ORGANIC CHEMISTRY
INTRODUCTION: - Organic chemistry is the behavioral study of those chemicals which are not only used in our daily life but also touches all walks of our life. Our very own existence, growth and survival depends on organic chemicals. Domain of organic chemistry is so vast that it not only extends to whole universe around us but also exists deep inside us down to the level of microscopic cell and tissue. That is why study of these chemicals though is very simple yet very complex but very important. DEFINITION: Definition of organic chemistry is being constantly modified. In the eighteenth century it was the study of chemicals found in organism. It was so called because it was thought that organic chemicals could not be synthesized in the laboratory. However now large number of chemicals is not only prepared in laboratory but also produce industrially. During the process of research it was discovered that all organic compounds contain carbon. Therefore modern definition is the study of carbon compound. Although there are quite a few compound which contain carbon and are not organic. But the name organic stuck because it is still the study of chemical found in living being 1) Carbon –
CONSTITUENT ORGANIC
Present in all organic compounds
2) Hydrogen - It is not found in few compound but present in most compounds of organic chemicals In addition to these element nitrogen, oxygen, chlorine, bromine, sulfur, phosphor, etc as well as some metals are also present in organic chemicals COMPOUND: A compound is formed when at least two atoms are bonded to each other. However there are several compound which contain more than two atoms
BONDS: -
a) These are forces that keep the two atoms together. b) The attractive and repulsive electrostatic forces between negatively charged electrons and positively charged nuclei bond the two atoms c) Principals of higher stability to posses lower energy is the cause of formation of bond.
d) Electrons posses energy. Lower energy increases stability Hence electrons are constantly thriving for opportunity to reduce their energy. The energy is minimum when the electrons are nearest to nuclei and maximum when farthest from electron. When two atoms come closer electrons of one atom are nearest to nuclei and farthest from the electron of other atom. This conditions suit the electron and nuclei of both atoms. Thus both atoms posses lower energy and achieve higher stability Stability of atoms is also explained on the basis of electronic configuration of inert gasses. All the gasses are highly stable. Nobel gasses (inert gasses) have either two or eight electron in their outer most shell. This explains that atoms are highly stable when they either have eight or two electrons in their outer most shell. Octet rule: - The presence of eight electrons in outer most shell Duet rule: - The presence of two electrons in outer most shell
TYPE OF BOND a) Ionic bond: Ionic bond is formed when both bonding atoms achieve octet or duet by loosing or accepting electron e.g. MgO (Magnesium Oxide)
Magnesium oxide is formed when two electrons from magnesium is transferred to oxygen. Thus both atoms achieve their octet.
b) Covalent bond: - The bond is formed when the atomic orbital overlap each other. The two overlapped atomic orbital form a single orbital called – Bond Orbital which contains electrons from both atoms. Thus electrons in bond orbital is shared by both atoms forming the bond. Sharing of electrons follow octet and duet rule with few exception Covalent bond needs minimum two electrons to form a bond, one from each of the atom forming the bond. However the two electrons can also come from same atom
Single bond: - A bond is called single bond when one pair of electron is shared between bonded atoms. Double bond: - Double bond needs two pairs of electron to be shared. Triple bond: - For formation of triple bond three pairs of electron are required Coordination : It is the bond formed when the two electrons come from the same Atom bond
Sigma bond : ( σ – bond ) Pi – bond (∏ - bond )
The σ – bond is formed by head on overlap of atomic orbital along a line drawn between the nuclei of the two atom. The σ - bond is formed by haring of one pair of electron. Pi – bond is formed in addition to σ – bond. After the formation of σ – bond when orbital of the bonding overlap side ways a pi – bond is formed. Carbon can form maximum two pi – bond Fir