Notebook
3
[Source: Inštrukcije blog, 2025]
STRUCTURE OF MOLECULES OF ORGANIC
COMPOUNDS
Atomic Bonding and Molecular Geometry
Mastery of Electron Configuration & Hybridization in Organic Chemistry
,SUMMARY OF CONTENT
1 Summary of Content
These notes provide a comprehensive guide to electron configuration, hybridization,
and chemical bonding in organic chemistry.
2 Brief Description
This structured study aid covers the foundations of general and organic chemistry—
from atomic structure to complex molecular frameworks. It includes theoretical
explanations, visual diagrams, and solved practical examples from renowned
academic sources (Brenčič, Lazarini, Drofenik, Graunar).
3 What will students learn?
1. Electron Configuration and Atomic Structure:
• Understanding the rules governing electron distribution: Aufbau principle,
Pauli exclusion principle, and Hund’s rule.
• Writing full and abbreviated configurations (using noble gas cores) for elements
such as carbon, nitrogen, oxygen, and fluorine.
• The significance of valence electrons in reactivity and their role in the human
body.
2. Chemical Bond Theory:
• The difference between σ (sigma) and π (pi) bonds: how they form and which
is stronger.
• Understanding covalent bonding and deviations from standard rules.
• Identifying atomic orbital overlaps.
3. Hybridization of Carbon Atoms (sp3, sp2, sp):
• Detailed explanations of hybrid orbital formation with visual diagrams.
• The connection between hybridization type and molecular geometry
(tetrahedral, trigonal planar, linear).
• Determining hybridization in complex structures: alkanes, alkenes, alkynes,
benzene rings, carboxylic acids, and ketones.
4. Geometry and Spatial Arrangement:
• Predicting bond angles (109.5°, 120°, 180°) based on hybridization.
• Analysis of skeletal, condensed, and stereochemical formulas.
• Interpreting ball-and-stick molecular models (e.g., but-2-yne).
4 Why choose these notes?
,• Practical Examples: Includes 23 specific solved problems that frequently
appear in textbooks and exams.
• Visual Aid: Hand-drawn sketches of orbitals and molecules that simplify the
understanding of 3D structures.
• Verified Sources: Based on literature used in high schools and universities.
,TABLE OF CONTENTS
1 THEORY .............................................................................................................. 1
2 TASKS ................................................................................................................. 7
3 TASKS OF SOLUTIONS ................................................................................... 14
4 LITERATURE AND SOURCES ......................................................................... 35
APPENDICES ........................................................................................................... 37
,TABLE OF FIGURES
Image 1: Shapes of atomic orbitals 1
Image 2: Comparison of 1s and 2s orbital sizes 2
Image 3: Example of single σ-bonds in an ethane molecule 4
Image 4: Example of a double bond (σ and π) in an ethene molecule 4
Image 5: Formation of two sp hybrid orbitals 5
Image 6: Formation of three sp2 hybrid orbitals with trigonal planar geometry 5
Image 7: Formation of four sp3 hybrid orbitals with tetrahedral geometry 5
, Organic chemistry notes
1 THEORY
Electron Configuration and Orbitals
To understand chemistry, the key elements are electron configuration and orbitals.*
The behavior of elements and the way they form bonds during chemical reactions
depend directly on their electron configuration. This configuration describes the
arrangement of electrons within atomic orbitals and represents a notation system that
reveals how atoms interact with one another.
The primary tool for this is the periodic table, which is not just a list of substances but
a tool that shows us the energy level of an atom. Based on this information, we can
correctly arrange electrons within the atom, while following three fundamental rules:
1. Aufbau Principle: Electrons first fill the orbitals with the lowest energy.
2. Pauli Exclusion Principle: States that no two electrons in the same atom can
have the same four quantum numbers, meaning they must differ in their spin
(indicated in diagrams by opposite arrows).
3. Hund's Rule: Electrons occupy orbitals of the same subshell individually first,
before they begin to pair up.
Source: Blog inštruktorjev, 2025
Explanation of the terms*
→ Orbitals
An orbital is a region around the atomic nucleus where there is approximately a 95%
probability of finding an electron. Orbitals differ from one another in energy, size, and
shape (s, p, d, and f) — see the figure 1.
Figure 1: Shapes of atomic orbitals
Source: Elatform, 2020
1
, Organic chemistry notes
• Energy and Excited State: Electrons in a 2s orbital have lower energy than
electrons in a 2p orbital. Atoms are usually found in the ground state, which
has the lowest possible energy. If an atom absorbs energy (e.g., light or heat),
its electrons move to higher energy levels, known as the excited state.
• Orbital Size: Size depends on the energy level ("floor"). For example, the 1s
orbital in the first energy level is smaller than the 2s orbital in the second level
(Figure 2).
• Chemical Properties: The shape, occupancy, and energy of orbitals strongly
influence how atoms form bonds and react.
Figure 2: Comparison of 1s and 2s orbital sizes
Source: Chemistrysaanguyen.com, 2026
Orbital Capacity
Each type of orbital has a limited capacity. Each "room" (the square in a diagram) can
hold a maximum of two electrons with opposite spins.
s orbitals: 1 "room" → maximum of 2 electrons (1 x 2).
p orbitals: 3 "rooms" (px, py, pz) → maximum of 6 electrons
(3 x 2).
d orbitals: 5 "rooms" → maximum of 10 electrons (5 x 2).
f orbitals: 7 "rooms" → maximum of 14 electrons (7 x 2).
FORMULA:
Maximum number of electrons = Number of orbitals (rooms) x 2
Orbital Diagram
The sequence of filling orbitals can be imagined as building a structure from the ground
up.
