The Particulate Nature of Matter - Chemistry (Senior Secondary)

This course provides a complete introduction to the building blocks of all substances. It formally defines atoms, molecules, and ions, and covers the core principles of Dalton's atomic theory. The course then details the modern model of the atom, including its constituent particles, and introduces the concepts of atomic number, mass number, isotopes, and relative atomic mass. A correct understanding of the particulate nature of matter is the absolute foundation of all chemistry. It explains why elements and compounds behave the way they do and provides the framework for understanding chemical bonding, reactions, and stoichiometry. This is the microscopic viewpoint that makes sense of the macroscopic world. By the end of this course, you will be able to define atoms, molecules, and ions, state the postulates of Dalton's atomic theory, describe the properties of protons, neutrons, and electrons, determine the atomic and mass number of any element, and explain the concept of isotopy. This course is designed for senior secondary students (SSS 1). It is the essential prerequisite for the study of the periodic table, chemical bonding, and the quantitative analysis of chemical reactions.

Enrolment valid for 12 months

Course Chapters

1. Introduction
2

This chapter begins the study of matter at the microscopic scale. It outlines the course's scope before establishing the formal definitions of chemistry's fundamental particles: atoms, molecules, and ions. This vocabulary is essential for all subsequent topics. Key topics: understanding the course structure; defining the atom, molecule, and ion; and distinguishing between these three fundamental particles.

Chapter lessons

1-1. Welcome

A direct statement of the course's purpose and structure. This lesson outlines the progression from Dalton's atomic theory to the modern understanding of atomic structure and isotopes.

1-2. Atoms, molecules, and ions

Formally defines the fundamental particles of matter. It clarifies the distinction between a neutral atom, a molecule formed from bonded atoms, and an ion with a net electric charge.

2. Atomic Theory
2
1

This chapter covers the foundational theories of the atom. It begins with the definitions of atoms, molecules, and ions, and then provides a complete treatment of Dalton's atomic theory, which established the basis of modern chemistry. Key topics include the distinction between atoms, molecules, and ions, the postulates of Dalton's theory, and the evidence that supports these fundamental ideas.

Chapter lessons

2-1. Dalton's atomic theory

Details the four main postulates of John Dalton's atomic theory. This includes the concepts that matter is made of atoms and that atoms combine in simple whole-number ratios.

2-2. Evidence for Dalton's theory

Explains how the laws of chemical combination (conservation of mass, definite proportions, multiple proportions) provide the experimental evidence for Dalton's atomic theory.

3. Atomic Structure
2
2

This chapter details the modern model of the atom. It covers the three subatomic particles—protons, neutrons, and electrons—and their properties, establishing the nuclear model of the atom. Key topics include the properties and locations of protons, neutrons, and electrons, the definitions of atomic number and mass number, and how these are used to describe specific atoms.

Chapter lessons

3-1. Constituents of the atom

Introduces the three fundamental subatomic particles. It covers the relative mass, charge, and location of protons, neutrons, and electrons within the atom.

3-2. Atomic and mass numbers

Defines the atomic number (Z) as the number of protons and the mass number (A) as the total number of protons and neutrons. These numbers uniquely identify an atom.

4. Isotopes and Atomic Mass
2
4

This chapter introduces the concept of isotopes and explains how their existence affects the calculation of atomic mass. This is a critical concept for understanding the non-integer atomic masses found on the periodic table. Key topics include the definition of isotopes, their standard notation, and the calculation of relative atomic mass based on the weighted average of isotopic masses.

Chapter lessons

4-1. What is an isotope?

Formally defines isotopes as atoms of the same element that have the same number of protons but different numbers of neutrons. The standard notation for isotopes is also covered.

4-2. Relative atomic mass

Defines relative atomic mass as the weighted average mass of an element's isotopes. It explains why this value is often not a whole number.

5. Conclusion
2

This chapter consolidates the core concepts of the particulate nature of matter. It provides a structured summary of atomic theory, atomic structure, and isotopes, reinforcing the foundation for understanding chemical behaviour. The conclusion summarises the key definitions and models. It also provides a forward look to the next course on the periodic table, where these concepts will be used to explain elemental properties.

Chapter lessons

5-1. Course summary

A concise review of atoms, molecules, ions, atomic structure, and isotopes. This lesson ensures all the foundational principles of matter's particulate nature are consolidated.

5-2. Next steps: Periodicity

Explains how the understanding of atomic structure is the direct prerequisite for studying the periodic table and the trends in chemical properties.