In this topic you will learn about how the physical properties of matter can be described.

Any solid, liquid, or gas is called matter. Matter is the "stuff" that makes up the world. You can measure an object's mass by trying to push or pull it.

Mass is a measure of how hard it is to push or pull an object. The more mass an object has, the harder it is to push or pull. The amount of the pull of gravity between an object and Earth is called the object's weight. Objects with more mass also have more weight.

The amount of space taken up by an object is called its volume. Scientists often measure volume of solids in cubic centimeters, or cm3. A cubic centimeter is the volume of a cube that measures one centimeter on each side. A graduated cylinder is used to measure liquid volume. The unit shown on a graduated cylinder is a milliliter, or mL (1 mL = 1 cm3).

The amount of mass in a certain volume of material is its density. You can find the density of an object by finding the mass, finding the volume, and dividing the mass by the volume. When an object is placed in a less dense liquid or gas, the object will sink toward the bottom. If the liquid or gas is more dense, the object will float toward the top.

Objects can be described by their properties. Properties are things you can observe with your senses. Some properties include color, hardness, odor, and shine. A physical property is a property that can be observed without changing the identity of a substance. Properties such as color, odor, and density are physical properties.

When a substance changes from solid to liquid or liquid to gas, it is changing its state. A physical change is a change of size, shape, or state without forming a new substance. Mixing things together is a type of physical change.

A solution is a mixture of one substance dissolved in another so that the properties are the same throughout. There are many kinds of solutions. Solutions may contain any combination of solids, liquids, and gases.

A chemical change is a change in matter that produces new substances with properties different from the original substances. Chemical changes often show one or more key signs. A color change may occur, heat and light may be given off, a gas may be produced, or a powdery solid may form.

The mass of matter does not change during chemical changes. The total mass of all starting substances equals the total mass of all new substances in chemical changes.