2
3
[Source: Inštrukcije blog, 2025]
STRUCTURE OF MOLECULES OF ORGANIC
COMPOUNDS
Atomic Bonding and Molecular Geometry
Mastery of Electron Configuration & Hybridization in Organic Chemistry
,SUMMARY OF CONTENT
1 Summary of Content
These notes provide a comprehensive guide to electron configuration, hybridization,
and chemical bonding in organic chemistry.
2 Brief Description
This structured study aid covers the foundations of general and organic chemistry—
from atomic structure to complex molecular frameworks. It includes theoretical
explanations, visual diagrams, and solved practical examples from renowned
academic sources (Brenčič, Lazarini, Drofenik, Graunar).
3 What will students learn?
1. Electron Configuration and Atomic Structure:
• Understanding the rules governing electron distribution: Aufbau principle,
Pauli exclusion principle, and Hund’s rule.
• Writing full and abbreviated configurations (using noble gas cores) for elements
such as carbon, nitrogen, oxygen, and fluorine.
• The significance of valence electrons in reactivity and their role in the human
body.
2. Chemical Bond Theory:
• The difference between σ (sigma) and π (pi) bonds: how they form and which
is stronger.
• Understanding covalent bonding and deviations from standard rules.
• Identifying atomic orbital overlaps.
3. Hybridization of Carbon Atoms (sp3, sp2, sp):
• Detailed explanations of hybrid orbital formation with visual diagrams.
• The connection between hybridization type and molecular geometry
(tetrahedral, trigonal planar, linear).
• Determining hybridization in complex structures: alkanes, alkenes, alkynes,
benzene rings, carboxylic acids, and ketones.
4. Geometry and Spatial Arrangement:
• Predicting bond angles (109.5°, 120°, 180°) based on hybridization.
• Analysis of skeletal, condensed, and stereochemical formulas.
• Interpreting ball-and-stick molecular models (e.g., but-2-yne).
4 Why choose these notes?
,• Practical Examples: Includes 23 specific solved problems that frequently
appear in textbooks and exams.
• Visual Aid: Hand-drawn sketches of orbitals and molecules that simplify the
understanding of 3D structures.
• Verified Sources: Based on literature used in high schools and universities.
,TABLE OF CONTENTS
1 THEORY .............................................................................................................. 1
2 TASKS ................................................................................................................. 7
3 TASKS OF SOLUTIONS ................................................................................... 14
4 LITERATURE AND SOURCES ......................................................................... 35
APPENDICES ........................................................................................................... 37
,TABLE OF FIGURES
Image 1: Shapes of atomic orbitals 1
Image 2: Comparison of 1s and 2s orbital sizes 2
Image 3: Example of single σ-bonds in an ethane molecule 4
Image 4: Example of a double bond (σ and π) in an ethene molecule 4
Image 5: Formation of two sp hybrid orbitals 5
Image 6: Formation of three sp2 hybrid orbitals with trigonal planar geometry 5
Image 7: Formation of four sp3 hybrid orbitals with tetrahedral geometry 5
, Organic chemistry notes
1 THEORY
Electron Configuration and Orbitals
To understand chemistry, the key elements are electron configuration and orbitals.*
The behavior of elements and the way they form bonds during chemical reactions
depend directly on their electron configuration. This configuration describes the
arrangement of electrons within atomic orbitals and represents a notation system that
reveals how atoms interact with one another.
The primary tool for this is the periodic table, which is not just a list of substances but
a tool that shows us the energy level of an atom. Based on this information, we can
correctly arrange electrons within the atom, while following three fundamental rules:
1. Aufbau Principle: Electrons first fill the orbitals with the lowest energy.
2. Pauli Exclusion Principle: States that no two electrons in the same atom can
have the same four quantum numbers, meaning they must differ in their spin
(indicated in diagrams by opposite arrows).
3. Hund's Rule: Electrons occupy orbitals of the same subshell individually first,
before they begin to pair up.
Source: Blog inštruktorjev, 2025
Explanation of the terms*
→ Orbitals
An orbital is a region around the atomic nucleus where there is approximately a 95%
probability of finding an electron. Orbitals differ from one another in energy, size, and
shape (s, p, d, and f) — see the figure 1.
Figure 1: Shapes of atomic orbitals
Source: Elatform, 2020
1
, Organic chemistry notes
• Energy and Excited State: Electrons in a 2s orbital have lower energy than
electrons in a 2p orbital. Atoms are usually found in the ground state, which
has the lowest possible energy. If an atom absorbs energy (e.g., light or heat),
its electrons move to higher energy levels, known as the excited state.
• Orbital Size: Size depends on the energy level ("floor"). For example, the 1s
orbital in the first energy level is smaller than the 2s orbital in the second level
(Figure 2).
• Chemical Properties: The shape, occupancy, and energy of orbitals strongly
influence how atoms form bonds and react.
Figure 2: Comparison of 1s and 2s orbital sizes
Source: Chemistrysaanguyen.com, 2026
Orbital Capacity
Each type of orbital has a limited capacity. Each "room" (the square in a diagram) can
hold a maximum of two electrons with opposite spins.
s orbitals: 1 "room" → maximum of 2 electrons (1 x 2).
p orbitals: 3 "rooms" (px, py, pz) → maximum of 6 electrons
(3 x 2).
d orbitals: 5 "rooms" → maximum of 10 electrons (5 x 2).
f orbitals: 7 "rooms" → maximum of 14 electrons (7 x 2).
FORMULA:
Maximum number of electrons = Number of orbitals (rooms) x 2
Orbital Diagram
The sequence of filling orbitals can be imagined as building a structure from the ground
up.
2
