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FAQs on NCERT Books for Class 12 Physics Chapter 12 - Atoms Free PDF Download
1. How are atoms formed?
The old-age theory about the origin of an atom was that atoms are formed when all the planets in our universe collide with each other. This is called 'Big Bang Theory. But now, two theories are proposed to explain the formation of atoms..1) 'Plasma Theory'.2) 'Continuous Spontaneous Generation theory
Plasma Theory: According to this theory, at the beginning of the universe, all matter existed as plasma. A plasma is a gas in which some of its atoms are ionized to produce electrical currents.
Continuous Spontaneous Generation theory: According to this theory, there is no end to the universe, and everything is in a continuous process. One part of the plasma becomes dense and collapses, which forms a star system with all planets orbiting around it. This collapse may form the sun or the stars etc. In such stars, atoms are formed when a helium nucleus collides with a hydrogen atom.
2. What are the types of Atoms?
There are two types of atoms. One is the natural atom, and another one is an artificial atom that can be artificially produced by us. Artificial atoms are also called 'artificial molecules'.We can define artificial atoms or artificial molecule in terms of how it reacts with other things like-
It reacts with only some specific type of elements
It cannot react with anything else apart from a small range of elements
It reacts with a large number of elements. For example, in H2, the element 'hydrogen' is an artificial atom as it can only react with other atoms, which are also hydrogen. On the other hand, SO4 is not an artificial atom as it reacts with many types of elements.
3. What is the significance of an atom? What role does it perform?
An atom performs four roles in its life-
It helps in changing the chemical environment of other atoms.
The electrons inside it help in transferring energy from one atom to another atom.
The protons and neutrons inside it provide a place for other atoms to attach to.
Protons and neutrons provide a nucleus for maintaining the shape of the atom.
Hence, we see that all atoms in our body are interacting with each other, and hence they can never remain as isolated entities. Hence, it is always better to say 'Atoms interact'. Vedantu provides free physics tuition for students after class 12th. Register at vedantu.com to get free online tuitions, study material, and NCERT solutions of Class 6 to 12 Physics.
4. How are atoms separated?
When you dissolve something in the water, what actually happens is that particles of atoms break down into small enough parts so that they merge with the water molecules. The atoms are so small that they cannot be seen with the naked eye. When you mix two or more types of solute, then it is very difficult to separate the resulting mixture into its original parts as they have now formed new molecules which can only be separated by breaking covalent bonds, ionic bonds etc.
5. How big is an atom?
An atom has a very small size, yet it contains many things within itself, such as protons, neutrons, electrons, and an atomic nucleus. Atoms are not seen by the human eyes and cannot also be touched. A microscope is mostly used to observe them. An atom contains protons, electrons and neutrons. Protons are positively charged particles with a mass nearly 2 000 times greater than the mass of electrons. Neutrons are neutral particles with a mass nearly 2000 times greater than electrons. An atom contains 99.95% space, i.e., only 0.05% content consists of protons, electrons and neutrons that can be observed by instruments like microscopes etc.
