Notebook 4
[Source: Inštrukcije blog, 2025]
STRUCTURE OF MOLECULES OF
ORGANIC COMPOUNDS
Molecular Models and Types of Formulas of
Organic Compounds
,SUMMARY OF CONTENT
Comprehensive Guide to Organic Chemistry Structures & Geometry
Course Overview
This study guide offers a systematic, step-by-step approach to mastering the
visualization and notation of organic compounds. It bridges the gap between abstract
2D formulas and 3D molecular reality, making it an essential resource for students
preparing for chemistry exams or international certifications.
What is Included in These Notes?
• Structural Notation Mastery: Detailed exercises on converting between
various chemical representations, including ball-and-stick models, full
structural formulas, condensed (rational) formulas, and skeletal drawings.
• Deciphering Linear Formulas: A clear breakdown of complex linear notations,
including the use of parentheses, multipliers, and terminal group orientations
(e.g., the logic behind HOCH3 vs. CH3OH notation).
• Molecular & Empirical Formula Derivation: Proven methods for counting
atoms in skeletal structures and calculating the Empirical Formula using the
Greatest Common Divisor (GCD) method.
• VSEPR Theory & Spatial Geometry: Expert guidance on identifying molecular
shapes based on bond types:
o Tetrahedral (4 single bonds, ≈ 109.5°)
o Trigonal Planar (1 double + 2 single bonds, ≈ 120°)
o Linear (1 triple + 1 single bond, 180°)
• Advanced Bonding Analysis: Practical exercises on identifying and counting
σ (sigma) and π (pi) bonds in complex polycyclic and unsaturated molecules.
Why Choose This Guide?
1. Dual-Language Precision: Although the notes are in English, they are
designed with clarity in mind, ensuring all technical terms are used accurately.
, 2. Visual Learning Aids: Includes custom-drawn "Spatial Formulas" that show
the exact 3D orientation of atoms—something missing from standard textbooks.
3. Exam-Oriented Practice: Contains 19 high-quality examples with detailed
"Notes" and "Tips" to help you avoid the most common student mistakes.
4. Verified Sources: Problems are curated from reputable chemistry literature
(Graunar, Slapničar), ensuring academic rigor.
Perfect for:
• High school students (Chemistry)
• Pre-university / A-Level students
• Undergraduate beginners in Organic Chemistry
,TABLE OF CONTENTS
1 THEORY .............................................................................................................. 1
2 TASKS ............................................................................................................... 10
3 TASKS OF SOLUTIONS ................................................................................... 16
4 LITERATURE AND SOURCES ......................................................................... 26
APPENDICES ........................................................................................................... 27
,TABLE OF FIGURES
Image 1: Ball-and-stick model of methane 1
Image 2: Space-filling (Calotte) model of methane 2
Image 3: Stick or wireframe model of methane 2
Image 4: 2-butanol 4
,TABLE OF TABLES
Table 1: Comparison of Molecular Models.................................................................. 4
, Organic chemistry notes
1 THEORY
Identifying Molecular Models in Organic Chemistry
In organic chemistry, molecules of organic compounds are represented using various
models that help us understand their three-dimensional structure. In chemistry
education, ball-and-stick, space-filling, and wireframe models are the most
commonly used.
Source: Ekemija, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
Comparing different models of the methane molecule (CH4) - See Figures 1, 2,
and 3:
1. Ball-and-Stick Model
Figure 1: Ball-and-stick model of methane
Source: Own work, 2026
This model is the most widely used educational tool for understanding molecular
geometry.
• Structure: Atoms are represented by spheres of different colors and sizes,
while chemical bonds are represented by sticks.
• Advantages: Provides an extremely clear visualization of the spatial
arrangement of atoms, types of bonds (single, double, triple), and the angles
between them.
• Characteristics: The size ratio of the spheres corresponds to the actual relative
sizes of the atoms.
• Limitation: It does not fully reflect the true shape of the molecule, as the atoms
(due to the sticks) are shown too far apart.
Source: Ekemija, 2026; Openprof, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
1
, Organic chemistry notes
2. Space-filling Model
Figure 2: Space-filling (Calotte) model of methane
Source: Own work, 2026
This model provides the best insight into the physical presence of a molecule in space.
• Structure: Atoms are shown as spheres that partially overlap one another.
• Advantages: Accurately illustrates the actual volume, size, and shape of the
molecule (the so-called Van der Waals volume).
• Disadvantage: Due to its compact structure, bond angles and internal details
are less visible.
Source: Ekemija, 2026; Openprof, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
3. Wireframe (or Stick) Model
Figure 3: Stick or wireframe model of methane
Source: Own work, 2026
Primarily used for visualizing large and complex molecular structures.
• Structure: Atoms are merely nodes (junctions), while the emphasis is on the
lines or tubes representing the bonds.
• Advantages: Allows for a clear overview of the molecular skeleton. The image
is not cluttered, which is crucial when displaying complex molecules (e.g.,
proteins).
