The following ball-and-stick molecular model is a representation of thalidomide, a drug that causes birth defects when taken by expectant mothers but is valuable for its use against leprosy. The lines indicate only the connections between atoms, not whether the bonds are single, double, or triple. (Red = O, gray = C, blue = N, ivory = H). Give the formula of thalidomide, and indicate the positions of multiple bonds and lone pairs.

Question

Ball-and-stick model of thalidomide, showing atom connections and colors: red=O, gray=C, blue=N, ivory=H.

Accepted Answer

welcome back everyone. The falling ball and stick model below shows caffeine, a stimulant found in coffee and tea. Shown below are the connections between the atoms provide the chemical formula for caffeine and fill in missing lone pairs. Were given a legend where we're told that the gray atoms are carbon. So we have carbon atoms. So eight gray tells us C. Sub eight for our formula. Then we have white equal to hydrogen. We would count 10 hydrogen atoms. So 10 white gives us a church sub 10 in the formula. Then we have according to the legend red for oxygen. We would count to read so two reds give us oh sub two. And then lastly we have blue atoms for nitrogen we see we have four blue atoms. And so that would be for blue corresponding to N sub four. Now riding out the chemical formula recall that they always begin with carbon atoms first, so C. Sub eight is first and then hydrogen following carbon. So we would have aged 10 next in the formula. And then after that all other elements are listed alphabetically. So we would list nitrogen first and sub four and then completing our formula last alphabetically we have oxygen as oh sub two. And so for our chemical formula we have C eight H 10 N 402 as our chemical formula of caffeine. And this would be our first answer where for our next answer we just need to fill in the lone pairs in our molecule for caffeine. And this is where we want to recall the concept of funding preference when it comes to bonding preference for carbon. Recall that it's stable when it has four bonds in a structure as far as hydrogen recall that because it only has one valence electron, it should only have a bonding preference of one bond When it comes to oxygen, recall that it's bonding preference to be stable is to have two bonds And two lone pairs. And the nitrogen we would recall has a bonding preference of three bonds And one lone pair. So this says two lone pairs here and so going to our molecule, let's focus on oxygen and nitrogen specifically. We can see that our red oxygen atoms do have two bonds, but they're missing their two lone pairs. So we'll draw those in as lone pair electrons, we have one set of two on this first oxygen and now we have our second set of two lone pairs on the second oxygen. And now looking to our blue nitrogen atoms, we see that they do have three bonds each, however, they're missing there single lone pair. So drawing that in, we have one lone pair here, another here, a third lone pair here and then 1/4 lone pair on our fourth nitrogen atom. And with these lone pairs filled in this would complete this example as our second final answer for this entire structure with its filled in missing lone pairs. I hope that everything I did was clear. If you have any questions, please leave them down below and I'll see everyone in the next practice video.

Verified Solution

Key Concepts

Molecular Formula

Bond Types

Lone Pairs