A Tutorial on Atomic Structure: Notes, Figures and Problems with Solutions
Target Audience: These notes on Atomic Structure are meant for college freshmen, or high school students in Grades 11 or 12.
They might be of use to Indian students preparing for the ISC or CBSE Class 11 and 12 Examinations, IIT JEE (main and advanced), AIEEE; students from across the world preparing for their A Level Examinations, IB (International Baccalaureate) or AP Chemistry.
This compilation of notes has been prepared by Ayushi Patel of IIT Gandhinagar.
Complete Tutorial with Problems, Figures and Solutions :
Summary and Outline of Notes: Here's a quick recap of the outline of topics which were covered in this tutorial
Electron: They are carrier of negative charge and were discovered by cathode ray experiment.
Proton: They carry positive charge and has same magnitude of charge as that of electron.One proton has a mass of about 1.6726 × 10-27kg
It has no charge.It has a mass equal to that of proton.
CATHODE RAY DISCHARGE TUBE EXPERIMENT AND CONCLUSIONS:
This experiment was conducted by Michael Faraday.Cathode ray tube is made up of glass with anodes and cathodes on its’ two sides.The electrodes were made up of metals and inside the tube
gas was filled but the tube was still kept partially empty.The electrodes were connected to a battery with high voltage and also when the pressure was low,the gas started glowing.
Thomsons’ watermelon model
Thomson also proposed a model of atom similar to a watermelon in which he considered that positive and negative charges are equal in magnitude.This model verifies neutrality of atom but if positive and negative charges are distributed in such a way then they will attract each other and the structure won't be stable .
Rutherford’s atomic model:
In this experiment Rutherford passed rays of alpha particles from an alpha emitter through a gold foil and then it was observed that most of the rays passed straight way,very few returned back and some deviated after striking the gold foil by small angles.
Bohr’s atomic model:
Bohr also developed a model for hydrogen atom in which he said that electrons in an atom lie in energy states which are stationary and called as orbits.He also concluded that when an electron goes from high to low energy state it emits energy and while going from low to high energy state it absorbs energy and electron moves in circular orbit around the nucleus in such a way that its angular momentum is an integral multiple of h/2π
Photoelectric effect : There is immediate ejection of electrons from the surface of metal when light beam of certain frequency strikes on it.This is known as the photoelectric effect.
Heisenberg’s uncertainty principle: This principle states that it is impossible to decide both simultaneously and accurately position and momentum of a microscopic moving particle.
Quantum numbers : They are used to specify the orbitals and the electrons. We will also discuss the principal quantum number, azimuthal quantum number, spin and magnetic quantum number.
Pauli’s Exclusion principle: It is not possible for an atom to have all 4 quantum numbers same for two electrons.
Hunds’ rule of maximum multiplicity: The pairing of orbitals of the atom is started only when each orbital has occupied one electron.
Schrodinger Wave Equation:The Schrodinger wave equation is used to find the probability of presence of electron.This place where probability of finding electron is highest is known as orbital.