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Chapter 13

Successive IEs

Clicker Question The following chemical reaction is exothermic: A2 + B2  2AB. This means: more stable higher average bond energies a) Reactants Reactants b) Reactants Products c) Products Products d) Products Reactants e) I do not know.

Chapter 13

H2(g) + Cl2(g)  2HCl(g) Determine ΔHf° for HCl(g): Use Appendix 4 Predict using bond energies

Lewis Structures Determine the total number of valence electrons in the molecule. Form at least one bond between atoms in the molecule (a pair of electrons is a bond) Arrange the rest of the electrons (in pairs) to satisfy the octet rule or duet rule (for hydrogen). Watch for exceptions.

Clicker Question Which of the following is the best Lewis structure for the hydrogen thiocyanate molecule (HSCN) taking formal charge into account? Note: the lone pairs are not included in these skeletal structures. Before answering the question, complete the Lewis structures. a) H-S-C≡N b) H-S=C=N c) H-S≡C-N d) H-S-C-N e) At least two of the above structures are equally valid when considering formal charge.