Ionization Potential

Ionization Potentials for beginners.
All the best.

1. Ionization Potential Ionization Potential
1M.Qudratullah Saqib, Chem Engg.
By,
Engr. Muhammad Qudratullah Saqib.
UET Lahore.

2. ContentsContents
Introduction to Ionization Energy
Factors affecting the Ionization Energy
Effective nuclear charge
Atomic size i.e. atomic radius
Principle quantum number
Shielding effect
Half filled and completely filled orbitals
Nature of orbitals
The extent of penetration of valence electrons
Trends in Ionization Potential
2M.Qudratullah Saqib, Chem Engg.

3. Ionization EnergyIonization Energy
The process of removing an electron from an isolated atom
to form a positive ion.
First ionization energy (I
1
):
Amount of energy required to remove the most loosely
bound electron from an isolated gaseous atom to form a
cation.
Second ionization energy (I
2
):
Amount of energy required to remove a second electron
from the gaseous monopositive cation to form di-positive
cation.
3M.Qudratullah Saqib, Chem Engg.

4. Ionization energies are usually expressed in electron
volts (eV) per atom or in kilo-Joules per mol (kJ/mol)
--> 1eV/atom=96.48 kJ/mol
Value of each ionization energy will increase with each
removed electron, since the attractive influence of the
nucleus increases and will require more energy for the
removal of an electron from more positive charges.
Ionization energies measure how tightly electrons are
bound to atoms. Low energies indicate ease of removal of
electrons and vice versa.
Ionization Energy(Cont.)Ionization Energy(Cont.)
4M.Qudratullah Saqib, Chem Engg.

5. Ionization Energy(Cont.)Ionization Energy(Cont.)
5M.Qudratullah Saqib, Chem Engg.

6. Factors affecting Ionization Factors affecting Ionization
PotentialPotential
Effective nuclear charge
Atomic size i.e. atomic radius
Principle quantum number
Shielding effect
Half filled and completely filled orbitals
Nature of orbitals
The extent of penetration of valence electrons
6M.Qudratullah Saqib, Chem Engg.

7. Factors affecting Ionization Factors affecting Ionization
Potential(Cont.)Potential(Cont.)
Effective Nuclear Charge:
Greater the magnitude of effective nuclear charge, higher is
the amount of energy needed to remove the outermost shell
electron.
Atomic Size:
Higher the value of atomic radius of an atom, lower will be
the ionization energy.
7M.Qudratullah Saqib, Chem Engg.

8. Factors affecting Ionization Factors affecting Ionization
Potential(Cont.)Potential(Cont.)
Principal Quantum Number (n):
With the increase of principal quantum number of the
orbital from which the electron is to be removed, the
magnitude of ionization potential decreases.
Shielding Effect:
With the increase of shielding effect ionization potential
decreases.
8M.Qudratullah Saqib, Chem Engg.

9. Factors affecting Ionization Factors affecting Ionization
Potential(Cont.)Potential(Cont.)
Half-filled and completely-filled orbitals:
The ionization potential of an atom having half-filled or
completely-filled orbitals in its electronic configuration is
relatively higher than that expected normally from its
position in the periodic table.
Nature of Orbitals:
To remove an electron from f-orbital will be easiest while to
remove the same from s-orbital will be the most difficult
according to following order,
ns < np < nd < nf
9M.Qudratullah Saqib, Chem Engg.

10. Ionization energy generally increases from left to right in
a period because of the increase in nuclear charge and
decrease in atomic radius.
Ionization energies generally decrease down a group due
to the shielding effect and increase in atomic size.
Deviations from these trends can usually be traced to
repulsion between electrons, particularly electrons
occupying the same orbitals.
When all valence electrons have been removed, the
ionization energy takes a quantum leap.
Trends in Ionization PotentialTrends in Ionization Potential
10M.Qudratullah Saqib, Chem Engg.

11. Trends in Ionization PotentialTrends in Ionization Potential
11M.Qudratullah Saqib, Chem Engg.

12. Trends in Ionization PotentialTrends in Ionization Potential
12M.Qudratullah Saqib, Chem Engg.