Matter can be described and identified by physical and chemical properties. Physical properties have to do with appearance. You can observe many physical properties with your senses and by measuring the length, width , height, mass and density of a substance. Physical properties include color, shape, smell, texture, taste and size. The state of matter (whether it's a solid, liquid , or gas) and the temperature at which the substance boils, melts or freezes are also physical properties. Magnetic properties are physical properties as well.
Chemical properties, on the other hand, have more to do with the atomic or molecular composition of matter. Chemical properties deal with how substances react with other substances such as water, air or fire.
A physical change has occurred when a substance changes color, size, shape, temperature or state. A chemical change has occurred when a substance has changed into something new or different so that the original substance is gone. Digestion and combustion are examples of chemical changes. A chemical change takes place in a battery to produce electricity when you turn on a flashlight.
Chemical changes are sometimes represented by a chemical formula:
2H2 + O2 = 2H2O
This formula states that two hydrogen gas molecules react with one oxygen gas molecule to produce two molecules of water.