as you have learned about the states of matter in high school, there are three states of matter (just assume i know nth about plasma or any other things else first), and when change of states occur energy is supplied to the matter to increase its potential energy while keep kinetic energy constant. my question is that, why the change of states happen discretely but not continuously as temperature increases?(energy can be supplied to increase both KE and PE) Why there are three states instead of two states? my guessed answer for the second question is: there are more than one kinds of intermolecular forces between each molecules , for example, water molecules have van der waals' force and hydrogen bond, so as temperature increases, van der waals' force is broken so ice is changed to liquid water, and when the temperature further increases hydrogen bond is also broken so there is no intermolecular forces anymore so liquid water is changed to water vapor. And substance like iodine has only van der waals' force, so as temperature increases, it sublimes to gas. Is my answer correct?