHO ® CH₃COOH (ethanol ® ethanal® ethanoic acid)

  Reduction: CH₃COOH ® CH₃CH₂OH (ethanoic acid ® ethanol)

• Condensation
  Two molecules join to form a large molecule and a small molecule is evolved.

  Acid + Alcohol ® Ester + water (This example is also known as esterification)

• Hydrolysis
  Breaking off a molecule by adding water.

  CH₃CºN + H₂O ® CH₃CONH₂ (ethanonitrile + water ® ethanoamide)

• Elimination
  Removal of a group from a molecule

  CH₃CH₂Br ® CH₂=CH₂ + HBr

  CH₃CH₂OH ® CH₂=CH₂ + H₂O

The reactions listed so far I believe are quite familiar for people who did their chemistry in junior high, high school or GCSE. Reactions after this point are the new bit for you (I hope).

Before we get into details of these reactions, first of all what are nucleophile, electrophile and free radicals??

1. Nucleophile have a pair of electrons ( a lone pair of electron or a p bond if you like ) that attack an electron deficient site ( gap ) site on another molecule.
   Nucleophile can be negative or neutral

   OH^-, and (:CºN (can be written as CN^-) are examples of nucleophile with negative charge

   CH₃CH₂(:NH₂, H₂O(water), NH₃, and CH₂=CH₂ are examples of neutral nucleophile.

2. Electrophile have an electron deficient site (gap) and attack on electron concentrated site.
   Electrophile can be positive or neutral

   CH³⁺, H⁺, and NO₂⁺ are examples of positive electrophile.

   Br₂ and HBr are examples of neutral electrophile.

3. Free radical is very reactive partical with an unpaired electron. It is formed when a covalent bond is split up by a very strong energy source such as UV (Ultra Violet) ray.

   When Cl₂ is split up by UV, homolitic fission occurs and free radicals are formed. Cl-Cl® Cl* *Cl

• Nucleophilic substitution: It happens with halogenoalkanes.

  CH₃CH₂Br + OH^- ® CH₃CH₂OH + Br^-
  

• Nucleophilic addition: It happens with aldehydes and ketones ( C=O group ).

  CH₃CHO + HCN ® CH₃CHCNOH

  
  

• Electrophilic substitution: It happens with aromatic compounds ( benzene ).

  1)Making electrophile
  CH₃Cl + AlCl₃ ® CH₃⁺ + AlCl₄^-

  2)The reaction

  3)Leaving H⁺ react with AlCl₄^-
  AlCl₄^- + H⁺ ® AlCl₃ + HCl

• Electrophilic addition: It happens with alkenes.

  C₂H₄ +HBr ® CH₃CH₂Br

• Free radical substitution: It happens with alkanes.
  It is divided into three stages: initiation, propagation, termination

  Overall reaction: CH₄ + Cl₂ ® CH₃Cl + HCl

  Initiation: Cl-Cl ® Cl* *Cl

  Propagation:

  CH₄ + Cl* ® CH₃ + HCl
  CH₃* + Cl₂ ® CH₃Cl + Cl*
  CH₃Cl + Cl* ® CH₂Cl* + HCl
  CH₂Cl* + Cl₂ ® CH₂Cl₂ + Cl*

  Termination: (when all the free radicals are used up)

  CH₃* *Cl ® CH₃Cl
  CH₃* *CH₃ ® CH₃-CH₃

  Note: Cl* and Cl* can also form back to Cl-Cl but only happens on vessel wall.

• Free radical addition: It is used to generate polymers, such as polyethene.
  It is divided into three stages: initiation, propagation, termination

  Initiation Propagation Termination

Structural isomers

Positional isomers

Stereo isomers

Geometrical isomers (cis and trans isomerism)

Geometrical isomers have the same structure and molecular formula but differ in the geometric arrangement.
For example: 1,2-dibromoethene

Optical isomers

Optical isomers have the same molecular formula and structure but different arrangement in space, as the isomers are mirror image to each other and cannot be superimposed.
For example: butane-2-ol
Optical isomers must at least have one chiral center. Chiral is a carbon with four atoms or groups attached to it which no matter how molecule is rotated, twisted or turned, it cannot superimpose to its mirror images.