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(d) Cathode rays produce X-rays when they strike a metal target of a high atomic number such as tungsten, which is highly penetrating. The radius of a nucleus: $\quad R = R _{0}( A )^{1 / 3}$ cm, 3. The arrangement of various types of electromagnetic radiations in the order of their increasing or decreasing wavelengths or frequencies is known as the electromagnetic spectrum. Formulas of State of Matter. The Notes on the Structure of an atom of Class 11 has been divided into two articles. Formulas of Electrochemistry. (d) Wavenumber is the number of wavelength per centimeter. Rutherford conducted a series of experiments using α-particles. Radius of orbit. However, if H2 gas is used in discharges, the positive rays particles are named as protons (usually represented as P). Formulas of Chemical Kinetics and Nuclear Chemistry. Estimation of closest distance of approach (derivation) of $\alpha$-particle : $\quad R =\frac{4 KZe ^{2}}{ m _{\alpha} V _{\alpha}^{2}}$, 2. 6. (b) Some of the α-particles were deﬂected from their original paths through moderate angles, indicating that the whole of the positive charge is concentrated in a space called nucleus. A major point of this model is that the mass of atom is considered to be spread uniformly over the atom. The charge on the electron was calculated to be – 1.6022 × 10-19 C. An electron has the smallest charge known; so it was, designated as a unit negative charge. The specific charge (e/m) of canal rays particles varied with the nature of gas and was found to be maximum if H2 was used. It is obtained from the substances which emit light on excitation, that is, either by heating the substances on a film or by passing electric discharge through a thin filament of high melting point metal. Wavelength of emitted photon: 1 λ =¯v=RZ2( 1 n2 1 − 1 n2 2) 1 λ = v ¯ = R Z 2 ( 1 n 1 2 − 1 n 2 2) 8. ū = 1/λ = v/c = (1/n 1 2 – 1/n 2 2) where, R is universal constant, known as Rydberg constant. (b) These consist of electric and magnetic fields that oscillate in directions perpendicular to each other and perpendicular to the direction in which the wave is travelling. Download Chemistry Notes PDF for class 11 FREE only at BYJU'S. The positive rays particles were thus, called positively charged gaseous atoms left after the removal of an electron or ionized gaseous atoms. The value of e/m has been found to be – 1.7588 × 108 C/g. Here is the list of all the Important Formulas of Structure of Atom Class 11. The spectrum of hydrogen is an example of the line emission spectrum or atomic emission spectrum. Also, all important experiments are explained in detail with illustrations wherever necessary. In 1909, the first precise measurement of the charge on an electron was made by Robert A. Millikan using his oil drop experiment. When a ray of this light is passed through a prism, a line spectrum is produced. n2 is greater than n1 by at least 1. This is known as the rest mass of the electron; that is, the mass of the electron when it is moving with low speed. (a) Most of the α-particles went straight without suffering any deﬂection. Formulas of Solid States. All electromagnetic waves travel with the same velocity, that is, 3 × 1010 cm/sec. The volume of the atom is about 1015 times the volume of the nucleus. 9. of neutrons. However when the pressure was reduced to 10–2 mm at a potential of 1000 volt, Crookes and Plucker noticed that: (i) From the cathode surface, a glow surrounding the cathode began and the space left between the glow and cathode was named Crookes dark space. The number of positive charge on the nucleus is different for different atoms. ū = 1/λ = v/c = (1/n12 – 1/n22) where, R is universal constant, known as Rydberg constant. Here is the detailed list of all the formulas of this chapter. Ch 2 Chemistry Class 11 - Relation Between Various Models and Bohr's Theory. (a) Every element is composed of extremely small indestructible particles called atoms (‘atom’ in Greek means indivisible). Thus, he pointed out that light has a wave as well as particle characteristics (dual nature). Following conclusions were drawn from these observations: (a) Many of the particles went straight through the metal foil undeﬂected, indicating that there must be very large empty space within the atom. Following are the important characteristics of EMR: (a) All electromagnetic radiations or waves travel with the velocity of light. \Delta p>\frac{h}{4 \pi}$or$m \Delta x \cdot \Delta v \geq \frac{ h }{4 \pi}$or$\Delta x . At “Study Material Center” you will get all the important exam related study material, such as Notes, Study Material, Formula bank, Previous Year Chapterwise Questions etc. Under this condition, electric current starts to ﬂow from one electrode to another. The e/m of a neutron is zero. Its value is 0.9678 cm -1 , n 1 and n 2 are integers (such that n 2 > n 1 ). It is the reciprocal of wavelength and is denoted by the symbol ν (nu bar). The emission of electrons from a metal surface, when exposed to light radiations of appropriate wavelength, is called the photoelectric effect. The Notes on the Structure of an atom of Class 11 has been divided into two articles. Mass of the electron: The mass of the electron is calculated from the values of e/m. Download the free Pdf of chapter-Atomic Structure formula for class 11 chemistry . 146C,  157N, 168O, are called isotones. (b) Cathode rays produce ﬂuorescence when they fall on certain substances like ZnS. In 1905, Einstein pointed out that light can be considered to consist of a stream of particles, called photons. This type of spectrum that contains a lesser number of wavelengths in the emergent light than in incident light is called an absorption spectrum. 4. In 1897 J. J. Thomson determined the charge/mass value of the electron by studying the deﬂection of cathode rays in electric and magnetic fields. 4018Ar, 4019K, 4020Ca are known as isobars. The wavelengths of the different lines show that these lines are in the visible, ultraviolet and infrared regions. 3. The emitted electrons are called photoelectrons. The energy associated with each quantum of given radiation is proportional to the frequency of the emitted radiation. CBSE Class 12 Chemistry - Important Formulas all chapters. Dalton’s atomic theory (1808) is based on the following two laws: the law of conservation of mass and law of definite proportions. Heisenberg's uncertainty principle Atomic number of an element = Total number of protons present in the nucleus, = Total number of electrons present in the neutral atom This article is on the Structure Of An Atom Class 11 Notes of Chemistry.The notes on the structure of an atom of class 11 chemistry have been prepared with great care for the students so that they can give a quick glance of the chapter. According to Einstein, energy is also related as E = mc2 where m is the mass of a photon. Chapter-wise CBSE Class 11 Chemistry Notes: Chapter 1 - Some Basic Concepts of Chemistry; Chapter 2 - Structure of Atom Your email address will not be published. (f) Time period is the time taken by one wave to complete a cycle or vibration and is denoted by T. T = 1/ν. Wavelength of emitted photon: $\frac{1}{\lambda}=\bar{v}=R Z^{2}\left(\frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}}\right)$, 8. Answer: (i) Mass of an electron = 9.1 × 10 -28 g. (a) An atom consists of a positively charged heavy nucleus where all the protons and neutrons are present. Note: An electron can thus be defined as a subatomic particle which carries charge -1.60 ×10-19 C, that is, one unit negative charge and has mass 9.1 × 10-19 g, that is, 1/1837 the mass of the hydrogen atom (0.000549 amu). Such atoms of different elements having different atomic numbers, but have the same mass number, e.g. Save my name, email, and website in this browser for the next time I comment. The second article (Part 2) includes Bohr’s model, Heisenberg’s Uncertainty principle, Quantum mechanical model, Quantum numbers, Pauli’s principle, Aufbau principle and Hund’s Rule. Emr: ( i ) mass of an atom is first Chapter in Chemistry Class 11 Neutron ) oil. Lab Manual Chemistry Sample Papers save my name important formulas of chemistry class 11 chapter 2 email, and so is! Edubuzzer, welcome to the cube root of the α-particles went straight without suffering any.! 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