Chapter 8, Problem 62
For Group 13–17 elements in the third row of the periodic table and beyond, the octet rule is often not obeyed. A friend of yours says this is because these heavier elements are more likely to make double or triple bonds. Another friend of yours says that this is because the heavier elements are larger and can make bonds to more than four atoms at a time. Which friend is more correct?
Video transcript
Mothballs are composed of naphthalene, C10H8, a molecule that consists of two six-membered rings of carbon fused along an edge, as shown in this incomplete Lewis structure:
(b) Do you expect the C—C bond lengths in the molecule to be similar to those of C—C single bonds, C ═ C double bonds, or intermediate between C—C single and C ═ C double bonds?
Mothballs are composed of naphthalene, C10H8, a molecule that consists of two six-membered rings of carbon fused along an edge, as shown in this incomplete Lewis structure:
(c) Not all of the C—C bond lengths in naphthalene are equivalent. Based on your resonance structures, how many C—C bonds in the molecule do you expect to be shorter than the others?
(b) Which of these compounds or ions is an exception to the octet rule: borohydride (BH4-), borazine (B3N3H6, which is analogous to benzene with alternating B and N in the ring), or boron trichloride?
Draw the Lewis structures for each of the following molecules or ions. Identify instances where the octet rule is not obeyed; state which atom in each compound does not follow the octet rule; and state how many electrons surround these atoms: (a) PF6-, (b) BeCl2, (c) NH3, (d) XeF2O (the Xe is the central atom), (e) SO42- .
In the vapor phase, BeCl2 exists as a discrete molecule. (a) Draw the Lewis structure of this molecule, using only single bonds. Does this Lewis structure satisfy the octet rule?
In the vapor phase, BeCl2 exists as a discrete molecule. (c) On the basis of the formal charges, which Lewis structure is expected to be dominant for BeCl2?