Chemical Bonding and Shapes of Molecules - Chemistry (Undergraduate Foundation)

This course covers the principles that govern how atoms connect to form molecules. It provides a full treatment of ionic and covalent bonding, valence forces, and the various types of intermolecular forces, including hydrogen bonding. The core of the course is a practical guide to predicting the three-dimensional shape of molecules using VSEPR theory and the concept of orbital hybridization. A command of chemical bonding and molecular geometry is essential for understanding the properties and reactivity of all chemical substances. The shape of a molecule dictates its function, from the specificity of drug-receptor interactions in medicine to the properties of polymers in materials science. This is the foundational knowledge for designing new molecules and materials. By the end of this course, you will be able to draw Lewis structures for any molecule, predict its three-dimensional geometry and bond angles using VSEPR theory, and determine its polarity. You will also be able to explain the formation of sigma and pi bonds using the concept of orbital hybridization and identify the types of intermolecular forces present in a substance. This course is for students who have a complete understanding of atomic theory and electronic configuration. It is a mandatory course for all students of chemistry, biochemistry, and materials science, and a direct prerequisite for the study of organic chemistry.

Payment required for enrolment

Enrolment valid for 12 months

This course is also part of the following learning track. You may join the track to gain comprehensive knowledge across related courses.

[NUC Core] CHM 101: General Chemistry I

This learning track delivers the complete NUC CCMAS curriculum for General Chemistry I. It is a comprehensive programme designed to build a robust, university-level foundation in modern chemistry. The track systematically covers all essential topics, from atomic theory, chemical bonding, and the states of matter, to the quantitative principles of stoichiometry, equilibrium, thermodynamics, and kinetics. This programme is for first-year undergraduates in science, technology, engineering, and mathematics (STEM) faculties who are required to take CHM 101. It is also essential for any student or professional globally who needs a rigorous and complete foundation in first-year university chemistry for further study or career development. This track delivers a full skill set in chemical theory and quantitative problem-solving. Graduates will be able to determine molecular structures, calculate reaction quantities, analyse the energetics and rates of reactions, and solve complex equilibrium problems. This programme provides the non-negotiable prerequisite knowledge for all subsequent chemistry courses and for any degree in the physical sciences, engineering, or medicine.

Course Chapters

1. Introduction

This chapter provides the roadmap for the course. It outlines the progression from the fundamental nature of chemical bonds to the theories that predict the three-dimensional shapes of molecules. Key learning objectives include: understanding the overall course structure and appreciating why the shape of a molecule is critical to its function.

Chapter lessons

1-1. Welcome

This lesson provides a brief overview of the course, outlining the key topics of chemical bonding, molecular geometry, and intermolecular forces.

2. Types of Bonds

This chapter covers the fundamental forces that hold atoms together in chemical compounds. It details the primary types of intramolecular bonds: ionic, covalent, and metallic. Key learning objectives include: defining ionic and covalent bonds based on electron transfer and sharing; and understanding the nature of metallic bonding.

Chapter lessons

2-1. Ionic bonding

This lesson defines an ionic bond as the electrostatic attraction between oppositely charged ions, formed by the transfer of electrons from a metal to a non-metal.

2-2. Covalent bonding

This lesson defines a covalent bond as the sharing of electron pairs between two non-metal atoms. The concepts of single, double, and triple bonds are introduced.

3. Lewis Structures

This chapter focuses on Lewis structures, the two-dimensional diagrams used to represent valence electrons and bonding in molecules. Mastering this is a critical skill for predicting molecular geometry. Key learning objectives include: applying the octet rule to draw correct Lewis structures for any simple molecule or polyatomic ion; and using the concept of formal charge to determine the most stable structure.

Chapter lessons

3-1. Drawing Lewis structures

This lesson provides a systematic, step-by-step procedure for drawing Lewis structures, including how to count valence electrons and satisfy the octet rule.

3-2. Resonance and exceptions

This lesson introduces the concept of resonance for molecules that cannot be represented by a single Lewis structure. Common exceptions to the octet rule are also covered.

3-3. Calculating formal charge

This lesson explains how to calculate the formal charge on each atom in a Lewis structure, a tool used to determine the most plausible structure among different possibilities.

4. Shapes of Molecules

This chapter introduces Valence Shell Electron Pair Repulsion (VSEPR) theory, the primary model for predicting the three-dimensional geometry of molecules. The focus is on applying the theory to determine electron and molecular shapes. Key learning objectives include: using VSEPR theory to determine the electron geometry around a central atom; and predicting the final molecular geometry and bond angles for any simple molecule.

Chapter lessons

4-1. VSEPR theory

This lesson introduces the core concept of VSEPR theory: electron pairs in the valence shell of a central atom repel each other and arrange themselves to be as far apart as possible.

4-2. Electron vs molecular geometry

This lesson explains the crucial distinction between the electron geometry (the arrangement of all electron pairs) and the molecular geometry (the arrangement of only the atoms).

5. Hybridization Theory

This chapter covers the concept of orbital hybridization, a model used to explain the observed shapes of molecules that VSEPR theory alone cannot. It connects bonding to the mixing of atomic orbitals. Key learning objectives include: defining orbital hybridization; and identifying the correct hybridization (sp, sp², sp³) for the central atom in a molecule.

Chapter lessons

5-1. Valence bond theory

This lesson introduces valence bond theory, which describes a covalent bond as the overlap of atomic orbitals.

5-2. Hybridization of orbitals

This lesson defines hybridization as the concept of mixing atomic orbitals to form new, hybrid orbitals with different shapes and energies, suitable for bonding.

5-3. Sigma and pi bonds

This lesson explains the two main types of covalent bonds based on orbital overlap: sigma (σ) bonds (end-to-end overlap) and pi (π) bonds (side-to-side overlap).

6. Intermolecular Forces

This chapter covers intermolecular forces, the attractive forces that exist between molecules. These forces are responsible for the physical properties of substances, such as melting and boiling points. Key learning objectives include: defining the different types of intermolecular forces; and predicting the relative strength of these forces to explain the physical properties of a substance.

Chapter lessons

6-1. Dispersion and dipole forces

This lesson covers the two main types of van der Waals forces: London dispersion forces, which exist in all molecules, and dipole-dipole forces, which exist only in polar molecules.

6-2. Hydrogen bonding

This lesson defines hydrogen bonding as an especially strong type of dipole-dipole interaction that occurs when hydrogen is bonded to a highly electronegative atom (N, O, or F).

7. Conclusion

This concluding chapter summarises the key concepts of chemical bonding and molecular geometry. It reinforces the connection between electronic structure, molecular shape, and the physical properties of matter. This summary prepares the student for the next course, 'Kinetic Theory of Matter and Gas Laws', where the interactions between molecules are explored further.

Chapter lessons

7-1. Course summary

This lesson consolidates knowledge by reviewing the progression from simple bonding theories to the prediction of 3D molecular shapes and the analysis of intermolecular forces.

7-2. Next steps

This final lesson looks ahead, explaining how a command of molecular shape and intermolecular forces is a direct prerequisite for understanding the bulk properties of matter, which is the focus of the next course.