CHEMICAL BONDING and CHEMICAL REACTION
Chemical Bond electrons and protons, the atom is called
It is the attraction between two atoms or If the atom has more electrons than
ions that holds them together. protons, it is a negative ion, or Anion. e.g.
It is caused by the electrostatic force of Hydroxide anion (OH-), Oxide anion (O2-)
attraction between opposite charges, either If it has more protons than electrons,it is a
between electrons and nuclei, or as the positive ion, or Cation. e.g. Silver (Ag+),
result of a dipole attraction. Hydronium (H3O+)
Covalent or Ionic bonds are strong bonds Ionic Compound is a compound
and Dipole–Dipole bond and Hydrogen composed of cations and anions held
bond are weak bonds. together by electrostatic forces.
Valence Ionic Bond
The valence or valency of an element is a It formed by the electrostatic force of
measure of its combining power with other attraction between two oppositely charged
atoms when it forms chemical compounds ions.
or molecules. It is formed due to transfer of electrons
It is denoted using a positive or negative from one atom to another.
integer used to represent this binding Generally, it is formed between a metal
capacity. It is also known as valency or atom and a nonmetal atom.
valence number. Its properties are Crystaline, stronger force
of attraction, thermally stable, low
Table of Element Valences
volatality, high density, high melting point
No. Element Valence and boiling point.
1 Hydrogen (-1), +1 e.g. NaCl, MgO2, CaCl2, etc.
2 Helium 0
3 Lithium +1
4 Beryllium +2
5 Boron -3, +3
6 Carbon (+2), +4
7 Nitrogen -3, -2, -1, (+1), +2, Covalent Bond
+3, +4, +5
8 Oxygen -2 It formed between two atoms due to the
9 Fluorine -1, (+1) sharing of electron pairs.
10 Neon 0 Generally, it formed by two nonmetal
Its properties are low melting point and
Ions boiling point, non-conductor, and soluble
in non-polar solvent, rigid and directional
It is a charged atom or molecule. It is
charged because the number of electrons
e.g. H2, Cl2, HCl, etc.
do not equal the number of protons in the
atom or molecule.
An atom can acquire a positive charge or a
negative charge depending on whether the
number of electrons in an atom is greater
or less then the number of protons in the Coordinate Covalent Bond
When an atom is attracted to another atom It is formed when one atom donates both
because it has an unequal number of of the electrons to form a single covalent
bond. These electrons originate from the
donor atom as an unshared pair.