F10HW11-CH9 - HOMEWORK WEEK 11 CHAPTER 9 9.9 As the H atoms...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
HOMEWORK WEEK 11 CHAPTER 9 9.9 As the H atoms approach one another, their 1 s orbitals begin to overlap. Each electron can then occupy the space around both atoms; that is, the two electrons are shared by the atoms. We can also use Lewis dots to represent the sharing of electrons by two atoms. Each atom behaves as though it “owns” the electrons in the bond. 9.10 Cl + Cl Cl 2 240 kJ/mol Bond dissociation energy Bond length 194 pm Distance between the nuclei Potential Energy Forming the bond is given by the process: Cl + Cl → Cl 2 . The energy or enthalpy change is given by: ΔH for bonding = H(products) – H(reagents) = H(Cl 2 ) – H(Cl + Cl) The diagram shows that Cl 2 has a lower energy (enthalpy) than Cl + Cl. Thus the ΔH is a negative quantity, which means, as usual, that the process is exothermic. 9.14 The absolute difference in the electronegativities of the two atoms in a bond is directly related to the polarity of the bond. Thus as the electronegativity difference increases, the electrons in the bond are shifted more strongly to the more electronegative atom, which means that the bond is more polar. 9.16 Molecules having an odd number of electrons do not obey the octet rule. An example is nitric oxide, NO. The other exceptions fall into two groups. In one group are molecules with an atom having fewer than eight valence electrons around it. An example is borane, BH 3 . In the other group are molecules with a central atom having more than eight valence electrons around it. The central atom must lie beyond the 2 nd period of the periodic table. An example is sulfur hexafluoride, SF 6 . [This last group is most important for us]. 9.19 (a) The bonding in the CO 3 2- ion is covalent, while the Ba 2+ and CO 3 2- ions show ionic bonding. The electronegativities of C and O do not differ greatly, explaining why the bonding in CO 3 2- is (polar) covalent. For (b) and (c), the bonding is mainly ionic (use electronegativities or note the metals present) For (d) and (e), the bonding is mainly (polar) covalent. ** Note that the CO 3 2- ion in BaCO 3 and the SO 4 2- ion are similar: both are ions, but contain covalent C-O and S-O bonds.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
9.29 a. Incorrect. The atoms in this formula do not obey the octet rule. The formula has the correct number of valence electrons, so this suggests that a multiple bond between the N atoms is needed. b. Correct. The central atom is surrounded by more electronegative atoms as you would expect, each atom obeys the octet rule and the correct number of electrons has been used. c. Incorrect. The skeleton structure is acceptable (the central atom is surrounded by more electronegative atoms), but you would expect the double bond to be between C and O rather than C and F (C, N, O, and S form multiple bonds). You would come to this same conclusion using rules of formal charge. The formula shown has a formal charge of +1 on F and -1 on O whereas, if you switch the double bond to be between C and O, neither O nor F has a non-zero formal charge. A formal charge of +1 on F is very unfavorable.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 8

F10HW11-CH9 - HOMEWORK WEEK 11 CHAPTER 9 9.9 As the H atoms...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online