VR Tour For Std. 9 Ch. 3. Atoms and Molecules
What's Included in Virtual tour of this chapter
Atoms are the basic building blocks of matter whereas molecules contain one or more atoms. Atoms are the smallest unit that contains a chemical element. We will learn in this chapter about the law of conservation and the law of constant/definite proportions. Further in the chapter, we will discover the atomicity of the molecule. It is classified as monatomic, diatomic, triatomic, tetra-atomic, or polyatomic.

Virtual tour 1: Law of conservation of mass
The Law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. In other words, we will learn that the mass of any one element at the beginning of a reaction will equal the mass of that element at the end of the reaction.

Virtual tour 2: Law of constant proportions
This law was stated by Proust as “In a chemical substance the elements are always present in definite proportions by mass”. The Law of constant composition states that a given chemical compound always contains its component elements in a fixed ratio (by mass) and does not depend on its source and method of preparation.

Virtual tour 3: Information about atom
Compounds are made by the combination of 2 or more kinds of; the atoms in a compound are chemically bonded and hence cannot be separated at the easy ratio of the atomic mass of atoms in any substance like water is the same in all situations.

Virtual tour 4: Molecules of elements
A molecule is made of a combination of atoms. Each element has a specific number of atoms that combine together and form a molecule. We will also learn about the atomicity of the molecule. They are monoatomic, diatomic, triatomic, tetra-atomic, or polyatomic.