Answer to Question #338654 in General Chemistry for Austine

Question

7.       Urea, a compound formed in the liver, is one of the ways humans excrete nitrogen.  

          The Lewis structure for urea is

Using hybrid orbitals for carbon, nitrogen, and oxygen, determine which orbitals overlap

to form the various bonds in urea

Answer 1

You'll notice that it is a fairly small molecule containing two nitrogen atoms, one carbon, one oxygen and four hydrogen atoms For a total of 24 valence electrons. Giving us a lewis structure that has two lone pairs on oxygen and one lone pair on each of the nitrogen. To determine hybridization, You'll notice that there are four electron groups surrounding the nitrogen. Three of them are bonding groups. One of them is a non bonding group. four electron groups always corresponds to an sp³ hybridization. So both of these are sp³ hybridized Carbon and oxygen. Both contain three electron groups. There are three bonding groups to single and one double around carbon. There is one bonding group, the double bond and two lone pairs surrounding oxygen. As its three electron groups, three electron groups always corresponds to sp² hybridized. So we have two sigma bonds here, there so two sp³ hybridized orbital's that overlap to produce the sigma bond. And then up here we have a signal bond created from an sp² on carbon and an sp² on oxygen overlapping. Because each of these are sp² hybridized, Both the carbon and the oxygen have an unhappy brid ized P orbital. These p orbital's can overlap to form the pi bond and then down here, although not requested in the problem, there's no hybridization on carbon. It's just it's atomic s orbital overlapping with the sp³ hybridized or below and nitrogen. So we have two sigma sp³ S bonds the same over here