Physical and Chemical Changes of Matters
The change of matter is divided into “physical” and “chemical”. Changes seen only in the external structure of matter are physical. In a chemical change, a change is observed in the identity of the substance, that is, in its internal structure.
Physical Change
It ıs the change that can be noticed through observation. The color or shape of the substance changes. Physical changes are collected in 8 main groups.
1. Breaking
Example: breaking wood, breaking ice, breaking an egg
2. Dissolution
Sugar is made up of carbon, hydrogen, and oxygen atoms. The atoms of sugar dissolved in water do not change.
3. Change of State
It is the physical change of matter due to temperature. Example: Water freezing from liquid to solid, ice melting from solid to liquid
4. Crumbling
Human factors are effective in the physical change of matter by crumbling. Example: Grating carrots, grinding coffee
5. Expansion – Contraction
Depending on the temperature increase, the length of solid and liquid substances changes. In some substances, both length and volume increases are observed. Shrinkage occurs as a result of the cooling of materials. The structure of the material and the rate of heat it is exposed to are the factors that determine the amount of expansion and contraction. Example: expansion of a metal plate, contraction of steel
6. Tearing
Example: Notebook paper tearing, clothes tearing
7. Mixture
The combination of two or more substances is called a mixture. For example, when sand and water are mixed, the appearance of both substances changes. But there is no change in atoms and molecules.
8. Physical Digestion
Digestion of food begins in the mouth. Food products that are broken down by teeth are examples of physical change.
Chemical Change
Both physical and chemical changes occur in every substance that undergoes changes in atoms or molecules. For example, tearing a piece of fabric causes it to physically change. However, if the fabric is burned, it has changed chemically since it no longer has the fabric feature. There are 10 types of chemical change.
1. Fermentation
Fermentation of milk into yogurt is a chemical change.
2. Decay
Also known as decomposition. It consists of three stages, namely swelling, active decay, and advanced decay. Example: rotting of vegetables such as peppers, tomatoes, and onions
3. Combustion
New atoms such as carbon dioxide and water are formed in burning materials. For this reason, the combustion of substances leads to a chemical change, not a physical one.
4. Corrosion
Some materials wear out over time. This leads to rust. Rusting iron and silver is a chemical change.
5. Cooking
All kinds of food cooked at high temperatures undergo chemical changes.
6. Respiration
Oxygen taken in cellular respiration turns into carbon dioxide. In respiration, which is seen in all living things, the atom changes chemically.
7. Chemical Digestion
If food is digested in large pieces, this is called mechanical or physical digestion. Chemical digestion is the breaking down of food into smaller pieces by enzymes.
8. Photosynthesis
Photosynthesis by plants is a chemical change.
9. Chemical Reaction
The formation of a new substance as a result of the combination of two substances is called a chemical reaction or reaction.
10. Mold
Bacteria and fungi cause materials to become moldy. Example: Bread molding
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