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Molecular Models
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Ball and Stick Model
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A ball-and-stick model is a 3D representation of a molecule.
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Ball-and-stick models help us understand how each atom is bonded in a molecule. It uses a line or stick to represent
the covalent bonds between atomic nuclei.
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The basis of the ball and stick model is Valence Bond Theory.
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Ball-and-stick models also show relative bond lengths and ideal bond angles.
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They help us to visualize the molecular geometry
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Physical models cannot show deviations from the ideal bond angle because they cannot model lone pairs.
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Space Filling Model
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The Space-filling model also provides a 3D representation of a molecule.
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It is "space-filled" due to the lack of visible lines connecting the atoms. Instead, the atoms are placed on each other
(without using the visible bond lines).
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The sizes of the atoms are proportional to the atomic radii of that atom. For example, oxygen will look larger
than hydrogen due to its larger radius.
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The Space-filling model is based on the Molecular Orbital Theory.
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Computational chemists and biochemists use computer programs to create space-filling models.