Atomic Theory and Atomic structure. Part A. d) Distance of electrons from the nucleus

Transcription

1 Grade Subject Topic : AP : Science : Atomic Theory and Atomic Structure Atomic Theory and Atomic structure Part A (1) The Principal quantum number represents a) Shape of an orbital b) Number of electrons in an orbit. c) Number of orbits d) Distance of electrons from the nucleus (2) The shape of an orbital is governed by a) Magnetic quantum number b) Spin quantum number c) Principal quantum number d) Azimuthal quantum number Page 1 of 6

2 (3) A line spectrum is a) Characteristic of an element b) Used to identify a compound. c) Given by a compound d) All the above (4) Magnetic quantum number specifies a) Shape of the orbital b) Orientation of orbitals in space c) Number of orbits d) Number of electrons in an orbit. (5) The atomic number of an atom X is 7.The X 3- ion will have a) 7protons and 10electrons b) 10protons and 7electrons c) 4protons and 7 electrons d) 7protons and 4 electrons Page 2 of 6

3 (6) Which of the statements is a contradiction to Dalton s atomic theory. a) Atom can neither be created nor destroyed. b) Number of atoms changes when a substance changes its physical state. c) Number of atoms does not change when a substance changes its physical state. d) The total number of atoms during a chemical reaction remains unaltered. (7) The order of filling of electrons in the orbital of an atom will be a) 3d, 4s, 4p, 4d, 5s. b) 5s, 4p, 3d, 4d, 5s c) 4s, 3d, 4p, 5s, 4d d) 3d, 4p, 4s, 4d, 5s (8) The compound in which the cation is isoelectronic with the anion is a) NaCl b) K2S c) KCl d) KI (9) The electronic configuration of x, y and z and m is as given below. Which one is most metallic? a) x=2,8,8,1 b) y=2,8,1 c) z=2,8,7 d) 2,8,8 Page 3 of 6

4 (10) Within the same period, an increase in atomic number is accompanied by a) Decrease in atomic radius and increase in electro negativity. b) A decrease in atomic radius and a decrease in electro negativity. c) An increase in atomic radius and an increase in electro negativity. d) All are incorrect. (11) In which of the following sets of elements are the atomic radius nearly the same a) Be, B, C, N b) Ne, Ar, Kr, Xe c) Mg, Ca, Sr, Ba d) Cr, Mn, Fe, Co Use the answers given below for answering questions 12 to 14 a) O b) La c) Rb d) Mg e) N (12) Which element is most electronegative? Page 4 of 6

5 (13) Which element will exhibit the greatest number of different oxidation states? (14) Which of the elements above has the smallest ionic radius (15) According to Bohrs model of an atom a) Angular momentum of electron is quantized b) Total energy of electron is quantized. c) Spin momentum of electron is quantized d) All the above are correct. Part B (1) The atomic numbers of elements X, Y and Z are 12,19 and 24 respectively. Locate the period and group of these elements. (2) Which of the ions given below are isoelectronic with Argon (a) Ag +, Br -, Cd 2+, Fe 3+, I -, S 2-, Sc 3+, Zn 2+, Ca 2+ Page 5 of 6

6 (3) The atomic number of Fe is 26.Write the electronic configuration of Fe2+ and Fe3+. Which one has more unpaired electrons? (4) The melting point and atomic radii of three elements x, y and z is given in the table below. Each of the elements has n electrons in its valence shell. Element x y z Melting point At. 0 radii (pm) a) Does element x, y and z belong to the same group, give reasons to support your answer. b) Which element will be most metallic and least metallic? c) Arrange them in the order of increasing atomic numbers (5) Calculate the number of electrons, protons and neutrons in the following. (a) NH 4 + (b) H 3 PO 4 (c) PO 4 3- At. No of N=7, H=1, O=8, P=15 Page 6 of 6