The chapter chemical bonding deals with the study of attraction between two or more atoms is called chemical bond. The chapter contains important topics like Lewis Theory, Kossel’s theory, Hydrogen Bonding, etc. The average weightage of this chapter in NEET is 12.50%.
Candidates are advised to go through the article to get detailed information about various topics with solved sample questions. Also Check NEET Chemistry Syllabus
Theory in Chemical bonding
The formation of chemical bonds were successfully explained by Albrecht kossel and Gilbert lewis in the year of 1916.Both of them explained the basis of the inertness of noble gases in chemical bonding.
- According to Lewis theory atoms can be viewed as a positively charged kernel .
- At the maximum of eight electrons the outer shell can accommodate.
- The corners of a cube are occupied by the eight electrons in the outer shell which surround the kernel.
- To be a stable configuration the outermost shell contains 8 electrons this is called an octet configuration.
- To achieve this stable configuration atoms form chemical bonds with other atoms.these type of chemical bonds can be formed by either losing or gaining an electron(NaCl, MgCl2) and being particularly in some cases due to sharing of an electron.
- In formation of chemical bonds the Valence electrons take part in it and the only electrons that were present in the outer shell are called valence electrons.
- Lewis symbols were used by Gilbert as a specific notation.
- The number of dots is equal to the valency of an element corresponding to the lewis symbol or 8 minus the number of dots.
Lewis symbols for lithium (1 electron), oxygen (6 electrons), neon (8 electrons)
- The highly electronegative halogens and the highly electropositive alkali metals have been separated by noble gas.
- By gaining an electron Halogens can form negatively,and by losing electron alkali metals can form positively.
- Both of the negatively charged and positively charged electrons have a noble configuration that is eight electrons in the outermost shell.ns2np6 is the general electronic configuration of the noble gases.
- The electrostatic attraction held together the unlike charged particles by a string force between them. For example The electrostatic attraction holds the MgCl2,the magnesium ion and chlorine ions together by a force.this type of chemical bond between two unlike charged particles is called an electrovalent bond.
Types of Bonding
The stability of the resulting compound in the chemical bonding is gauged by the substances and yield compounds that present in that chemical bonding.Due to strength and properties Chemical bonds vary from its type.There are four types of chemical bonds which are formed by atoms and molecules to yield compounds.
There are three types of chemical bonding which are listed below.
- Ionic bonding
- Covalent bonding
- Metallic bonding
- Polar bonding
Types of Structure
Each and every bonding has its own structure here we attach the structure of the bonding.
The transfer of electrons from one atom or molecules to another is a type of chemical bonding that is called Ionic bonding.In this form atom loses an electron which is in turn gained by another atom.The atom develops a negative charge when an electron transfer takes place and this is called anion,and the remaining atom develops a positive charge and that is called the cation.this difference in charge between the two atoms gives the strength to the ionic bond.
If an atom shares its electron to another atom that indicates a covalent bond. When a compound contains its carbon that exhibits this type of chemical bonding.When an atom shares its pair of electrons around the nuclei of atom that leads to the creation of a molecule.
Pink color indicates electron from Hydrogen
Violet color indicates electron from carbon
Polar Covalent Bonding
In nature covalent bonds can either be polar or nonpolar.the more electrons are shared unequally in the covalent chemical bonding and the more electronegative atom pulls the electron pair towards itself and aways from the less electronegative atom. Example for polar covalent bonding is water.
Due to the uneven spacing of the electrons between the atoms there is a difference in charge that arises in different areas of the atom.Both end of the molecule tends to be different one end will be positively charged and another end will be negatively charged.
Comparatively Hydrogen bonding is the weaker form of chemical bonding then ionic and covalent bonding.Where in the hydrogen develops a particle positive charge when the polar covalent bonding between oxygen and hydrogen.This indicates that the electrons attract closer to the more electronegative oxygen atom.this bond gives the tendency for the hydrogen to be pulled towards the negative charges of any neighbouring atom.Hydrogen bond is responsible for the properties of exhibited by water.
Important Formulas for Chemical Bonding
Born Haber Cycle
By Hess law,
Factor Affecting Lattice Energy
|low positive charge||high positive charge|
|large cation||small cation|
|small anion||large anion|
Previous year Solved Sample Questions
- The correct increasing bond angles order is:
Correct Answer: b
[b] BF3:|planar(sp2),|120 degree| bond angle (maximum),Higher the electronegativity of central atom (in sp3| hybridized) larger the bond angle but presence of lone pair of electrons decreases the bond angle. Greater the no. of lone pair of electrons, lower the bond angle.
- The hybridization of atomic orbitals of nitrogenare are
- sp2,sp3 and sp2 respectively.
- sp,sp2 and sp3 respectively.
- sp2,sp and sp3 respectively.
- sp2,sp3 and sp respectively.
- In IF3| the bond angle of F - I - F is
- Equal to 90 degrees.
- Less than 90 degrees.
- Greater than90 degrees.
- Equal to 90 degrees.
- Hydrogen of ‘N’ in N(SiH3)| is
- N is hydridished.
Correct Answer: A
Simple Definitions to Keep in Mind
- The attraction between two or more atoms is called chemical bond.In outermost or valence electrons of atom this attraction may be seen,that there is no clear line to be drawn between them because these behaviors merge into each other seamlessly in various circumstances.
- The chemical bond stabilizes the attractive force which holds various constituents together by the overall loss of energy. This is called chemical bonding.
- If the resulting compound would be more stable then we understand that the bonding between the constituents are stronger. In other end if the resulting compound lacks stability then the chemical bond between the constituents is weak and it undergoes another reaction to give a more stable chemical compound.
- The atoms try to lose their energy to find stability.
- A force is exerted on one by another when matter interacts with another form of matter.the energy decreases when the force is attractive in nature,the energy decreases
- The energy increases when the forces are repulsive in nature.the chemical bond attractive force that binds two atoms together.