Shape of Molecules

The valence shell electron pair repulsion theory is what is used in order to predict the shape of a molecule. The number of lone pairs and bonded entities present in a molecule will determine it's shape. In particular, we focused on five of the molecular shapes: linear, bent, tetrahedral, trigonal planar, and triganol pyrimidal. A linear molecule has a central atom, consisting of no lone pairs, with two bonded entities. Bent molecules also have two bonded entities but the central atom has two lone pairs. A tetrahedral shaped molecules consists of a central atom with four bonded entities. A molecule without lone pairs on the central atom and three bonded entities is trigonal planar. Lastly, a molecule that is trigonal pyrimidal contains a central atom with two lone pairs and three bonded entities.



We also went over resonance in this lecture. Resonance occurs when a molecule has multiple bonds that can be moved throughout the molecule with the same resulting charges. The picture below shows resonance occurring in an NO3 molecule. Resonance equalizes both the bond strength and the bond length throughout the molecule.



Molecular Shapes Practice
resonance practice