The presentation can be a remedial lesson on the topic "electronic structure of matter" grade 9, science second quarter

1. CHARACTERIZING THE
ELECTRONS
MA. RACHEL B. ESPINO
BUHATAN NATIONAL HIGH
SCHOOL
SORSOGON CITY

2.  The detailed knowledge of electron
behaviour is essential since the
characteristics of an element depends
on the electron arrangement.

3. Atomic Orbital
 An atomic orbital is the volume or region of space
around the nucleus where the electron being
described is most likely to be found.

4. Each atomic orbital is
characterized by:
 Energy
 Shape
 Orientation in space
 Direction of electron spin

5. Energy
 The electron energy relates to the size of
the atomic orbital.
 The farther the distance of the electron
from nucleus, the higher the distance of
the electron from the nucleus, the bigger is
the size of the atomic orbital and greater is
its energy.
HYDROGEN
LITHIU
M SODIU
M
POTASSIU

6.  The main energy level (designated by the
number “n”) where the orbital is found is
designated by numbers (n = 1, 2, 3, 4, 5, 6, 7)
or letters (K, L, M, N, O, P, Q).
 The number n is often referred to as principal
quantum number. So far, all known elements
have only enough electrons to occupy 7 main
energy levels.
n = 1 2 3 4 5 6 7
K L M N O P Q

7. Shapes
 There are four different kinds of atomic
orbital based on shapes. Each kind is
distinguished by a second quantum
number designated by l.
 The quantum number l could take values
from zero to n - 1. They are referred to as s
( l = 0), p ( l = 1), d ( l = 2) and f ( l = 3).
These kinds of orbital (s,p,d,f ) are referred
to as sublevels in each main energy level.

8.  The main energy level in an atom actually
consists of sublevels of energy. It means
that although a number of electrons may be
found in the same main energy level, they
may actually be found in different sublevels
of energy. It means, electrons in a particular
main energy level do not really possess the
same amount of energy.

10. Orientation in Space and
Direction of Electron Spin

11. Pauli’s Exclusion Principle
 Pauli’s Exclusion
Principle states that an
orbital cannot hold
more than 2 electrons
(Wolfgang Pauli, 1925)

12. The Pauli’s Exclusion Principle is
based on the following theories:
1. An electron
exhibits a spin:
clockwise or
counterclockwise
.

13. 2. When 2 electrons of opposite spins are
spinning or rapidly whirling in space, they
set up opposite magnetic fields which
attracts one another. This explains why only
2 electrons can occupy the same orbital.
Electrons with the same spin repel each
other.

14. 3. A third electron
will spin in a
direction similar
to either one of
the two
electrons in an
orbital, as a
result it will be
repelled or
pushed away
by the electron
with same spin.

15. Aufbau Principle
 Aufbau Principle states that as soon as
an energy level is filled up with electrons,
any additional electron is thrown to the
next outer or higher energy level.
(formulated by Neils Bohr and Wolfgang
Pauli in the 1920s).

17. Hund’s Rule
 Hund’s Rule states
that electrons occupy
separate orbital in the
same subshell with
parallel spins first
before pairing
(Friedrich Hund, 1927)

18. Electronic
Configuration

19.  The number or distribution or arrangement
of electrons in the energy levels of a
particular atom of an element. Example is
the electron configuration of helium
demonstrated below:
1
2
Main Energy
level
Orbital/ sublevel
No. of
electron in
the sublevel

20.  We use the periodic table to identify the
main energy levels and sublevels

22. From the electron
configuration, we can
now presume the
arrangement of the
electrons in an element.
For xample sodium.

24. References:
 Chemistry: Science and Technology Textbook for
Third Year. Quezon City: Vibal Publishing House,
2009.
 Chemistry Textbook in Science and Technology
Third Year. Quezon City: SD Publications, Inc.,
2001.
 www.wikipedia.com