Careers360 Logo
Atoms

Atoms

Edited By Team Careers360 | Updated on May 06, 2022 10:48 AM IST

Introduction:
Every element is made up of tiny, invisible particles known as atoms. Every atom is a sphere in which the total mass is equally distributed and the nucleus is surrounded by negatively charged electrons. According to Dalton's Atomic Theory, all elements are made up of very small, invisible particles known as atoms. Atoms of the same element are identical, but atoms of different elements differ. According to Thomson's Atomic Model, the total mass is uniformly distributed and negatively charged electrons are randomly inserted. The atom is completely neutral. Rutherford made the following observations based on this experiment. The nucleus is a relatively small area that contains the whole positive charge and virtually all of the mass of the atom. Negatively charged electrons circle the nucleus in a variety of orbits. The entire negative charge on an electron equals the total positive charge on the nucleus. As a result, the atom as a whole is neutral. The electrostatic force of attraction between the electrons and the nucleus provides the centripetal force required by the electron for rotation. Louis-Broglie proposed the daring theory that matter must have a dual nature as well. He realised the duality theory for matter after making the following observations: Matter and electromagnetic radiation make up the entirety of the universe's energy. Nature is drawn to symmetry. Because radiation has a dual nature, the matter must have a dual nature as well. Every moving particle, according to the hypothesis, Broglie's has a wave associated with it. De-Broglie waves, often known as matter waves, are such waves.

List of topics according to NCERT and JEE Main/NEET syllabus:

  • Dalton's Atomic Theory.
  • Thomson's Atomic Model.
  • Limitations of Thomson's Atomic Model.
  • Impact Parameter.
  • Rutherford's Scattering Formula.
  • Limitations of Rutherford Atomic Model.
  • Bohr’s Atomic Model
  • Hydrogen Spectrum Series
  • Wave Model

Related Topics,

Important concepts and Laws:

Bohr’s Atomic Model

The angular momentum of an electron can be an integer multiple of (h / 2π) for certain non-radiating orbits called stationary orbits.

mvr = nh / 2π

where n = I, 2, 3,... is referred to as the principal quantum number.

Only when an electron jumps from one permissible orbit to another permitted orbit can energy radiation occur.

Energy of emitted photon

hv = E2 – E1

E1 and E2.are the energy of electrons in orbits, respectively.

The radius of an electron's orbit is determined by

r = n2h2 / 4π2 mK Ze2 ⇒ r ∝ n2 / Z

n = principle quantum number

h = Planck’s constant

m = mass of an electron

K = 1 / 4 π ε

Z = atomic number

e = electronic charge.

The electron's velocity in any orbit is determined by

v = 2πKZe2 / nh ⇒ v ∝ Z / n

The frequency of an electron in any orbit is calculated as follows:

v = KZe2 / nhr = 4π2Z2e4mK2 / n3 h3

The kinetic energy of an electron in any orbit is calculated as follows:

Ek = 2π2me4Z2K2 / n2 h2 = 13.6 Z2 / n2 electron Volt

Potential energy of electron in any orbit is given by

Ep = – 4π2me4Z2K2 / n2 h2 = 27.2 Z2 / n2 electron Volt

⇒ Ep = ∝ Z2 / n2

The total energy of an electron in any orbit is calculated as follows:

E = – 2π2me4Z2K2 / n2 h2 = – 13.6 Z2 / n2 electron Volt

⇒ Ep = ∝ Z2 / n2

Each element produces a specific spectrum of radiation that is unique to that element. The line spectrum is a series of separate parallel lines that make up the spectrum.

The Lyman Collection When an electron jumps from orbit n = 2, 3, 4,... to orbit n = 1, a Lyman series is formed. This series belongs to the ultraviolet spectrum.

The Balmer Collection is a collection of works by Balmer When an electron jumps from a n = 3, 4, 5,... orbit to a n = 2 orbit, a Balmer series line is formed. This series is set in the visual realm.

Paschen Collection When an electron jumps from orbit n = 4, 5, 6,... to orbit n = 3, a line of Paschen series is formed. This series belongs to the infrared spectrum.

Series Brackett When an electron jumps from the n = 5,6, 7,... orbit to the n = 4 orbit, a Brackett series line is formed. This series belongs to the infrared spectrum.

Series Pfund When an electron jumps from orbit n = 6,7,8,... to orbit n = 5, a Pfund series is formed. This series belongs to the infrared spectrum.

