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Chemical Bonding: Lewis Dot Structure for H2O (3 of 6) |
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Watch the video of Dr. B. drawing the Lewis dot structure for H2O and answer the questions below. The H2O Lewis dot structure is seen fairly frequently. A common error it to put two oxygen atoms and one hydrogen making HO2. Make sure you have two hydrogens and one oxygen in H2O! Hint: look at the questions before watching the video. H2O Lewis Structure Video Video Transcript: Here, we're going to do a dot structure for water, H2O. Let's write that down: H2O. What we want to find out first is how many valence electrons does water have. I'm counting all the outer shell electrons. I'll need my periodic table. Let's see, Hydrogen's in group 1, so it has one valence electron, but since there's two Hydrogens I need to multiply that by 2. Way over here, Oxygen has 6 valence electrons. It's in group 6 or 16. It has 6 outer shell electrons. We add those there for a total of 6 plus 2 times 1: 8. So we have eight total valence electrons to satisfy the octets of all the H's and O's with. We put the least electronegative one at the center; however, we always put Hydrogen on the outside. I'm just going to draw it. (I'm going to move it over here, give us some room.) H, O, H. Assign two electrons to each bond. So we're going to bond it together with a covalent bond here. So I've used 4 of my 8, so I have 4 left. Then complete the octets on the outside atoms. Here, because Oxygen needs 8. Hydrogen needs two, but it already has two. So I've completed the octets and I've used up all my electrons here. So I think we're OK there. Let's go ahead and check and see if we have satisfied the outer shells, everything's full. Oxygen has 8, Hydrogen has 2, this Hydrogen also has 2. You don't need to draw that on a test or a quiz, but it is good to check. I've used 2, 4, 6, 8 electrons, that's all I had. Everything has an octet. We're OK. So we're done with water. |
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