Draw Lewis dot structures for each hypothetical molecule shown below, using the correct number of valence electrons for each atom. Determine which molecule makes sense because each atom has a complete valence shell, and each bond has the correct number of electrons. Explain what makes the other molecule nonsensical, considering the number of bonds each type of atom can make.

Question

Draw Lewis dot structures for each hypothetical molecule shown below, using the correct number of valence electrons for each atom. Determine which molecule makes sense because each atom has a complete valence shell, and each bond has the correct number of electrons. Explain what makes the other molecule nonsensical, considering the number of bonds each type of atom can make.

Accepted Answer

Hello all next, we'll look at this question. Which of the following represents the correct lewis dot structure of the following molecule. So we're given a skeletal structure showing the bonds in a compound that has hydrogen, carbon and oxygen. And we want to evaluate which lewis dot structure is correct. Those are the structures here that represents the outer shell electrons as dots. So we can see where the electrons come from in the different bonds. So let's just remind ourselves with each of these atoms how many valence electrons they have? Carbon has four valence electrons in its outer shell. It's going to want to share electrons and bonds until it has a full outer shell of eight electrons. Then we've also got oxygen and oxygen has six valence electrons. So it will want to share electrons and bonds to get two more and have a full shell of eight. And finally hydrogen just as one valence electron. But because it's a small atom with just its outer shell is just in the first energy level, it only takes two electrons in that s orbital to fill it up. So now let's look down at our structures and see which one is correct. So starting with choice A Let's look one at a time at each of the atoms and see if they have the correct number of valence electrons represented. So in a let's start with carbon first carbon here, four electrons, second four but the third carbon here has an extra fifth valence electron. So a cannot be the correct answer. Now let's just scroll up a little to show choice B. Let's look at our carbons first carbon four valence electrons. Second carbon four third carbon 42 of them being shared in the double bond here with oxygen. So let's move on to oxygen. Well here we run into our problem. This oxygen atom is shown having four pairs or eight valence electrons in blue here. So it has two extra electrons. So be cannot be the correct lewis dot structure. So now let's move on to choice. See carbon 14 electrons, carbon to four valence electrons. Carbon 34 valence electrons. Now let's look at oxygen correctly shown with six valence electrons. And now let's look at the hydrogen right away on the left hand side. This first hydrogen is shown as having two valence electrons. So we've got an extra electron on hydrogen. So choice C cannot be correct either. Well, now we've just got one left. So we will guess that that will be our correct answer. But let's just double check that everything looks correct. Our carbons each with four atoms, four electrons are oxygen with six valence electrons, each of our hydrogen with a single electron. And now we'll just double check that each is shown having a full outer shell due to the bonds where it's sharing electrons. So here these hydrogen are all in single bonds, thereby sharing an electron and getting to in their outer shells. These first carbon four single bonds to allow it to fill its shell with eight. The second carbon, also four single bonds. Now this last carbon Has a double bond with oxygen, so they're sharing four electrons between them with the two electrons in single bonds. That gives this carbon it's eight full shell. Let's look at this oxygen. Oxygen has a double bond with carbon, giving it those two extra electrons to fill its outer shell. So everybody's happy with a full outer shell and everybody's got the right number of valence electrons. So that makes choice D are correct answer, showing the correct lewis dot structure of this molecule. See you in the next video.

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Key Concepts

Lewis Dot Structures

Valence Electrons

Bonding Capacity