NCERT Notes Subject wise link:

Importance of Atoms for class 12

Unit-8, Atoms, and Nuclei are covered in Chapter 12 of Class 12 Physics. According to the new CBSE curriculum, the total weightage of Unit-7 (Dual Nature of Radiation & Matter) and Unit-8 in the board exam is 12 marks. In admission examinations like JEE and NEET, Unit 8 is heavily weighted. It carries a weightage of 3% in NEET, and 1 or 2 questions from this unit are expected to appear in the JEE Main Exam. Full marks on your board examinations are feasible if you study and comprehend the ideas thoroughly. It is not difficult to achieve full marks in any chapter if you work hard. In terms of grades, the situation with Physics Chapter 12 is no different. Physics, as a scientific topic, is all about facts and figures, and in order to get this knowledge straight on your test paper, you'll need to have all of your ideas crystal clear, as well as a firm foundation that will give you the confidence to attempt and solve all of the problems properly.


NCERT Solutions Subject wise link:

NCERT Exemplar Solutions Subject wise link:

Frequently Asked Questions (FAQs)

1. According to Chapter 12 Atoms of Class 12 Physics, what is the Plum Pudding model?

Thomson's Model is also known as Plum Pudding Model. From the beginning of Chapter 12 of Class 12 Physics, you will study about the many atomic model theories. The Thompson Model is one of them. The atom is said to be like a plum or a watermelon in this concept. There is a reddish orangish fleshy portion with seeds embedded in it, similar to watermelon or plum. Thompson believed that the positive charge of the atom is represented by the fleshy section, while the negatively charged electrons are represented by the seeds.

2. What limitations does Thomson's atomic model have?

It was unable to explain the origin of hydrogen and other atoms' spectrum series, as well as large angle scattering of – particles.

3. What are the drawbacks of Rutherford's atomic model?

During its orbital motion, an electron should generate energy in the form of an electromagnetic wave, according to Maxwell's electromagnetic wave theory. As a result, the radius of the electron's orbit would steadily decrease, eventually falling inside the nucleus, and the Rutherford atomic model will be unable to describe the atomic line spectrum.

4. What Does Bohr's Radius Mean?

The radius of the initial orbit of the hydrogen atom is defined as Bohr's radius. It has a value of 5.29 x 10-11m ~  0.53 Å.

5. According to Chapter 12 Atoms in Class 12 Physics, what are the numerous atomic models?

"Atoms" is the title of Chapter 12 of Physics in CBSE Class 12. The many atomic model theories developed by various physicists are explored in this chapter. Thomson's Model of Atom, Rutherford Atomic Model, and Bohr's Model of Atom, commonly known as Bohr's Theory, developed by Neil Bohr, are some of the model hypotheses explored.

Articles

Questions related to

Question : Read the passage and answer the following questions.
All great thinkers live and move on a high plane of thought. It is only there they can breathe freely. it is only in contact with spirits like themselves they can live harmoniously and attain that serenity which comes from ideal companionship. The studies of all great thinkers must range along the highest altitudes of human thoughts' have always thought that the strongest argument in favor of the Baconian theory was, that no man, however indubitable his genius, could have written the plays and sonnets that have come down to us under Shakespeare's own name who had not the liberal education of Bacon. The magnificent ideals that have ever haunted of though the human mind and given us our highest proofs of future immortality by reason of the impossibility of their fulfillment here are splintered into atoms by contact with life's realities. Hence Comes our sublime discontent's habitual mediation on the vast problems that underline human life and are knit into human destinies-thoughts of immortality, of the littleness to the mere man, of the greatness of man' soul, of the splendors of the universe that are invisible to the ordinary traffickers in the street, as the vastness of St. Peter's is to the spider that weaves her web in a corner of the dome-these things do not fir men to understand the arrange humanity is easy to understand, therefore, Why such thinkers fly to the solitude of their own thoughts, or he the silent companionship of the immortals and if they care to present their verse to the world that these views take a somber and melancholy setting from "the pale cast of thought" in which they were engendered.

Question:

What is referred as Baconian liberal education?
 

Option 1: An imaginary and ideal fantasy.


 

Option 2: Theory of acing human beings rue over their fate.

Option 3: Involvement with the complexities of the day to day life.


 

Option 4: Equivalent to ancient ideas of sublimity

Correct Answer: Involvement with the complexities of the day to day life.


 


Solution : The correct option is 3.

Baconian liberal education is the involvement with the complexities of the day to day life.

Explanation:

It is stated that "The magnificent ideals that have ever haunted of though the human mind and given us our highest proofs of future immortality by reason of the impossibility of their fulfillment here are splintered into atoms by contact with life's realities."
- Baconian liberal education is clearly linked to everyday life.

Correct Answer: Avogadro made a distinction between atoms and molecules.


Solution : The correct option is Avogadro made a distinction between atoms and molecules.

Avogadro distinguished molecules from atoms for the first time in 1811. He also proposed Avogadro's Law: equal amounts of gas at the same pressure and temperature have the same number of molecules.

