Structure of atom class 11 notes pdf

The model does not give any information about how electrons aredistributed around nucleus and what are energies of these electrons.

Is o t opes: These are the atoms of the same element having the same atomicnumber but different mass number. Electromagnetic radiations : The radiations which are associated withelectrical and magnetic fields are called electromagnetic radiations. When anelectrically charged particle moves under acceleration, alternating electricaland magnetic fields are produced and transmitted. These fields aretransmitted in the form of waves. These waves are called electromagneticwaves or electromagnetic radiations.

Oscillating electric and magnetic field are produced by oscillating charged particles. These fields are perpendicular to each other and both areperpendicular to the direction of propagation of the wave. They do not need a medium to travel.

That means they can even travel invacuum. Wavelength: It may be defined as the distance between two neighbouring crests or troughs of wave as shown. Velocity v : It is defined as the distance travelled by a wave in onesecond. In vacuum all types of electromagnetic radiations travel with thesame velocity. It is denoted by v d. Wave number: Wave number is defined as the number of wavelengths per unit length. Black body : An ideal body, which emits and absorbs all frequencies, is calleda black body.

The radiation emitted by such a body is called black body radiation. The phenomenon of ejection of electrons from thesurface of metal when light of suitable frequency strikes it is calledphotoelectric effect. The ejected electrons are called photoelectrons. Thisis called threshold frequency. Photoelectric work function Wo : The minimum energy required to ejectelectrons is called photoelectric work function. Energy of the ejected electrons :. The light possesses both particle and wave like properties, i.

Black body radiation and photoelectric effect Wave like properties are exhibited when it propagates interference an diffraction. When a white light is passed through a prism, it splits into a series ofcoloured bands known as spectrum. It has bright lines with dark spaces between them. Electromagnetic spectrum is a continuous spectrum.

It consists of a range ofelectromagnetic radiations arranged in the order of increasing wavelengths ordecreasing frequencies. It proves the following points:. Neutron must be a massive particle. There is a hollow space around it, from where particles get deflected. However, quite similar to the previous model, even Rutherford's atomic model was found to be defective in certain areas. It is known that any charged body revolving around a particle continuously radiate energy.

Plus, due to the presence of attractive forces, it is likely to fall into the core at one time and collide with the neutron. Through our Structure of Atom Class 11 Notes PDF, you will know that if this is true, then the electrons revolving around the neutron will ultimately collide into it.

However, this is not possible as it will defy the existence of things around us, thus proving the proposed theory to be incorrect.

Although an important concept, yet the atomic number and mass number are probably the most confusing terminologies in Physical Chemistry. Therefore, students need to be careful while dealing with both these.

Students will learn that —. The atomic number is the number of protons and represented by Z capital. The mass number is the total number of protons and neutrons and represented by A capital. Based on it, elements are categorised into the following:. Isoelectronic and. It is explained with the help of a few examples presented in a tabular form for more natural understanding.

The isotopes of hydrogen, oxygen and some other common elements are showcased here. Besides, isobars and other atomic properties are also presented in tables to simplify the representation of data and to apprehend the information. Tabular representation in our Structure of Atom Class 11 Notes PDF help in faster comprehending as well as quicker memorising of the same.

You can refer to these revision notes before your exam and recapitulate all that you have read across the year. After a detailed study of various atomic models, you will be introduced to energy forms in this section — electromagnetic radiation to be precise.

These are energy forms that are present all around us and can exist in various forms like —. Gamma rays and many more. You will be surprised to know that even the sun rays are electromagnetic radiations. We have made sure that you do not miss out on these important concepts in our Notes of Chemistry Class 11 Chapter 2 as it is the base for upcoming advanced study of atomic structure. Once this is clear, you can quickly get hold of the electronic configurations as well.

Electrons tend to change their existing positions due to this radiation when an atom absorbs energy. You need to be clear with the background for this topic that electromagnetic radiation, as the name suggests, is radiated from the electrically charged particles. You will find a diagrammatic representation of propagation of these waves in our Structure of Atom Class 11 Notes PDF which will guide you to have a better understanding of the same.

