This document provides an overview of electronic configuration and the rules for writing the electronic configurations of elements. It defines electronic configuration as describing how electrons are distributed in an atom's atomic orbitals. It discusses the quantum numbers that describe atomic orbitals and electrons, including the principal, azimuthal, magnetic, and spin quantum numbers. It also explains the Aufbau principle, Pauli exclusion principle, and Hund's rule that govern the filling of electrons in orbitals to write electronic configurations. The goal is for students to understand these concepts and be able to write the electronic configuration of different elements.

1. PHARMACEUTICAL INORGANIC
CHEMISTRY
MODULE CODE : PST 04210
MODULE CREDIT : 12
PREPARED BY PHILIPO RAPHAEL

2. ELECTRONIC CONFIGURATION OF
ATOM
LEARNING
 Define the term electronic configuration
 Describe quantum numbers
 Describe atomic orbitals
 Explain rules used in filling electrons in
orbital
 Write the electronic configuration of
different elements

3. ELECTRONIC CONFIGURATION
 The electron configuration of an element
describes how electrons are distributed in its
atomic orbitals.
 An orbital is a region whereby the electrons are
likely to be found in an atom
 The standard notation for the indication of the
electronic configuration of atoms is written in a
sequence of the label names of each atomic
subshell with the number of electrons assigned
to that specific subshell written in superscript.

4. ELECTRONIC CONFIGURATION

5. ELECTRONIC CONFIGURATION
 These subshells are made up of atomic orbitals.
The four subshell labels that are used are s, p, d,
and f. The maximum number of electrons allowed
in each of these subshells are 2, 6, 10, and 14
respectively
 The electronic configuration of elements can also
be written with the help of noble gases. These
noble gases have completely filled outermost
shells can be prefixed to the outermost shell of
the element whose electronic configuration must
be noted.

6. ELECTRONIC CONFIGURATION
NOTATION
 However, the standard notation often yields
lengthy electron configurations (especially for
elements having a relatively large atomic
number).
 In such cases, an abbreviated or condensed
notation may be used instead of the standard
notation. In the abbreviated notation, the
sequence of completely filled subshells that
correspond to the electronic configuration of a
noble gas is replaced with the symbol of
that noble gas in square brackets

7. ELECTRONIC CONFIGURATION
NOTATION

8. ELECTRONIC CONFIGURATION
 The maximum number of electrons that can
be accommodated in a shell is based on the
principal quantum number (n). It is
represented by the formula 2n2, where ‘n’ is
the shell number
 The subshells into which electrons are
distributed are based on the azimuthal
quantum number (denoted by ‘l’).

9. ELECTRONIC CONFIGURATION
 This quantum number is dependent on the value
of the principal quantum number, n. Therefore,
when n has a value of 4, four different subshells
are possible.
 When n=4. The subshells correspond to l=0, l=1,
l=2, and l=3 and are named the s, p, d, and f
subshells, respectively.
 The maximum number of electrons that can be
accommodated by a subshell is given by the
formula 2*(2l + 1).

10. QUANTUM NUMBER
Quantum numbers are numbers used to
describe atomic orbitals and to label
electrons that reside in them
 These numbers are derived from the
mathematical solution of the Schrödinger
equation for the hydrogen atom

11. 4 QUANTUM NUMBERS
 Principle quantum number (n)
 Angular momentun quantum number (l)
 Magnetic quantum number (ml)
 Spin quantum number (ms)

12. PRINCIPAL QUANTUM NUMBER
 The first quantum number describes the
electron shell, or energy level, of an atom.
The value of n ranges from 1 to the shell
containing the outermost electron of that
atom

13. AZIMUTHAL QUANTUM NUMBER
 The second quantum number, known as the
angular or orbital quantum number, describes
the subshell and gives the magnitude of the
orbital angular momentum through the relation.
In chemistry and spectroscopy, ℓ = 0 is called an s
orbital, ℓ = 1 a p orbital, ℓ = 2 a d orbital, and ℓ =
3 an f orbital. The value of ℓ ranges from 0 to n −
1 because the first p orbital (ℓ = 1) appears in the
second electron shell (n = 2), the first d orbital (ℓ
= 2) appears in the third shell (n = 3), and so on

14. MAGNETIC QUANTUM NUMBER
 The magnetic quantum number describes the energy
levels available within a subshell and yields the projection
of the orbital angular momentum along a specified axis.
The values of mℓ range from − l to ℓ, with integer steps
between them. The s subshell (ℓ = 0) contains one orbital,
and therefore the mℓ of an electron in an S subshell will
always be 0. The p subshell (ℓ = 1) contains three orbitals
(in some systems depicted as three “dumbbell-shaped”
clouds), so the mℓ of an electron in a p subshell will be −1,
0, or 1. The d subshell (ℓ = 2) contains five orbitals, with
mℓ values of −2, −1, 0, 1, and 2. The value of the
mℓ quantum number is associated with the orbital
orientation.

15. SPIN QUANTUM NUMBER
The fourth quantum number describes the spin
(intrinsic angular momentum) of the electron within
that orbital and gives the projection of the spin angular
momentum (s) along the specified axis. Analogously,
the values of ms range from −s to s, where s is the spin
quantum number, an intrinsic property of particles. An
electron has spin s = ½, consequently ms will be ±,
corresponding with spin and opposite spin. Each
electron in any individual orbital must have different
spins because of the Pauli exclusion principle,
therefore an orbital never contains more than two
electrons.

16. FOUR QUANTUM NUMBERS

17. RULES GOVERNING FILLING OF
ELECTRONS IN THE ORBITAL

18. RULES GOVERNING FILLING OF
ELECTRONIC CONFIGURATION
WRITING
Aufbau Principle
• This principle is named after the German word
‘Aufbeen’ which means ‘build up’.
• The Aufbau principle dictates that electrons will occupy
the orbitals having lower energies before occupying
higher energy orbitals.
• The energy of an orbital is calculated by the sum of the
principal and the azimuthal quantum numbers.
• According to this principle, electrons are filled in the
following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p,
6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p

19. DEMONSTRATION OF ENERGY LEVELS

20. SEQUENCE OF FILLING ATOMIC
ORBITAL

21. RULES GOVERNING OF ELECTRONIC
CONFIGURATION WRITING
 It is important to note that there exist many
exceptions to the Aufbau principle such as
chromium and copper. These exceptions can
sometimes be explained by the stability
provided by half-filled or completely filled
subshells.

22. RULES GOVERNING ELECTRONIC
CONFIGURATION WRITING
Pauli exclusion principle
 states that a maximum of two electrons, each
having opposite spins, can fit in an orbital.
 This principle can also be stated as “no two
electrons in the same atom have the same
values for all four quantum numbers”.
 Therefore, if the principal, azimuthal, and
magnetic numbers are the same for two
electrons, they must have opposite spins.

23. RULES GOVERNING ELECTRONIC
CONFIGURATION WRITING
Hund’s Rule
 This rule describes the order in which electrons
are filled in all the orbitals belonging to a
subshell.
 It states that every orbital in a given subshell is
singly occupied by electrons before a second
electron is filled in an orbital.
 In order to maximize the total spin, the electrons
in the orbitals that only contain one electron all
have the same spin (or the same values of the
spin quantum number)

24. WRITING ELCECTRONIC
CONFIGURATION OF ATOMS

25. WRITING ELECTRONIC
CONFIGURATION

26. WRITING ELECTRONIC
CONFIGURATION

27. HINT

28. END OF SESSION
HAPPY STUDYING , BEST REGARDS