Molecular Geometry - 3D Representations

3D Representations

• Line or stick - atomic nuclei are not represented, just the bonds as sticks or lines. As in 2D molecular structures of this type, atoms are implied at each vertex.

• Electron density plot - shows the electron density determined either crystallographically or using quantum mechanics rather than distinct atoms or bonds

• Ball and stick - atomic nuclei are represented by spheres (balls) and the bonds as sticks

• Spacefilling models or CPK models (also an atomic coloring scheme in representations) - the molecule is represented by overlapping spheres representing the atoms

• Cartoon - a representation used for proteins where loops, beta sheets, alpha helices are represented diagrammatically and no atoms or bonds are represented explicitly just the protein backbone as a smooth pipe

The greater the amount of lone pairs contained in a molecule the smaller the angles between the atoms of that molecule. The VSEPR theory predicts that lone pairs repel each other, thus pushing the different atoms away from them.