Nature of substrate & factors in a chemical reactions

Chemical Bonding

There are three types of chemical bond :

(a) Covalent Bond(b) Ionic Bond (c) Coordinate Bond


(a) Covalent Bond :

Covalent bonds are chemical bonds between two non-metal atoms which is made by sharing of electron called as "covalent bond". These shared electron pairs are known as shared pairs or bonding pairs, and it stabilizes balance of attractive and repulsive forces between atoms.

OR

Covalent bonding is close to the heart of organic chemistry. This is where two atoms share electrons in a bond.

The goal of each atom is to fill its octet as well as have a formal charge of zero . To do this, atomic nuclei share electrons in the space between them. This sharing also allows the atoms to reach a lower energy state , which stabilizes the molecule.

Most reactions in chemistry are due to molecules achieving a lower energy state.

Covalent bonds are most frequently seen between atoms with similar electronegativity.

In molecules that only have one type of atom, e.g. H2 or O2 , the electronegativity of the atoms is necessarily identical, so they cannot form ionic bonds. They always form covalent bonds.

Carbon is especially good at covalent bonding because its electronegativity is intermediate relative to other atoms.That means it can give as well as take electrons as needs.

Example : Cl2, I2, Br2 . Any same electronegativity group having single bond i.e. Covalent Bond.

Covalent Bond

Covalent Bond

Covalent Bond

(b) Ionic Bond :

The bond in which one or more electrons from one atom are donated to another atom, to form resulting positive and negative ions which attract each other called as Ionic Bond.

OR

Ionic bonding is when positively and negatively charged ions stick to each other through electrostatic force. These bonds are slightly weaker than covalent bonds and stronger than Van der Waals bonding or hydrogen bonding.

In ionic bonds the electronegativity of the negative ion is so much stronger than the electronegativity of the positive ion that the two ions do not share electrons. Rather, the more electronegative ion assumes full ownership of the electron

Example : NaCl, LiCl, HCl, HI, HBr, HF, NaCN, HCN, KCN

Ionic Bond

Ionic Bond

Ionic Bond

(c) Coordinate Bond/Dative Bond :

The bonding formed due to sharing of an electron pair by one of the atom to another atom called Coordinate bond/Dative Bond.

Example : BF3(OEt)2, NH3AlCl3

Coordinate Bond

Coordinate Bond

Coordinate Bond