A student recently wrote us: "I am taking the diagnostic test now, and I've noticed what I think is a discrepancy in a couple of answers: 227 question: Water, ammonia, and methane have the same electronic geometry.. This geometry is termed: Answer according to test: Tetrahedral 228 question: The molecular geometry of water is: Answer according to test: Bent How can water have both a bent shape and a tetrahedral shape?"
Water is, in fact, both tetrahedral and bent. The reason is that tetrahedral describes water's electronic geometry, which takes into account its lone pairs of electrons making water have four areas of electron density. Bent describes water's molecular geometry, which does not take into account water's lone pairs of electrons. For the MCAT, it is important to understand on a conceptual level of what molecular and electronic geometries are as well as that they are two different ways to describe the geometry of molecules.
Thanks for your question. I hope this helps!
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