Class 10 Science Chapter 1: Chemical Reactions and Equations
Chapter 1 of the NCERT Class 10 Science textbook “Science”.
Chapter at a glance
A chemical reaction is a process in which substances change into new substances with different properties; atoms rearrange but are not lost. We recognise reactions by observable signs such as gas formation, colour change, temperature change, or formation of a solid (precipitate). Chemists write reactions as equations using chemical symbols and formulas; equations must show the same kinds and numbers of atoms on both sides. This part introduces these ideas, gives simple examples, and shows how to read and write basic symbol equations.
What you will learn: You will learn the meaning of a chemical reaction, common observable signs, how to write a word equation and a simple symbol equation, and how to check that atoms are conserved.
Why it matters: Understanding what changes during a reaction helps predict products, balance equations, and safely use reactions in daily life like cooking, cleaning and medicines.
Key concepts
- Chemical reaction — A process where starting substances change into new substances with different properties.
- Signs of a chemical reaction — Observable effects suggesting that a chemical change has taken place.
- Word and symbol equations — A way to write chemical reactions first in words, then with chemical formulas.
What the chapter covers
- Try at Home — A safe, supervised activity to see a chemical reaction and its sign.
- Why Questions — Short clear explanations to deepen understanding.
Remember for the exam
- Never change subscripts to balance.
- Always use smallest whole-number coefficients.
Common mistakes
- Mistake: Calling dissolving a substance always a chemical reaction. Better: Check whether new properties or new substances form (if not, it is physical).
- Mistake: Using (s), (l), (g), (aq) incorrectly or not at all. Better: Use (s) for solid, (l) for liquid, (g) for gas, (aq) for aqueous (dissolved in water).
- Mistake: Writing unbalanced equations and leaving them unchecked. Better: Always count atoms and show the final balanced equation with smallest whole-number coefficients.
These notes are a study aid. Check important facts against your textbook.
Study this chapter
- A clear study guide that explains the chapter step by step
- Quick revision for the day before a test
- Practice quizzes that show which ideas need more work
- An AI tutor to ask questions about “Chemical Reactions and Equations”
More in Class 10 Science
Chapter names follow the current NCERT textbooks. My Study Mantra does not reproduce textbook pages.