The document is an activity sheet for a General Chemistry 1 course that describes electrons using quantum numbers. It defines the four quantum numbers - principal quantum number (n), azimuthal quantum number (l), magnetic quantum number (ml), and spin quantum number (ms). The activity sheet provides background information on these quantum numbers and their possible values. It then gives students activities to practice determining quantum number values and identifying subshell locations based on given quantum numbers.

1. i
General Chemistry 1
Activity Sheet
Quarter 2 – MELC 1
Week 1
Quantum Mechanical Description
of Electrons
REGION VI – WESTERN VISAYAS
SHS

2. ii
Development Team of Activity Sheet
Writers: Writer: Joselyn C. Valenciano
Editor: Moonyeen C. Rivera
Layout Artists: Mara Jamaica B. Floreno and Kris Dawn C. Rivera
Schools Division Quality Assurance Team:
Analie J. Lobaton
Moonyeen C. Rivera,
Division of Cadiz City Management Team:
Ma. Lorlinie M. Ortillo,
May P. Pascual
Moonyeen C. Rivera,
Analie J. Lobaton
Regional Management Team:
Ma. Gemma M. Ledesma
Josilyn S. Solana
Elena P. Gonzaga
Donald T. Genine
Rovel R. Salcedo,
Moonyeen C. Rivera,
Anita S. Gubalane,
Minda L. Soldevilla,
Daisy L. Lopez,
Joseph M. Pagalaran
General Chemistry 1
Activity Sheet No. 1: Quantum Mechanical Description of Electrons
First Edition, 2020
Published in the Philippines
By the Department of Education
Region 6 – Western Visayas
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ALL RIGHTS RESERVED. No part of this learning resource may be reproduced or
transmitted in any form or by any means electronic or mechanical without written permission
from the DepEd Regional Office 6 – Western Visayas.

3. iii
Introductory Message
Welcome to General Chemistry 1!
The Learning Activity Sheet is a product of the collaborative efforts of the
Schools Division of Cadiz City and DepEd Regional Office VI - Western Visayas
through the Curriculum and Learning Management Division (CLMD). This is
developed to guide the learning facilitators (teachers, parents and responsible
adults) in helping the learners meet the standards set by the K to 12 Basic Education
Curriculum.
The Learning Activity Sheet is self-directed instructional materials aimed to
guide the learners in accomplishing activities at their own pace and time using the
contextualized resources in the community. This will also assist the learners in
acquiring the lifelong learning skills, knowledge and attitudes for productivity and
employment.
For learning facilitator:
The General Chemistry 1 Activity Sheet will help you facilitate the leaching-
learning activities specified in each Most Essential Learning Competency (MELC) with
minimal or no face-to-face encounter between you and learner. This will be made available
to the learners with the references/links to ease the independent learning.
For the learner:
The General Chemistry 1 Activity Sheet is developed to help you continue learning
even if you are not in school. This learning material provides you with meaningful and
engaging activities for independent learning. Being an active learner, carefully read and
understand the instructions then perform the activities and answer the assessments. This
will be returned to your facilitator on the agreed schedule.

5. 1
Name of Learner:____________________________________________________
Grade and Section:___________________________________Date: __________
General Chemistry 1 Activity Sheet No. 1
Quantum Mechanical Description of Electrons
I. Learning Competency with Code
Use quantum numbers to describe an electron in an atom
(STEM_GC11ESIIa-b-54)
Support Competencies:
1. Identify the 4 quantum numbers used to quantum mechanically describe an
electron
2. Determine the possible values of a quantum number given the value of other
quantum numbers
3. Identify the subshell location of an electron given a set of quantum numbers
II. Background Information for Learners
Heisenberg’s Uncertainty Principle states that it is not possible to determine
both the momentum (angular velocity) and the position of a particle (such as an
electron) at the same time. The more certain you are of one value, the more uncertain
you are of the other.
In Grade 9, you have learned about the Bohr’s Model where an electron can
be visualized as a moving “particle” in an orbit around the nucleus of an atom. The
model, however, is primitive and less dependable since it was found out that electrons
behave both as a “particle” and a “wave”. Thus, it does not move around a steady
circular orbit but in a region of 3-Dimensional shape. The modern day model of an
atom is called “cloud model” or “quantum model” which is grounded on Heisenberg’s
Uncertainty Principle. The illustration below compares the two models.
THE FOUR QUANTUM NUMBERS
Erwin Schrodinger, the physicist who introduced the Wave Theory, together with
other scientists found out that a set of numbers are needed to describe the three-
dimensional coordinates of an electron in the atomic orbitals of a hydrogen atom.
These numbers are called QUANTUM NUMBERS.
e-
r
e-
e- e-
e-
e-
e-
e-
e-
e-
e-
Not an exact location
of the electron but the
probability density of
electron position. Also
known as “electron
cloud”
Fig. 1: Bohr’s Model Fig. 2: Quantum/Cloud Model
e-
e-
e-
e-
e-
e-
e-
e-
e-
e-