Question : Read the passage and answer the following questions.
All great thinkers live and move on a high plane of thought. It is only there they can breathe freely. it is only in contact with spirits like themselves they can live harmoniously and attain that serenity which comes from ideal companionship. The studies of all great thinkers must range along the highest altitudes of human thoughts' have always thought that the strongest argument in favor of the Baconian theory was, that no man, however indubitable his genius, could have written the plays and sonnets that have come down to us under Shakespeare's own name who had not the liberal education of Bacon. The magnificent ideals that have ever haunted of though the human mind and given us our highest proofs of future immortality by reason of the impossibility of their fulfillment here are splintered into atoms by contact with life's realities. Hence Comes our sublime discontent's habitual mediation on the vast problems that underline human life and are knit into human destinies-thoughts of immortality, of the littleness to the mere man, of the greatness of man' soul, of the splendors of the universe that are invisible to the ordinary traffickers in the street, as the vastness of St. Peter's is to the spider that weaves her web in a corner of the dome-these things do not fir men to understand the arrange humanity is easy to understand, therefore, Why such thinkers fly to the solitude of their own thoughts, or he the silent companionship of the immortals and if they care to present their verse to the world that these views take a somber and melancholy setting from "the pale cast of thought" in which they were engendered.

Question:

Why do great thinkers love the idea of solitude?

Option 1: To be in pursuit of the ideal in the company of immortals
 

Option 2: To be calm and have peace of mind.


 

Option 3: Because they are introvert
 

Option 4: Because they are unable to deal with the complexities of life 

Correct Answer: To be in pursuit of the ideal in the company of immortals
 


Solution : The correct option is 1

Explanation:

As stated in the passage,  "Why such thinkers fly to the solitude of their own thoughts, or he the silent companionship of the immortals and if they care to present their verse to the world that these views take a sombre and melancholy setting from "the pale cast of thought" in which they were engendered."
- Therefore, great thinkers enjoy spending time alone with their thoughts in order to pursue the ideal in the company of immortals.

Correct Answer: Isotopes


Solution : The correct answer is Isotopes.

Isotopes are those atoms which have the same number of protons but different numbers of neutrons.

For example- There are three isotopes of Hydrogen. They are Protium, Deuterium, and Tritium. Where Protium only has one electron and one proton, Deuterium has one electron, one proton, and one neutron, while Tritium has one electron, one proton, and two neutrons.

Question : Read the passage and answer the following questions.
All great thinkers live and move on a high plane of thought. It is only there they can breathe freely. it is only in contact with spirits like themselves they can live harmoniously and attain that serenity which comes from ideal companionship. The studies of all great thinkers must range along the highest altitudes of human thoughts' have always thought that the strongest argument in favor of the Baconian theory was, that no man, however indubitable his genius, could have written the plays and sonnets that have come down to us under Shakespeare's own name who had not the liberal education of Bacon. The magnificent ideals that have ever haunted of though the human mind and given us our highest proofs of future immortality by reason of the impossibility of their fulfillment here are splintered into atoms by contact with life's realities. Hence Comes our sublime discontent's habitual mediation on the vast problems that underline human life and are knit into human destinies-thoughts of immortality, of the littleness to the mere man, of the greatness of man' soul, of the splendors of the universe that are invisible to the ordinary traffickers in the street, as the vastness of St. Peter's is to the spider that weaves her web in a corner of the dome-these things do not fir men to understand the arrange humanity is easy to understand, therefore, Why such thinkers fly to the solitude of their own thoughts, or he the silent companionship of the immortals and if they care to present their verse to the world that these views take a somber and melancholy setting from "the pale cast of thought" in which they were engendered.

Question:
According to the passage,  we can say that great thinkers are content to live______

 

Option 1: In the middle of crisis of civilizations
 

Option 2: In their thoughts, with an exceptional calm. 

Option 3:
At secluded mountains away from society.

Option 4: With the complexities and madness of life. 

 

Correct Answer: In their thoughts, with an exceptional calm. 


Solution : The appropriate response is 2. 

In their thoughts, with an exceptional calm. 

Explanation

"Why such thinkers fly to the solitude of their own thoughts, or he the silent companionship of the immortals and if they care to present their verse to the world that these views take a somber and melancholy setting from "the pale cast of thought" in which they were engendered." is mentioned.
- Therefore, great thinkers are happy to keep their ideas to themselves because if they share them with others, it will be obvious where their ideas came from—weak displays of thought.

Are previous year questions repeated in JEE Mains?
How to crack JEE Main in 1st attempt?
When will JEE Main admit card come?
How to check JEE Main Exam Centre?
How to check JEE Main Result?
How to make jee main admit card correction?
How to download jee main admit card?
How to download JEE Main admit card without password?
What not to carry to JEE Main exam hall?
What to carry to the exam hall of JEE Main 2018?
Back to top