Title Class 09 Science 4 Structure of the Atom.pdf ✅

Structure of the Atom DPP-01 [Topic: Charged Particles in Matter, The Structure of an Atom] Very Short Answer Type Questions 1. Name three subatomic particles present in an atom. 2. Name the negatively charged particles present in all the atoms of all the elements. 3. Which part of the atom was discovered by Rutherford's alpha particle scattering experiment? 4. What are Canal rays? 5. If an atom contains one electron and one proton, will it carry any charge or not? 6. Why is an atom neutral inspite of the presence of charged particles in it? 7. How does a proton differ from an electron? 8. Helium atom has atomic mass of 4uu and has 2 protons in its nucleus. How many neutrons does it have? 9. Who discovered electrons? 10. What is a proton? Who discovered it? 11. What was the main drawback of Rutherford's model of atom? 12. Name an element which does not have any neutron. Short Answer Type Questions-I 13. Mention any two points which Rutherford put forward to explain the nuclear model of an atom. 14. Compare the properties of electrons, protons and neutrons. 15. What are the limitations of J.J. Thomson's model of the atom? 16. What are the limitations of Rutherford's model of atom? Short Answer Type Questions-II 17. Describe Thomson's model of atom. Which subatomic particle was not present in Thomson's model of Atom? 18. Describe Rutherford's model of atom. 19. Describe Bohr's model of atom. Long Answer Type Question 20. Compare all the proposed models of an atom given in this chapter.
Structure of the Atom DPP-02 [Topic: Distribution of Electrons in Shells, Valency, Atomic Number, Mass Number, Isotopes and Isobars] Very Short Answer Type Questions 1. The total number of electrons in Nitrogen is 7. What is its valency? 2. What name is given to the pair of atoms: 7 14N and 7 15N ? 3. Oxygen has 8 protons and 8 neutrons whereas sulphur has 16 protons and 16 neutrons. What is the mass number of oxygen and sulphur. 4. The atomic number of neon is 10. Write its electronic configuration. 5. What happens to the element ' ZZ ' if it can gain three electrons? 6. Helium has 2 electrons in its valence shell but its valency is not 2. Explain 7. According to Bohr Bury Scheme what is the maximum number of electrons present in M-shell of an atom? 8. In the notation 7 14N, what do the numbers 14 and 7 denote? 9. If Mg2+ has 12 protons and 12 neutrons, what is its atomic number and mass number? 10. What is the difference between Na atom and Na+ion in terms of number of electrons? 11. Why are the shells in which electrons revolve are called energy levels? 12. Why is Co − 60 used in the treatment of cancer? 13. Which isotope is used to find the age of a mummy? 14. Which isotope is used as a fuel in Nuclear reactors? 15. What is the formula of the compound when ' X ' with atomic number 12 combines with an element with atomic number 17? 16. An ion of an element has 3 units positive charge. Mass number of the atom is 27 and the number of the neutrons is 14. What is the number of electrons in this ion? 17. In a sample of ethanoate (CH3COOC2H5), the oxygen atoms have the same number of electrons but different number of neutrons. What is a relationship between two atoms of oxygen? 18. Elements with valency equal to one are (a) always metals (b) always metalloids (c) either metals or non-metals (d) always non-metals 19. Which of the following statement is always correct? (a) An atom has equal number of electrons and protons.
(b) An atom has equal number of electrons and neutrons. (c) An atom has equal number of protons and neutrons. (d) An atom has equal number of electrons, protons and neutrons. 20. Will 35Cl and 37Cl have different valencies? Justify your answer. 21. Why did Rutherford select a gold foil for his αα-ray scattering experiment? 22. One electron is present in the outermost shell of the atom of an element X. What would be the nature and value of charge on the ion formed, if this electron is removed from the outermost shell? 23. In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, what would be the charge on the ion so formed? Short Answer Type Questions-I 24. For the symbol H,D and T tabulate three sub-atomic particles found in each of them. 25. Write the electronic configuration of any one pair of isotopes and isobars. 26. Summarise the rules for writing of distribution of electrons in various shells for the first eighteen elements. 27. Define valency by taking the examples of silicon and oxygen. 28. Na+ion has completely filled K and L shells. Explain. 29. If bromine atom is available in the form of, say, two isotopes 35 79Br(49.7%) and 35 81Br(50.3%). Calculate the average atomic mass of bromine (Br) atom. 30. The average atomic mass of a sample of an element X is 16.2u. What is the percentage of isotopes 8 16X and 8 18X in the given sample? 31. If ZZ = 3, what would be the valency of the element? Also, name that element. 32. Composition of the nuclei of two atomic species X and Y are given as under Nuclei X Y Protons 6 6 Neutrons 6 8 Give the mass numbers of X and Y. What is the relation between the two species? 33. The following data represents the distribution of electrons, protons and neutrons in atoms of the elements: A, B, C, D: