Secondary 1 Chemistry | Free Notes
Chemistry in Secondary 1 is all about understanding the stuff around us – what things are made of, how they behave, and why they change. Think of it as learning the rules behind everyday things like cooking, rusting, melting ice, or even why air takes up space.
Last updated 17 January 2026
Introduction to Chemistry: What Is Chemistry?
Chemistry is the study of matter and how it changes. Matter is anything that has mass and occupies space. This includes solids like tables, liquids like water, and gases like air (yes, air is matter too!).
In Sec 1, you won’t jump straight into complicated formulas. Instead, you’ll focus on understanding matter at a basic level and learning how scientists observe and measure it accurately.
Chapter 1: States of Change
All matter exists in three main states:
Solid: Has a fixed shape and fixed volume. Particles are packed closely together and vibrate in place (e.g. ice, metal).
Liquid: Has a fixed volume but no fixed shape. Particles are close together but can move past one another (e.g. water, oil).
Gas: Has no fixed shape and no fixed volume. Particles are far apart and move freely (e.g. air, oxygen).
Changes between these states are called physical changes because no new substance is formed.
Chapter 2: Physical vs Chemical Changes
A key idea in Sec 1 Chemistry is telling the difference between these two:
Physical change: No new substance is formed. Usually reversible.
Examples: melting ice, boiling water, dissolving sugar in water
Chemical change: A new substance is formed. Usually irreversible.
Examples: burning paper, rusting of iron, cooking an egg
A simple test: if you can’t easily get the original substance back, it’s likely a chemical change.
Chapter 3: Elements, Compounds and Mixtures
Everything around us can be classified into one of these:
Element: A pure substance made of only one type of atom (e.g. oxygen, iron).
Compound: A pure substance made of two or more elements chemically combined in a fixed ratio (e.g. water, carbon dioxide).
Mixture: Two or more substances mixed together physically, not chemically (e.g. air, saltwater).
Mixtures can be separated using physical methods, while compounds cannot.
Chapter 4: Separation of Mixtures
Since mixtures are not chemically combined, we can separate them using simple techniques such as:
Filtration – separating an insoluble solid from a liquid
Evaporation – removing a solvent to obtain a dissolved solid
Distillation – separating liquids with different boiling points
These methods are commonly tested and often appear in practical questions.
Chapter 5: Measurement in Chemistry
Chemistry relies on accurate measurements. Common quantities you’ll learn include:
Mass (measured in grams, g)
Volume (measured in cm³ or dm³)
Temperature (measured in °C)
Always pay attention to units – losing marks over units is one of the most common mistakes students make.
Still need help with Secondary 1 Chemistry?If chemistry feels confusing or hard to follow, you’re not alone. At UpLabs Learning Centre, we explain concepts step by step so students can understand clearly — not just memorise. Our tutors are patient, supportive, and experienced with the school syllabus. We help students build confidence early and keep up in class. 👉 Try a lesson with UpLabs and make chemistry easier to understand. |
Comments