Source: Openprof, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
2
[Source: Inštrukcije blog, 2025]
STRUCTURE OF MOLECULES OF
ORGANIC COMPOUNDS
Molecular Models and Types of Formulas of
Organic Compounds
,SUMMARY OF CONTENT
Comprehensive Guide to Organic Chemistry Structures & Geometry
Course Overview
This study guide offers a systematic, step-by-step approach to mastering the
visualization and notation of organic compounds. It bridges the gap between abstract
2D formulas and 3D molecular reality, making it an essential resource for students
preparing for chemistry exams or international certifications.
What is Included in These Notes?
• Structural Notation Mastery: Detailed exercises on converting between
various chemical representations, including ball-and-stick models, full
structural formulas, condensed (rational) formulas, and skeletal drawings.
• Deciphering Linear Formulas: A clear breakdown of complex linear notations,
including the use of parentheses, multipliers, and terminal group orientations
(e.g., the logic behind HOCH3 vs. CH3OH notation).
• Molecular & Empirical Formula Derivation: Proven methods for counting
atoms in skeletal structures and calculating the Empirical Formula using the
Greatest Common Divisor (GCD) method.
• VSEPR Theory & Spatial Geometry: Expert guidance on identifying molecular
shapes based on bond types:
o Tetrahedral (4 single bonds, ≈ 109.5°)
o Trigonal Planar (1 double + 2 single bonds, ≈ 120°)
o Linear (1 triple + 1 single bond, 180°)
• Advanced Bonding Analysis: Practical exercises on identifying and counting
σ (sigma) and π (pi) bonds in complex polycyclic and unsaturated molecules.
Why Choose This Guide?
1. Dual-Language Precision: Although the notes are in English, they are
designed with clarity in mind, ensuring all technical terms are used accurately.
, 2. Visual Learning Aids: Includes custom-drawn "Spatial Formulas" that show
the exact 3D orientation of atoms—something missing from standard textbooks.
3. Exam-Oriented Practice: Contains 19 high-quality examples with detailed
"Notes" and "Tips" to help you avoid the most common student mistakes.
4. Verified Sources: Problems are curated from reputable chemistry literature
(Graunar, Slapničar), ensuring academic rigor.
Perfect for:
• High school students (Chemistry)
• Pre-university / A-Level students
• Undergraduate beginners in Organic Chemistry
,TABLE OF CONTENTS
1 THEORY .............................................................................................................. 1
2 TASKS ............................................................................................................... 10
3 TASKS OF SOLUTIONS ................................................................................... 16
4 LITERATURE AND SOURCES ......................................................................... 26
APPENDICES ........................................................................................................... 27
,TABLE OF FIGURES
Image 1: Ball-and-stick model of methane 1
Image 2: Space-filling (Calotte) model of methane 2
Image 3: Stick or wireframe model of methane 2
Image 4: 2-butanol 4
,TABLE OF TABLES
Table 1: Comparison of Molecular Models.................................................................. 4
, Organic chemistry notes
1 THEORY
Identifying Molecular Models in Organic Chemistry
In organic chemistry, molecules of organic compounds are represented using various
models that help us understand their three-dimensional structure. In chemistry
education, ball-and-stick, space-filling, and wireframe models are the most
commonly used.
Source: Ekemija, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
Comparing different models of the methane molecule (CH4) - See Figures 1, 2,
and 3:
1. Ball-and-Stick Model
Figure 1: Ball-and-stick model of methane
Source: Own work, 2026
This model is the most widely used educational tool for understanding molecular
geometry.
• Structure: Atoms are represented by spheres of different colors and sizes,
while chemical bonds are represented by sticks.
• Advantages: Provides an extremely clear visualization of the spatial
arrangement of atoms, types of bonds (single, double, triple), and the angles
between them.
• Characteristics: The size ratio of the spheres corresponds to the actual relative
sizes of the atoms.
• Limitation: It does not fully reflect the true shape of the molecule, as the atoms
(due to the sticks) are shown too far apart.
Source: Ekemija, 2026; Openprof, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
1
, Organic chemistry notes
2. Space-filling Model
Figure 2: Space-filling (Calotte) model of methane
Source: Own work, 2026
This model provides the best insight into the physical presence of a molecule in space.
• Structure: Atoms are shown as spheres that partially overlap one another.
• Advantages: Accurately illustrates the actual volume, size, and shape of the
molecule (the so-called Van der Waals volume).
• Disadvantage: Due to its compact structure, bond angles and internal details
are less visible.
Source: Ekemija, 2026; Openprof, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
3. Wireframe (or Stick) Model
Figure 3: Stick or wireframe model of methane
Source: Own work, 2026
Primarily used for visualizing large and complex molecular structures.
• Structure: Atoms are merely nodes (junctions), while the emphasis is on the
lines or tubes representing the bonds.
• Advantages: Allows for a clear overview of the molecular skeleton. The image
is not cluttered, which is crucial when displaying complex molecules (e.g.,
proteins).
Source: Openprof, 2026; Slapničar, M., Godec, M., Dlouhy, M., 2025
2
