science 5

Chemical change can be brought about by heat, light, electricity or the presence of another substance.
Chemical change occurs when two or more substances react chemically and produce a new substance.
         Conditions that bring about chemical change
                a. burning - absorption of heat
                b. addition of vinegar to milk - presence of another substance
                c. taking photographs - light
               d. gold plating - electricity
New materials are formed when chemical change occurs. these materials are called products.
The product of a chemical change cannot be brought back to its original form.
Physical change differs from chemical change in that the former does not involve any change in composition.

Everything in the environment is changing.
 The different changes that occur in the environment have varied effects.
Some of these changes are beneficial while others are harmful.
1. Matter undergoes two changes: physical and chemical.
2. Physical change happens when there are changes in sizes, shapes, or states. The change is only in the appearance. The composition of matter remains the same.
3. Changes in the state of matter are: evaporation, condensation, melting, solidification or freezing and sublimation.
4. Chemical change is accompanied by a change in the composition of matter. It results in the formation of a new substance.
5. Changes in the environment bring about beneficial and harmful effects. Soil pollution, water pollution and air pollution are among the harmful effects. Technology has made the lives of some people easier and more comfortable.
6. Pollution brings about ailments to humans. It deteriorates the normal functions of living and non-living things.
7. Much can be done to help save the planet Earth from further damage. Take good care of the environment so that life could continue to thrive on Earth.