← 🧪 Chemistry · usually met in Std 7-12
Atoms rearranging into new combinations. Nothing is lost and nothing is created — which is the whole reason an equation has to balance.
In a chemical reaction the bonds between atoms break and new ones form, producing substances with new properties. Rust is iron, oxygen and water becoming iron oxide. Burning is a fuel combining with oxygen, releasing heat and light. Digestion is a long controlled sequence of reactions. The atoms themselves are untouched: the same ones that went in come out, grouped differently.
Because of that, every atom on the left of an equation must appear on the right, which is what balancing means. Reactions that release energy are exothermic, like burning; reactions that absorb it are endothermic, like the cold pack that goes cold when you squeeze it. Temperature, surface area, concentration and a catalyst all change how fast a reaction goes, without changing what it produces.
Want to see it moving? Search YouTube for “Chemical reactions” ↗ — we send you to the search rather than to one video, because a link to one video eventually rots.
This entry was written for Star Student in our own words — it is a summary, not a source. Here is where the people who actually hold these facts keep them. Go and check.
Your own textbook ↗Balbharati publishes the textbooks free to read online. Your chapter is the thing to check first — an encyclopedia is a summary, and the syllabus is the syllabus.Last gone through: 1 October 2026 · How these entries are written
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