Atomic Structure Level 3

ATOMIC STRUCTURE Passage : Orbital is the region in an atom where the probability of finding the electron is maximum. It represents three-dimensonal motion of an electron around the nucleus. Orbitals do not specify a defi nite path according to the uncertainty principle. An orbital is described with the help of wave function  . Whenever an electron is described by a wave function, we say that an electron occupies that orbital. Since many wave functions are possible for an electron, there are many atomic orbitals in an atom. Orb ital s have different sha pes; except s-orbitals, all other orbitals have directional character. Number of spherical nodes in an orbital is equal to (n––1). Orbital angular momentum of an electron is Q.1 Q.2 Q.3 The nodes present in 5p orbital are (A) one planar, five spherical (B) one planar, four spherical (C) one planar, three spherical (D) four spherical When an atom is placed in a magnetic field, the possible number of orientations for an orbital of azimuthal quantum number 3 is (A) three (B) one (C) five (D) seven Orbital angular momentum of f-electrons is(A) Q.4 (  1)  . 2 (B) 3 (C) 12  (D) 2 Which of the following orbitals has/have two nodal planes ? (A) dxy (B) dyz (C) dxz (D) All of these True or False: Q.5 The species Na+, Mg2+, Al3+, O2– and F– are iso-electronic. Q.6 9 Be  42 He126 C 01n 4 The nuclear reaction was used by curie to discover neutron. Q.7 Lyman series of hydrogen spectrum lies in the visible region. Q.8 All the four quantum number have been derived from Schrodinger wave equation. Q.9 The outer electronic configuration of chromium atom is 3d44s2. Q.10 The electron density in xy plane of 3d x 2 – y 2 orbital is zero. Q.11 All the atomic orbitals are directional in nature. 1 Q.12 The designation of an orbital, n = 4 and  = 0 is 4s. Q.13 Chromium atom has six unpaired electrons. Q.14 The energies of various subshells in the same shell are in the order of s > p > d > f. Each of the questions given below consist of Statement – I and Statement – II. Use the following Key to choose the appropriate answer. (A) If both Statement- I and Statement- II are true, and Statement - II is the correct explanation of Statement– I. (B) If both Statement - I 8 and Statement II are true but Statement - II is not the correct explanation of Statement – I. (C) If Statement - I is true but Statement II is false. (D) If Statement - I is false but Statement II is true. Q.15 Statement I : 2p orbitals do not have any spherical node. Statement II : The number of nodes in p-orbitals is given by (n – 2) where n is the principal quantum number. Q.16 Statement I : All p-orbitals have only one planar node. Statement II : The number of radial nodes depends on the principal quantum number only. Q.17 Statement I : A spectral line will be seen for a 2px – 2py transition. Statement II : Energy is released in the form of waves of light when the electron drops from 2px to 2py orbital. Q.18 Statement I : Hydrogen has one electron in its orbit but it produces several spectral lines. Statement II : There are many excited energy levels available. Q.19 Statement I : The 19th electron in potassium atom enters into 4 s-orbital and not the 3d-orbital. Statement II : (n + ) rule is followed for determining the orbital of the lowest energy state. Q.20 Statement I : The free gaseous Cr atom has six unpaired electrons. Statement II : Half-filled s-orbital has greater stability. Q.21 Statement I : The electronic configuration of the nitrogen atom is represented as ATOMIC STRUCTURE Statement II : The electronic configuration of the ground state of an atom is the one which has the greatest multiplicity. Q.22 Statement I : For n = 3,  = 0, 1 and 2 and m may be 0; 0, ± 1 and 0, ± 1 and ± 2. Statement II : For each value of n, there are 0 to (n – 1) possible values of  and for each value of , there are 0 to ±  values of m. Q.23 Statement I : The radial probability distribution curves of 2s, 3p, 4d and 5f orbitals are identical in shape. Statement II : The number of planar nodes present in these orbitals is different. Q.24 Statement I : 2px, 2py and 2pz each have one nodal plane. Statement II : These orbital are degenrate orbitals. Column Matching: Q.25 Column-I (A) 2s (B) 1s (C) 2p (D) 3p Column-II (P) Angular node = 1 (Q) Radial node = 0 (R) Radial node = 1 (S) Angular node = 0 Q.26 Column-I (A) n = 6  n = 3 (B) n = 7  n = 3 (C) n = 5  n = 2 (D)n = 6  n = 2 Column-II (P) 10 lines in the spectrum (Q) Spectral lines in visible region (R) 6 lines in the spectrum (S) Spectral lines in infrared region LEVEL # 3 1. C 2. D 3. C 4. D 5. True 6. False 7. False 8. False 9. False 10. False 11. False 12. True 13. True 14. False 15. A 16. C 17. D 18. A 19. A 20. C 21. A 22. A 23. B 24. B 25. A  P,R; B  Q,S; C  Q,P; D  P,R 26. A  R,S; B  P,S; C  R,Q; D  P,Q