Further testing and observations are made and a new model is formulated.
It is covered with sulfur or sulfur compounds due to extensive volcanic action.
The number of collisions with the sides of the container would increase causing an increase in pressure.
The number of collisions per unit area of the container would decrease resulting in a decrease in pressure.
They provide a three dimensional model of the molecule which is often more realistic than flat two dimensional drawings. They can be used to make predictions about possible uses for the compound (drugs).
One molecule must fit precisely in another in order for a reaction to occur. This is common in enzymes (catalysts in living systems).
They were used from the molecular level to the solar system level (with Io - Jupiter's moon).