This graphic (supposedly) represents the bonding mode of carbon. One of the reasons all life forms are carbon-based on this planet is that carbon can make four bonds arranged in a totally symmetrical tetrahedron shape, with the angle between any two of these bonds being 109.5 degrees.
This diagram has pictured it incorrectly. The carbon is shown in the center of the bottom square plane. That’s not where it should be. It should be floating in the center of the tetrahedron (which the figure above is not). Those H-C-H angles are labeled as 109 but they appear to be 90.
You’d think if they were making a science poster they’d get the actual geometry right. The figure above is not even a tetrahedron (4 vertices), it’s a square pyramid (5 vertices). A square pyramid has one square face and four triangular face; a tetrahedron only has four triangular faces. I’ve been staring at that figure above for awhile wondering if I was just missing something or seeing it wrong, but I don’t think I am. Four of the vertices are labeled H, the one in the center with the dotted lines to is it labeled C, and one is just…not labeled. If we assume it’s H then this molecule would be CH5, which…is impossible under normal conditions.
This is what carbon’s bonding actually looks like.
^ Thank you.
(Source: rivarius)
