3A Brief Review of Three Shortcuts in Drawing Dot Structures- Spring 2006 - Sparks

3A Brief Review of Three Shortcuts in Drawing Dot Structures- Spring 2006 - Sparks

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A Brief Review of Three Shortcuts in Drawing Dot Structures 1. Often, the lone pairs are left off. For example: Could be drawn simply as H-O-H Since you know that O wants 8 electrons, you would know that there should be two lone pairs on the oxygen. Hence, if there are no lone pairs shown, you should think about how many electrons each atom wants (almost always 8, except in the exceptions like H and the ones discussed on page 5 of the course packet) and add the lone pairs as needed. 2. C almost always has 4 bonds and no lone pairs. C is very often bonded to H. Therefore, a shortcut that saves much time is to leave H atoms off when (and only when) they are bonded to a C atom. Hence:
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Unformatted text preview: C C C C C H H H H H H H H H H becomes C C C C C Since you know C always (essentially) has 4 bonds and you know that any element other than H must be explicitly shown, you can determine the number of H atoms bound to each C. The leftmost H already has two bonds, so it must also have two H atoms bound to it. The second-to-left H already has three bonds, so it must have one H bound to it. And so on. 3. Since there are a huge number of C-containing compounds, we can save even more time by not having to write the C for carbon every time it appears in a structure. Hence: C C C C C becomes where each end of a line and each intersection are understood to be a C atom. H O H...
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