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Sch2101:Chemical Bonding And Structure Question Paper
Sch2101:Chemical Bonding And Structure
Course:Bachelor Of Crop Protection
Institution: Meru University Of Science And Technology question papers
Exam Year:2014
QUESTION ONE – (30 MARKS)
(a) (i) Draw the molecular orbital diagram for H2 molecule. Label all the orbitals clearly. (4 Marks) (ii) Using a well labelled sketch diagram, illustrate the variation of the energy of hydrogen molecule ion ??2 + as a function of the internuclear separation for the electron in the ground state orbital and in the excited state orbital. (4 Marks)
(b) (i) Show the resonance structure for the nitrite ion, ? 2NO . (2 Marks)
(ii) Write the Lewis structure for the OCS molecule showing specifically how the octet rule is satisfied. C = 6, O = 8, S = 16 (2 Marks)
(c) (i) Assign formal charges to the following structures of the molecule, 2 SO : .. .. .... .. .. .. .. .. OSOandOSO ???? (6 Marks)
(ii) Which of the structures above is more plausible? Give an explanation for your answer. (4 Marks)
(d) Identify the favourable factors which are essential for the formation of an ionic bond. (4 Marks)
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(e) Use VSEPR model to describe the shapes of the following molecules; N = 7, H = 1 (i) 3 NH (ii) O H2 (4 Marks)
QUESTION TWO – (20 MARKS)
(a) (i) Using BOTH 3 3 NH andBF molecules, explain the concept of incomplete octet as used in chemical bonding. (5 Marks)
(ii) What type of a chemical bond would be formed between the molecules
33 NHandBF ? (2 Marks) (iii) From the reaction between 3 3 NH andBF , identify Lewis acid and Lewis base. (2 Marks) (b) Explain using suitable examples; (i) Bond order (ii) Polar bond (4 Marks)
(c) When 2 N molecule is bombarded with fast moving electrons, a molecular ion ? 2N is produced. (i) Write the electron configuration for the molecular ion, ? 2N . (2 Marks) (ii) Calculate the bond order of ? 2N (2 Marks) (iii) State and explain the magnetic property of the molecular ion ? 2N (2 Marks) (iv) Predict the bond length of ? 2N relative to the bond length of 2 N molecule. (1 Mark) QUESTION THREE – (20 MARKS)
(a) P, Q and R (not the actual symbols) are elements whose atomic number are 14, 17 and 20 respectively. Indicate the element that: (i) Forms a cation (ii) Form an anion (iii) Will form a compound with four hydrogen atoms. (6 Marks)
(b) What type of intermolecular interactions (forces) exist between the following pairs of molecules/ions: (i) S HandHBr 2
(ii) ? 22 NOandI
(iii) 6 63 H CandNH (8 Marks)
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(c) Study the data provided then answer the question that follow. Element Bond of Molecule Electronegativity of the element H H – H 2.20 Cl Cl – Cl 3.16
Use Pauli’s method to determine the electronegativity difference between H and Cl atoms in the molecule H – Cl. (3 Marks)
QUESTION FOUR – (20 MARKS)
(a) Using valence bond picture, draw labelled diagrams to show the formation of (i) Sigma bonding resulting from S and Px orbitals. (ii) Pi bonding in N2 molecule resulting from the Py - Py orbitals overlap. (4 Marks)
(b) (i) State rules governing the linear combination of molecular orbitals. (5 Marks)
(ii) Give molecular orbital energy level diagram, showing electron distribution for the C2 molecule. (3 Marks)’
(c) The atomic numbers for the elements, Cl, Kr and I are 17, 36 and 53 respectively. (i) Write the valence electronic configurations of Cl and I. (2 Marks) (ii) Show the Lewis structure for the polyatomic anion ? 4ICl (2 Marks) (iii) Draw molecular geometrical structure of the polyatomic anion ? 4ICl (3 Marks)
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