Class 9 Science - ODISHA
Atomic Foundations of Matter
The chapter 'Atomic Foundations of Matter' in Class 9 Science for Odisha BSE students introduces the fundamental building blocks of everything around us: atoms and molecules. You will learn the historical development of atomic theory, starting from Maharishi Kanad and Democritus to John Dalton's modern atomic theory. The chapter covers crucial laws of chemical combination, such as the Law of Conservation of Mass and the Law of Constant Proportions. It also explains how to calculate atomic mass, molecular mass, and formula units, which form the bedrock of numerical problems in chemistry for your board exams.
Start Learning FreeKey Concepts
Law of Conservation of Mass
Mass can neither be created nor destroyed in a chemical reaction; the total mass of reactants equals the total mass of products.
Law of Constant Proportions
In a chemical substance, the elements are always present in fixed proportions by mass, regardless of the source of the compound.
Dalton's Atomic Theory
States that all matter is made of tiny, indivisible particles called atoms, which have unique properties for each element.
Atom and Molecule
An atom is the smallest particle of an element that takes part in chemical reactions, while a molecule is a group of two or more atoms chemically bonded together.
Chemical Formula
A symbolic representation of the composition of a compound, determined by balancing the valencies of the combining atoms or ions.
Important Formulas
Board Exam Info
This chapter carries around 6 to 8 marks in the Odisha BSE Class 9 annual examinations. Common question types include numerical problems on molecular mass calculation, defining laws of chemical combination, and writing chemical formulas of simple compounds.
Frequently Asked Questions
What is the difference between an atom and a molecule?
An atom is the basic unit of an element that may or may not exist independently, whereas a molecule is formed when two or more atoms combine and can exist independently.
How do we find the molecular mass of a compound?
You add up the atomic masses of all the individual atoms present in one molecule of that compound, measured in atomic mass units (u).
Who first proposed the idea of atoms in ancient India?
The ancient Indian philosopher Maharishi Kanad postulated the existence of indivisible particles of matter, which he called 'Parmanu'.
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