Change in Science
A large part of science is understanding how and why changes occur. Change in science can be classified as a physical or chemical change.
A physical change in a substance doesn't change what the substance is. Examples of physical changes include breaking glass, the chemical makeup of the glass does not change. The broken glass can be reversed by melting the glass and re blowing it. Another reaction that is physical is when ice cream melts. Melted ice cream can simply be refrozen.
In a chemical change where there is a chemical reaction, a new substance is formed. Examples of chemical changes include leaves changing colour in Autumn. The chlorophyll that makes leaves green breaks down, the green colour disappears. At the same time other chemical changes may occur, which form additional colours.
Another chemical change is when silver cutlery becomes dull with black spots. Sterling silver turns black or tarnishes due to a chemical reaction caused by contact with sulfur or hydrogen. Some foods or everyday items containing sulfur can cause tarnishing, but even polluted air can turn sterling silver black.
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