Properties of Matter

There are two properties of matter namely, physical & chemical properties. Physical property is something you can observe without changing the composition of matter. For example, you saw a jar and you said, “That jar is smooth, shiny, and 10 inches in diameter”. Smooth, shiny, and 10 inches are all physical properties of the jar. Physical property can further be divided into two: extrinsic & intrinsic properties. Extrinsic property describes the outside appearance of objects. Smooth & shiny are extrinsic properties of the jar, while 10 inches is the intrinsic property because it describes the measurable aspects of an object.

Physical changes are changes that alter a substance with out changing its composition. An example is melting & solidification. We all know that ice is solidified water. When ice melts, voila! You still have water! Another example tearing a piece of paper; even if you tear the paper into a million tiny pieces, those tiny pieces is still (yep, that’s right!) paper! Boiling water is also a physical change.

Chemical property can be observed when there is a change in the composition of matter (chemical change). An example is burning. When we burn wood, both physical and chemical changes occur. First, you may see the color, shape, & size changing, and then eventually the wood becomes ashes. Rusting & cooking are also examples of chemical changes.

Here are some signs of chemical change:
- formation of gas
- formation of precipitate (insoluble substance)
- liberation or absorption of heat
- distinct change in color
- production of flame
- presence of bubbles

Sometimes, physical & chemical changes are accompanied by endothermic or exothermic reactions. In an endothermic reaction, heat is absorbed by the substance; while in an exothermic reaction, heat is released by the substance to the environment. An example of endothermic reaction is photosynthesis. Plants absorb the heat of the sun in order to make food. Using this example, we can say that in an endothermic reaction, the reactants have lower energy contents than the products (there is an increase in the temperature of the substance). On the other hand, the solidification of water into ice is an exothermic reaction. The reactants have higher energy contents than the products (there is a decrease in the temperature of the substance).