6. 2
Principal Quantum Number
(n)
• This represents the energy level of the
electron in question.
• When n = 1, the electron is on 1st energy
level, and so on.
• The larger the “n” value, the higher the
energy level, the farther is the electron
from the nucleus and the bigger is the
atom.
Angular Momentum Quantum
Number or the Azimuthal QN
(ℓ)
• Tells us the Atomic Orbital Shape.
• Each principal number is called a shell
which is a collection of orbitals
containing electron of the same energy
level.
• Within each shell is a subshell which is
a subdivision of orbitals following a
specific electron cloud shape.
• There are four known subshells s, p, d
and f.
• These subshells are designated to the
value of ℓ.
• The values of ℓ range from 0 to (n – 1).
So if n = 2, then ℓ can be either equal to
0 or 1.
Value of ℓ Subshell No. of Orbitals
0 s 2
1 p 3
2 d 5
3 f 7
Magnetic Quantum Number
(mℓ)
• Tells about the orientation of the atomic
orbitals along the xyz plane (a three-
dimensional coordinate plane).
• The range of valuesfor mℓ = - ℓ, ..., 0,…,+
ℓ .
• So if ℓ = 1, then mℓ = -1, 0, +1.
• Notice that there are three values for mℓ .
It means that in the p-subshell (ℓ = 1)
there are 3 orbitals with different
orientations along the xyz plane.
• One orbital is oriented towards mℓ = -1,
another on mℓ = 0, and another towards
mℓ = +1.
Spin Quantum Number
(ms)
• Gilbert Lewis had first proposed that
electrons in an orbital come in pairs.
• However, these electrons cannot have
the same set of Quantum Numbers as it
was found out that pairs of electrons
have different angular momentum as an
effect of magnetic field created by two
spinning electrons.

7. 3
• This quantum number describes the spin
or angular momentum of the electron pair
in an orbital.
• The spin of electrons can only be either
in clockwise of counterclockwise
direction, or up spin and down spin and
represented by numbers +1/2 and -1/2.
(more of this explanation in the next
lesson on electron configuration).
Orbital Shapes
Numbers and letters are used to name subshells.
Example:
Summary Table of the Possible Values of 4 Quantum Numbers
Principal QN
(n) = 2
Azimuthal
QN (ℓ) = 1
Table from https://courses.lumenlearning.com
2p Subshell

8. 4
III. Activity Proper
Activity 1
Directions: Write down the possible values of the missing quantum number. Write
your answer on a sheet of paper.
n ℓ mℓ ms
3 0,1,2 -2,-1,0,1,2 +1/2, -1/2
4 +1/2, -1/2
2 +1/2, -1/2
1 +1/2, -1/2
Activity 2
Directions: Read and understand the situations below and answer the question that
follows. Write your answer on a sheet of paper.
1. Write down the possible values of n, ℓ, and mℓ for an electron in the 2p
subshell.
n ℓ mℓ
2. How many orbitals can be associated with n=3?
______________________________________________________________
3. Can an electron be described by the following set of quantum numbers? If not,
identify which quantum number value is invalid, and briefly explain why: n=2,
ℓ=2, mℓ=0, ms= -1/2
______________________________________________________________
4. Can an electron be described by the following set of quantum numbers? If not,
identify which quantum number value is invalid, and briefly explain why: n=4,
ℓ=2, mℓ=2, ms= -1/2
______________________________________________________________
5. Can an electron be described by the following set of quantum numbers? If not,
identify which quantum number value is invalid, and briefly explain why: n=4,
ℓ= -3, mℓ=4, ms= +1/2
______________________________________________________________

9. 5
Activity 3: Given the following set of quantum numbers, identify the Subshell in which
the electron is located. If one of the value makes the set of numbers invalid, write
“INVALID” on the column for Subshells. The first one is done for you.
n ℓ mℓ Subshell
2 0 0 2s
3 1 1
2 1 -2
4 3 -1
1 0 1
4 5 -3
IV. Reflection
Complete the statements below.
I understand
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
I don’t understand
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
I need more information about
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

10. 6
V. Answer Key
Activity
1
n
ℓ
m
ℓ
m
s
3
0,1,2
-2,-1,0,1,2
+
1/2,
-
1/2
4
0,1,2,3
-3,-2,-1,0,1,2,3
+
1/2,
-
1/2
2
0,1
-1,0,1
+
1/2,
-
1/2
1
0
0
+
1/2,
-
1/2
Activity
2
1.
n
ℓ
m
ℓ
2
0,1
-1,0,1
2.
5
orbitals
3.
No,
because
ℓ=2
is
invalid.
Possible
values
of
ℓ
are
-1,0
and
1
4.
Yes
5.
No,
because
m
ℓ
=
4
is
invalid.
Possible
values
of
m
ℓ
are
-3,-2,-1,0,1,2,
and
3.
Activity
3
n
ℓ
m
ℓ
Orbital
2
0
0
2s
3
1
1
3p
2
1
-2
invalid
4
3
-1
4f
1
0
1
invalid
4
5
-3
invalid
3
2
2
3d
1
0
0
1s
2
1
0
2p
4
3
-4
invalid

11. 7
VI. Links and/or Other References
Moore, John, Conrad Stanitski, Peter Jurs, Mark Cracolice, and Ed Peters.
"Beyond The Bohr Model: The Quantum Mechanical Model Of The
Atom." In General Chemistry 1, 138-149. Manila: Rex Bookstore Inc.,
2019.
"Quantum Numbers for Atoms." Chemistry LibreTexts. Last modified August 15, 2020.
https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook
_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Quantum_Mech
anics/10%3A_Multi-electron_Atoms/Quantum_Numbers_for_Atoms.
"Quantum Numbers | Introduction to Chemistry." Lumen Learning – Simple Book Production.
Accessed November 12, 2020.
https://courses.lumenlearning.com/introchem/chapter/quantum-numbers/.
"What is Hybridization in Organic Chemistry." Info-Science (blog). February 10, 2016.
https://theinfoscience.blogspot.com/2016/02/what-is-hybridization-in-organic.html.