Here, you will know things like:. The nature of light can be both particle and wave, as suggested by field scientist Max Planck and Huygens, respectively. The relation between frequency and wavelength of light is shown with a mathematical formula. The Planck's constant, which is represented by l and its application and significance in these equations as well. Avogadro's number N will also find a place here, which is also presented in mathematical notation.

The wave nature of light is a standalone concept, and it has some related terminologies with it that have been listed in our Structure of Atom Class 11 Notes PDF. They are as follows:. All these terms have their respective sign conventions to represent them in formulas. Vedantu's Chemistry Class 11 Notes has all the signs presented carefully alongside each term to help you recall all the terms and signs easily.

Above all, students need to be thorough with formulas as it will help them in solving numerical problems included in this chapter. Class 11 Chemistry Chapter 2 - Electromagnetic Spectrum. Spectrum is the entire range of light radiations. Since most of the light present in this universe is invisible to the naked eye, starting from x-rays, radio waves to gamma rays. The part of visible light is those colours that make up a rainbow.

The spectrum is also labelled based on their wavelength to distinguish each of them. Due to this reason, our faculties have included a shortcut to remember the order so that you retain its sequence easily and score well in the exam. Further, you will find short notes on topics like:.

Electromagnetic theory. Failure of the approach due to two experiments namely,. Black body radiation. Photoelectric effect. Both these experiments are explained in brief with essential details to help you recall all the necessary information and terms to frame your answers in exams. Writing proper answers with relevant information will fetch you more marks than usual.

In our revision notes for Class 11 Chemistry Chapter 2, you will benefit because of the following reasons:. We have included appropriately labelled figures concerning theories to help you memorise them quickly. We have listed the observations in a pointwise manner to help you recapitulate the same before the exam.

We have drawn a comparison between the previous findings and these experiments. It is observed that new findings were completely contradicting the former. As a result, Max Planck's theory was proposed to overcome the limitations of previous experiments. Also, their easy and free download option makes it conveniently accessible for students irrespective of the time and place that they are in. Quantum is the term given to transfer of energy in the form of small packets called quantum.

Here, you will find another term used interchangeably with quantum in case of light — photon. To make it clear to students, we have also included two figures to showcase this phenomenon according to Planck's theory.

You will learn about:. Energy will be in whole number quanta. Explanation of black body radiation. Description of the photoelectric effect. Further, we have also cited two cases and their respective observations:. So students are advised to study our notes without any confusion.

Studying in class 12 has forever been a task for students as they have to deal with high pressure mainly in the field of tough chapter. Moreover, students not only require to appear for their final board examinations but also perform well and get good marks which are later used to plan future careers for them. Having said that, during class 12, Chemistry Chapter 2 Structure of Atom is an essential subject as well as a difficult one with many problems diagrams and many concepts.

Thus, studying all these will require some extra effort and students have to keep revising and practising to fully master the topic. While students may not have sufficient time to prepare notes by themselves, we at SelfStudys are giving well-organized NCERT Class 11 Chemistry Chapter 2 Structure of Atom Notes that will help them in their examination preparation and also expand more interest towards the concepts.

Students who practice these Chemistry Chapter 2 Structure of Atom notes will find that every concept is described in a lucid manner including the formulas, equations, diagrams and important questions. The difficulties of the Rutherford model were overcome by Niels Bohr in in his model of the hydrogen atom.

Bohr postulated that electron moves around the nucleus in circular orbits. Only certain orbits can exist and each orbit corresponds to a specific energy.

Bohr calculated the energy of electron in various orbits and for each orbit predicted the distance between the electron and nucleus. Bohr model, though offering a satisfactory model for explaining the spectra of the hydrogen atom, could not explain the spectra of multi-electron atoms.

The reason for this was soon discovered. In Bohr model, an electron is regarded as a charged particle moving in a well defined circular orbit about the nucleus. Dual behavior of matter: de Broglie proposed that matter exhibits dual behavior. This means matter shows both particle and wave nature. An orbit is a clearly defined path and this path can completely be defined only if both the exact position and the exact velocity of the electron at the same time are known.

Bohr model of the hydrogen atom, therefore, not only ignores the dual behaviour of electron but also contradicts Heisenberg uncertainty principle.