Question

expalin different bond parameters.

Answer 1

Definition: A covalent bond is a chemical link between two atoms in which electrons are shared between them. Examples: There is a covalent bond between the oxygen and each hydrogen in a water molecule (H2O). Each of the covalent bonds contains two electrons - one from a hydrogen atom and one from the oxygen atom. Both atoms share the electrons.

Types of covalent bond:-

Single bond:-A covalent bond formed by the mutual sharing of one electron pair between two atoms is called a "Single Covalent bond." It is denoted by single short line Examples:In single bond formation each atom provide one electron.Double bond:-A covalent bond formed between two atoms by the mutual sharing of two electron pairs is called a "double covalent bond". It is denoted by double short line Examples:Triple bond:-A covalent bond formed by the mutual sharing of three electron pairs is called a "Triple covalent bond". It is denoted by triple short line . Examples:Polar bond:-A covalent bond formed between two different atoms is known as Polar covalent bond. For example when a Covalent bond is formed between H and Cl , it is polar in nature because Cl is more electronegative than H atom . Therefore, electron cloud is shifted towards Cl atom. Due to this reason a partial -ve charge appeared on Cl atom and an equal +ve charge on H atom Examples:Non-polar bond:-A covalent bond formed between two like atoms is known as Non-polar bond. Since difference of electronegativity is zero therefore, both atoms attract electron pair equally and no charge appears on any atom and the whole molecule becomes neutral. Examples: H - H Cl - Cl 

Answer 2

BOND PARAMETERS – Bond length, Bond angle, Bond enthalpy and Bond order

Atoms combine together to become stable. The combination takes place by forming bonds. There are different types of bond viz. ionic or electrovalent bond, covalent bond and coordinate bond. Every bond has some feature associated with it. This article discusses the different features or characteristics of bonds which can also be called as bond parameters.



Bond Length

Bond length is defined as the distance between the centres of the nuclei of two bonded atoms in equilibrium position.

Stronger the force of attraction between the bonding atoms, smaller the bond length.

Bigger the size of atom, longer the bond length.

It is measured by spectroscopic, X-ray diffraction and electron diffraction technique.

Each atom of the bonded pair contributes to the bond length.

In case of covalent bond, the contribution by each atom is called covalent radius of that atom.

Bond Angle

Bond angle is defined as the angle between the two bonds i.e. angle between two orbitals containing bonding electron pairs around the central atom in a complex molecule or an ion.

It is measured in degrees and is calculated using spectroscopic method.

It gives the idea about the distribution of bonded electron pairs around the atoms.

It helps in the determination of shape of the molecules.

Bond Enthalpy

It is defined as the amount of energy required to break one mole of the bond of particular type between two atoms in gaseous states.

Bond enthalpy is directly proportional to the strength of the bond between the molecules.

In polyatomic molecules, the two bonds of the same type can have different bond enthalpy.
For e.g.: Two O-H bonds of water molecule have different bond enthalpy.

Due to differences in bond enthalpy, polyatomic molecules have average bond enthalpy.

Bond Order

It is the number of bonds formed between the two atoms in a molecule. This definition is according to the Lewis description of covalent bonds.

Isoelectronic molecules or ions have same bond order.
For e.g. F2 and O22- are isoelectronic molecules and so have same bond order of 1.

Greater the bond order, bond enthalpy increases and bond length decreases.