We explain what physical phenomena are, their characteristics, what types exist and various examples. Furthermore, chemical phenomena.
What are physical phenomena?
Physical phenomena or physical changes are called changes in the state of matter that occur without altering the chemical composition of the same, since they do not involve any type of chemical reactions. In the latter they are precisely distinguished from chemical phenomena. Most of them are reversible.
Physical phenomena involve the set of forces that ordinarily affect matter, as well as its change of state of aggregation: liquid, solid, gaseous or plasma. They can also have to do with the mixture of substances, as long as they are heterogeneous mixtures, in which solvent and solute do not present any type of permanent molecular bond.
See also: Chemical changes
Characteristics of physical phenomena
Physical phenomena, in principle, are observable with the naked eye since the state of matter tends to be modified macroscopically. This is even more true for reversible physical changes.
However, in this type of phenomena the amount of matter is not altered That is, the change does not imply a profound transformation of it, nor its creation or destruction, but simply the transition from one state to another, or from one structure to another.
Types of physical phenomena
Physical phenomena can be different, depending on their origin, usually in one of the physical forces of the universe. That way, we can talk about:
- Motion It occurs when a body changes its rest position and moves from one point to another, or when it alters its trajectory and acquires a new one. All of this as the effect of some type of force on it, be it gravity, the impact of some other body, etc. This is what happens when things fall to the ground, for example.
- Heat It has to do with the level of energy present in a body, that is, the speed and intensity with which its particles shake. Objects with greater internal energy will have higher temperatures, and those with lower energy will have a lower temperature. By adding heat to a body, it is possible to induce a change of state of aggregation, as when we boil water and turn it into a gas, or when we freeze water and turn it into a solid.
- Light Electromagnetic radiation from energy sources such as the sun affects matter, generating various phenomena. For example, the color of things is the result of light hitting objects and reflecting a single color among all those that make up the spectrum.
- Magnetism Some metals (especially those linked to iron) have the ability to attract or repel other metals, due to their electronic configuration. These types of reactions do not alter the repelled or attracted metal, they simply rearrange the most superficial particles of its atoms.
- Electricity Electricity and magnetism are closely related, since they come from the properties of the electrons in the atoms of matter. But electricity, unlike magnetism, can be transmitted through certain materials known as conductors. Electricity is nothing more than the difference in electrical potential between one point of matter and another, which generates an electronic displacement capable of being converted into other forms of energy: heat, light, movement, etc. A simple example of this is lightning: violent compensations of electrical potential between the atmosphere and the ground.
- Sound The rhythmic vibration of certain bodies is capable of generating sound waves that are transmitted in air or water, thus generating sounds perceptible to the human or animal ear. The properties of sound depend on the vibrating matter and the medium of wave propagation. This is what happens when church bells are rung.
Examples of physical phenomena
Some simple examples of physical phenomena constitute it the changes of states of water. In its natural state and at ordinary atmospheric pressure, water is liquid and transparent, just as it is when we drink it. If we add heat, heating it in a container, once it reaches 100 °C the water will evaporate, converted into a gas (steam).
If, on the other hand, we remove heat from it by putting it in a freezer, once it reaches 0 °C the water will begin to crystallize and eventually turn into a solid (ice). All of these processes are reversible through the reverse mechanism: adding or removing heat.
Physical phenomena and chemical phenomena
As we said initially, the difference between physical phenomena and chemical phenomena has to do with the type of change caused in matter. In the first case, it is a change of structure, of state, in which the substance remains chemically the same. For example, frozen water is still made up of hydrogen and oxygen.
Instead, chemical phenomena reorganize the molecular nature of matter building and destroying atomic bonds and creating new substances. This is because a chemical reaction occurs, generally irreversible, in which substances totally different from the initial ones are obtained.
For example, metals that react with oxygen oxidize losing some of its properties, without the oxygen being recovered, nor the transformed metal.
References
- “Physical phenomena and chemical phenomena” (video) in Academia Internet.
- “Physical phenomena” in Portland Public Schools (Spanish).
- “Physical and chemical phenomena” on Tintero.com.
- “Physical phenomena” in Encyclopedia.net.au.
