Matter

All the material on earth is in three states-solid; liquid, and gas. The "state" of the matter refers to the group of matter with the same properties. In other words, you group the objects together according to their properties. Solids are usually hard because their molecules have been packed together. The closer the molecules are, the harder the object. Solids also can hold their own shape. A block of wood is a solid. A solid has a certain size and shape, although you can change the shape of solids. For example, you can change the shape of wood by sawing it in half or burning it. The particles of a solid are arranged in a tight, regular pattern, and more very little. Liquid has a size and volume meaning it takes up space. Milk is an example of a liquid, therefore does not have a definite shape. It takes the shape of its container. Liquids can flow, be poured, and spilled. The particles of a liquid move past one another easily. They are close together, but not in a neat, even arrangement as the particles in a solid are. A gas is matter that has no definite shape, size or color of its own. The particles of gas move rapidly and there are much larger spaces between them than between the particles in a liquid or solid.

There are two kinds of mixtures; heterogeneous and homogeneous. A heterogeneous mixture is unevenly mixed. An example of this would be a mixture of oil and water. A homogeneous mixture, however, is mixed very evenly. An example of a homogeneous mixture would be powdered iced-tea mix and water.

Physical changes are about energy and states of matter. Chemical changes happen on a molecular level. When you step on a can and crush it, you have forced a physical change. The shape of the object has changed. It wasn't a change in the state of matter, but a change in shape. When you melt an ice cube, you have also forced a physical change by adding energy. That example caused a change in the state of matter.