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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: maccha on October 18, 2009, 02:59:44 PM

Title: Lewis diagrams and perspective drawings
Post by: maccha on October 18, 2009, 02:59:44 PM

Hi, I have a question about lewis diagrams for molecules with the parent shape trigonal bipyramidal. My textbook shows linear molecules, with the parent shape trigonal bipyramidal, with the bonds in a "straight" line (180 degrees) and then two lone electron pairs on top and one lone pair on the bottom. What I'm wondering is that wouldn't the two lone pairs on top repel the bonds more strongly than the one lone pair on the bottom? Why are they equal?

Title: Re: Lewis diagrams and perspective drawings
Post by: sjb on October 18, 2009, 04:11:00 PM

The two sets of lone pairs that are on top, are not really in the same plane. What you have is, for instance atoms at the north and south pole, and at the centre of a sphere; then the lone pairs are on the equator, equally spaced, at say 0 deg longitude, and 120 deg W, and 120 deg E.