Class 9th Chemistry Chapter 2 Notes

Important Notes on Class 9th Chemistry Chapter 2 Notes Urdu Medium written by Honorable Sir M. Shahid Suib. These notes are very helpful in the preparation of Atomic Structure Class 9 Notes for students of the Class 9th Chemistry Chapter 2 Notes Urdu Medium and these are according to the paper patterns of all Punjab boards.

Summary and Contents:
Topics which are discussed in the notes are given below:
  • Here are the detailed chemistry class 9th chapter 2 notes to help you prepare for your exams.
  • Complete Exercise MCQs of Chapter No.2 Structure of Atom in Urdu Medium
  • Complete Exercise Short Questions with Answers of Chapter No.2 Structure of Atom in Urdu Medium
  • Introduction: Ancient Greek philosopher Democritus suggested that matter is composed of tiny indivisible particles called atoms. The name atom was derived from the Latin word 'Atomos' meaning indivisible. In the beginning of 19th century John Dalton put forward Atomic Theory. According to it 'all matter is made up of very small indivisible particles called atoms'. Till the end of 19th century it was considered that atom cannot be subdivided. However, in the beginning of 20 century experiments performed by Goldstein, J. J. Thomson, Rutherford, Bohr and other scientist revealed that atom is made up of subatomic particles like electron, proton and neutron. Properties of these subatomic particles will be discussed.
  • THEORIES AND EXPERIMENTS RELATED TO STRUCTURE OF: ATOM: According to Dalton, an atom is an indivisible, hard, dense sphere. Atoms of the same element are alike. They combine in different ways to form compounds. In the light of Dalton's atomic theory, scientists performed a series of experiments. But in the late 1800's and early 1900's, scientists discovered new subatomic particles.
  • In 1886, Goldstein discovered positively charged particles called protons. In 1897, J.J. Thomson found in an atom, the negatively charged particles known as electrons. It was established that electrons and protons are fundamental particles of matter. Based upon these observations Thomson put forth his "plum pudding" theory. He postulated that atoms were solid structures of positively charge with tiny negative particles stuck inside. It is like plums in the pudding.
  • Cathode rays and Discovery of Electron: In 1895 Sir William Crooks performed experiments by passing electric current through gases in a discharge tube at very low pressure.
  • Download the 9th class chemistry chapter 2 notes today and start your exam preparation without any hassle.
  • He took a glass tube fitted with two metallic electrode, which were connected to a high voltage battery. The pressure inside the tube was kept 10 atm. When high voltage current was passed through the gas, shiny rays were emitted from the cathode which travel towards the anode. These rays were given the name of "cathode rays" as these were originated from the cathode.
  • ELECTRONIC CONFIGURATION: Before discussing electronic configuration let us first understand the concept of shells and subshells. We have learnt about the structure of atom i.e. it consists of a tiny nucleus lying in the center and electrons revolving around the nucleus. Now we will discuss how the electrons revolve around the nucleus? The electrons revolve around the nucleus in different energy levels or shells according to their respective energies (potential energy). The concept of potential energy of an electron shall be discussed in higher classes.
  • Energy levels are represented by 'n' values 1, 2, 3 and so on. They are designated by the alphabets K, L, M and so on. A shell closer to the nucleus is of minimum energy. Since K shell is closest to the nucleus, the energy of shells increases from K shell onwards.
  • Important MCQs and Questions: Which one the following shell consist of three subshells:
  • Which radioisotope is used for the diagnosis of tumor in the body?
  • When U-235 breaks up, it produces:
  • The p subshell has:
  • Deuterium is used to make:
  • The isotope C-12 is present in abundance of:
  • Who discovered the proton?
  • How many isotopes of oxygen exist?
  • If n = 4 than how many electrons can be accommodated in its shells?
  • p subshell can accommodate electrons?
  • Number of neutrons of potassium is:
  • Who is the Father of Nuclear Sciences?
  • “N” shell can accommodate electrons:
  • Electronic configuration of Nitrogen is:
  • “M” shell can accommodate maximum number of electrons:
  • Charge on neutron is:
  • Who discovered the electron?
  • “L” shell can accommodate electrons:
  • Almost all the particles passed through the foil undeflected. This observation was made by:
  • M shell consists of no of subshells.
  • State two characteristics of cathodes.
  • State two properties of neutrons.
  • State two characteristics of positive res.
  • For what purpose is uranium used?
  • Define nuclear fission reaction.
  • Write the observations of Rutherford atomic model.
  • What are the facts of Rutherford's atomic model?
  • How many electrons are there in s,p,d and f subshell?

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