The Model
Water (H2O)
Assuming pressure of this model is 1.00 atm:
Freezing Point: 0℃
Boiling Point: 100℃
The objective of the model is to demonstrate the movement of atoms in each different phase of water. Moving the slider to the right represents adding an increment of heat to the substance to slowly change the substance into the next phase. The movement of atoms defines the phase of water. When atoms are bound closely together by molecular forces to be in a fixed position, the substance is in a solid state. When heat is added to the substance, the molecular forces are weakened and at 0 degrees celsius, melting point, the atoms shift from stationary to free flowing and at this point, the substance has transformed from a solid to a liquid. At 100 degrees celsius, boiling point, the substance has reached its gaseous state and at this phase, the molecular forces are very weak and can no longer hold the particles altogether and so the particles are in an excited state where they constantly zoom and collide each other.