Types Of Bonds

There are thress basic ways in which chemical combination occurs:

(1)    IONLIC  or ELECTROVALENT BOND.

(2)    COVALENT BOND

(3)     COORDINATE BOND.

(1)    IONLIC  or ELECTROVALENT BOND.


    IONLIC  or ELECTROVALENT BOND are formed by transfer of valence electrons from one atom to another. this type of bond unites two atoms one of which has excess electrons than the stable  number (2 or 8) , and the  other is short of electrons. sodium chloride is a typical  compound formed in this way.

Here the sodium atom (2,8,1) transfers its excess electrons to chlorine atom (2,8,7) and thus both attain a  stable inert gas type electron configuration. sodium acquires the electron configuration of neon(2,8) and becomes positively charged chlorine acquires the electrons configuration of argon(2, 8 , 8) and bcomes negatively charged. these oppositely charged ions are held together by electrostatic force of attraction.this type of bond is commonly found in inorganic  compounds.

EXAMPLE...




NOTE THAT

Ionic or electrovalent compounds are non-volatile, soluble in water and possess high melting points. their aqueous solution( aqueous solution are those solution where in inculde in water) conduct electric current.


(2)    COVALENT BOND


COVALENT BOND are formed by mutual sharing of electrons. this type of bond unites two atoms, both of which are short of electrons.
 the two atoms contribute one electron each and share the resulting pair of electrons. HYDROGEN is the simplest  compound formed in this way.

EXAMPLE


THE BOND formed in this way may be single (---- )covalent bond (==) or triple covalent bond (--- =) depending upon the number of shared electrons.such bonds  sre commonly found in organic compounds.

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NOTE THAT.
Covalent compounds are volatile , generally insoluble in water but soluble in organic  solvants. they possess low melting and boiling points.their solution do not conduct  electric current.


(3)     COORDINATE BOND.

coordinate bond is also formed by mutual sharing of electrons but in this case the two electrons that sharred come from the same atom. A coordinate bond unites two atoms, one of which has a spare pair of electrons and the other is short of a pair of electrons. the first atom (donor atom) contributes one pair (lone pair) of electrons and the second atom (acceptor atom) accepts it.after the formation of the bond , the lone pair of electron is held in common. the coordinate bond is represented by an arrow, pointing away from the donor atom.An excellent illustration of the coordinate bond is found in the boron  hydride-ammonia complex .

THE FULL EXPLINATION WITH PICTURE EXAMPLE IS COOMING SOON...............!!!

STRUCTURE OF ORGANIC MOLECULES.

 STRUCTURE OF ATOM.

According to "'Rutherford-bohr" theory ,the atom is made of acentral postively charged nuceus containing positively charged particles called protons, and neutral particles called neutrons. the nucleus is surrounded by negatively charged particles called electrons.

The electrons revolve around the nucleus in fixed orbits or energy levels.while the electron moves in such a level, it possesses a definite quantity of energy and it neither emits nor absorbs energy.the electrons are arranged in the orbits so that the maximum number of electrons in the various orbits starting from the one nearest the nucleus is 2,8,18,32,18,8.the outermost orbit of electrons in different atoms (except inert gases),is incomplete and the electrons in it are known as the ""VALENCE ELECTRONS"".

 WHY ATOMS COMBINE TO FORM MOLECULES? { CHEMICAL BONDS }

The classical concept about the formation of molecule (chemical bond); is based upon the electronic structure of atoms of inert gases have either 2 or 8 electrons in the outermost orbit.the gases do not enter into chemical combination and,therefore, are assumed to have complete or stable orbits.the atoms of all other elements have incomplete outermost orbits and tend to complete them by chemical combination with other atoms.G.N.lewis proposed that it is the urge of atoms to complete their outermost orbit of electrons as in the inert gases, which is responsible for chemical  combination. in other word, chemical combination  between two atoms resulte from the  redistribution of electrons between them so that both the atom complete their outermost orbits or acquire stable electronic configuration possessed by their inert gases.

GENERAL CLASSICCATION OF ORGANIC COMPOUNDS.

Organic compounds cab be classicfiedon the basic of structure as below..

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 1)     OPEN CHAIN COMPOUNDS.

those organic compounds which have open chain  structure are called""OPEN CHAIN COMPOUNDS"". aliphatic compounds or alicyclic compounds. it has two type:

A)   STRAIGHT CHAIN COMPOUNDS.

these compounds have no branch in their structure but may contain single (---),double (==) or triple (= --) bond.

EXAMPLE.
 

 

B)  BRANCH CHAIN.

 these compounds have one or more than one branch in their.

EXAMPLE.

A1)  ISO COMPOUNDS.

     those compounds which have a methylgroup (CH3------) attached to the 2nd last carbon atom of continuous chain.

EXAMPLE.

B2)   NEO COMPOUNDS.

 those compounds which have two methyl (CH3------) group attached to the 2nd last carbon atom of the continuous chain.

EXAMPLE.

2) CLOSE CHAIN COMPOUNDS.

those organic compounds which have cycle or ring in their structure are called "" CLOSE CHAIN ORGANIC COMPOUNDS"".(in these compounds 1st and last carbon atoms are connected with each other.)

EXAMPLE.

There are two types of close chain compounds.
1) HOMOCYCLINC COMPOUNDS.
2) HETROCYCLIC COMPOUNDS.
 
1) HOMOCYCLINC COMPOUNDS.

those compounds in which ring/cycle is made of carbon atom only are called "" HOMOCYCLINC COMPOUNDS   or  CARBOCYCLIC COMPOUNDS"".
EXAMPLE.

there are two types of HOMOCYCLINC COMPOUNDS.
           A) ALICYCLIC COMPOUNDS (Non Benzonide)
          B)  AROMATIC COMPOUNDS.(Benzonide)

 A) ALICYCLIC COMPOUNDS (Non Benzonide)

 the homocyclic compounds having no benzene ring in their structure are called alicyclic compounds.(Ring contain three or more carbon  atomes and resembling aliphatic compounds.)

EXAMPLE.

 B) AROMATIC COMPOUNDS.(Benzonide)
the homocyclic compounds containing at least one or more""BENZENE"" ring in their structure are called  "" AROMATIC COMPOUNDS  or  BENZONIDE COMPOUNDS.""the aromatic compounds have quite a different behaviour from the open chain comounds. all the aromatic compounds have special smell(Aroma).

EXAMPLE.




2) HETROCYCLIC COMPOUNDS.
the cyclic compounds in which ring consiste of atome of more than one kind are called ""HETROCYCLIC COMPOUNDS"" or HETROCYCLES"".

EXAMPLE