This document discusses different types of chemical bonds including ionic bonds, covalent bonds, hydrogen bonds, metallic bonds, peptide bonds, phosphodiester bonds, and glycosidic bonds. It provides examples and brief descriptions of each bond type. The key points are that different types of chemical bonds vary in their mechanism of formation and strength of attraction between atoms, and different bond types play important roles in holding together biological macromolecules like DNA, RNA, proteins, and contributing to their structure and function.

1. Chemical
Bonding
By: Dr. Akalesh K. Verma
Assistant Professor,
Cotton College State University,
Assam, Guwahati-01
Email: akhileshverma07@gmail.com

2. Introduction
Chemical bonding provides the energy
necessary to hold two different atoms
together as part of a chemical compound.
Strength of the bond depends on the
molecules or atoms involved in the
process of bond formation.

3. Types of Chemical Bonding
1. Ionic Bonds
2. Covalent Bonds
3. Hydrogen Bonds
4. Metallic Bonds

4. Ionic Bonds
Ionic bonding is the complete transfer of
valence electron(s) between atoms. It is a type
of chemical bond that generates two
oppositely charged ions. In ionic bonds, the
metal loses electrons to become a positively
charged cation, whereas the nonmetal accepts
those electrons to become a negatively
charged anion.
Ionic bonds are generally formed between
metals and nonmetals

5. Example of Ionic Bond
A classic example of ionic bonding is between Na and Cl. Na is a
silvery metal. It has 1 valence electron. Cl is a yellow-green gas,
and it needs 1 electron to fill its valence shell. The ions now have
opposite charges and are attracted to each other by
electrostatic forces. They form a crystal with the rock salt
structure.

6. Covalent Bonds
A type of chemical bond in which there
is mutual sharing of electrons between
two atoms is called covalent bond. It is
further classified into single, double,
and triple covalent bond with respect to
mutual sharing of one, two, and three
bonds respectively.

7. Example of Covalent Bond
When two hydrogen atoms get close enough together, the
attraction is balanced in both directions and they share the
electrons between them. A covalent bond is made and hydrogen
gas (H2) is Formed.

8. Hydrogen Bonds
A hydrogen bond is the attractive force
between the hydrogen attached to an
electronegative atom of one molecule and
an electronegative atom of a different
molecule.
Usually the electronegative atom is
oxygen, nitrogen, or fluorine, which has a
partial negative charge.

9. Example of Hydrogen Bond
Each hydrogen atom is covalently bonded to the oxygen via a
shared pair of electrons. Oxygen also has two unshared pairs of
electrons. Thus there are 4 pairs of electrons surrounding the
oxygen atom, two pairs involved in covalent bonds with hydrogen,
and two unshared pairs on the opposite side of the oxygen atom.
Oxygen is an "electronegative“ atom compared with hydrogen.

10. Metallic Bonds
Metallic bonding is the type of bonding
found in metallic elements. This is the
electrostatic force of attraction
between positively charged ions and
delocalized outer electrons.
Metallic bonding refers to the
interaction between the delocalized
electrons and the metal nuclei.

11. Example of Metallic Bond
As the metal cations and the electrons are oppositely charged,
they will be attracted to each other, and also to other metal
cations. These electrostatic forces are called metallic bonds,
and these are what hold the particles together in metals.

13. THE PEPTIDE BOND
 Proteins are linear polymers composed of amino acids linked together by peptide
bonds.
 The chains containing less than 50 amino acids are called “peptides”, while those
containing greater than 50 amino acids are called “proteins”.
 Peptide bond is formed by the condensation of the carboxyl group of one amino
acid and the amino group of the second amino acid with the elimination of
water.
• 2 Amino acids – Dipeptide.
• 3 Amino acids –Tripeptide
• 4-10 Amino acids –Oligopeptide
• >50 amino acids --Protein

14. THE PEPTIDE BOND FORMATION

15. PHOSPHO-DIESTER BOND
Phospho-diester bonds are central to all life on Earth.
Phospho-diester bonds make
up the backbone of the strands
of nucleic acid. In DNA and RNA,
the phosphodiester bond is the
linkage between the 3' carbon
atom of one sugar molecule and
the 5' carbon atom of another,
deoxyribose in DNA and ribose
in RNA. Strong covalent bonds
form between the phosphate
group and two 5-carbon ring
carbohydrates (pentoses) over
two ester bonds.

16. GLYCOSIDIC BOND
In chemistry, a glycosidic bond or glycosidic
linkage is a type of covalent bond that joins a
carbohydrate (sugar) molecule to another
group, which may or may not be another
carbohydrate. Formation of ethyl gluoside :
Glucose and ethanol combine to form ethyl
glucoside and water.

17. FORMATION OF GLYCOSIDIC BOND
1.
2.

18. CHEMICAL BONDS AND THEIR IMPORTANCE IN BIOLOGY
Type of Bond Characteristics Biological Importance
Covalent
Bonding electrons shared between 2
atoms.
This type of bond holds together
the long chains of
macromolecules (DNA, RNA and
Proteins).
Ionic
Complete transfer of electron from one
atom to another. Oppositely charged
atoms attract one another.
Compounds with ionic bonds
split into ions in water. Ions
conduct electricity. Gives
specialized cells (nerve, muscle)
excitable properties.
Hydrogen
Weaker than covalent or ionic bonds.
Formed between a hydrogen covalently
bonded to O or N and a second O or N.
The second O or N may be on the same
molecule or on another nearby
molecule.
Water: makes water molecules
stick together. Responsible for
many of the strange properties of
water.
Proteins: cause protein chains to
spiral and bend, giving unique
shapes.
DNA: hold together the 2 chains
to form the double helix. Allow
chains to "unzip" for replication
and transcription.