Density The ratio of the mass of a substance to the volume of the substance M:V mass volume http://www.brainpop.com/science/matterand chemistry/measuringmatter/
3 most familiar states of matter solid, liquid, and gas. For example, water commonly exists in three states of matter: solid (ice), liquid (water), and gas (steam). http://www.brainpop.com/science/matterandchemistry/states ofmatter/
The ice, liquid water, and steam are all the same substance—water.
A change of state is the change of a substance from one physical form to another. All changes of state are physical changes. In a physical change, the identity of a substance does not change.
Solids Have Definite Shape and Volume The particles in solids move so slowly they can not overcome the attractions between them.
Liquid is the state of matter that has a definite volume but takes the shape of its container. The particles in liquids move fast enough to overcome some of the attractions between them. The particles slide past each other until the liquid takes the shape of its container.
Gas is the state of matter that has no definite shape or volume The particles of a gas move quickly. They can break away completely from one another. There is less attraction between particles of a gas than between particles of the same substance in the solid or liquid state.
Melting: Solid to Liquid One change of state that happens when you add energy to a substance is melting. Melting is the change of state from a solid to a liquid.
Gallium melts at about 30°C. Because your normal body temperature is about 37°C, gallium will melt in your hand! Table salt, however, has a melting point of 801°C, so it will not melt in your hand. pg75
Freezing: Liquid to Solid The change of state from a liquid to a solid is called freezing. The temperature at which a liquid changes into a solid is the liquid’s freezing point. Freezing is the reverse process of melting. Thus, freezing and melting occur at the same temperature.