Particles are fundamental entities that are used by scientists to explain different types of phenomena. Learn more about them, subsequently testing your knowledge with a quiz.
Definition of a Particle
Imagine picking up a rock and smashing it with a hammer so that it breaks up into smaller fragments. Then, successively break each of the fragments into even smaller fragments, until the resulting pieces are so small that they cannot be further broken down. These non-breakable fragments are one example of particles.
A particle refers to a quantity of matter that is used by scientists to construct theories about their field of study. There is no particular size restriction on defining a particle. Astronomers can define particles to be stars in the night sky, while physicists can define particles to be electrons. It mostly depends on the scientific field and theory under development.
Particles Properties and Classification
You may ask, 'If there is such a large variety of objects that can be thought of as particles, is there a common theme among all of them?' Well, there is, and we will now discuss it.
Scientists often think of particles as point-like objects, meaning that they are considered shapeless for the purposes of the theory. For example, when a chemist is studying the properties of gas particles in a container, he or she would think of them as little shapeless objects that bounce against the walls of their container. If an engineer is studying traffic flow on a busy street, he or she would consider all the vehicles to be particles, disregarding whether a particular vehicle is a bus, car, or motorcycle.
Although all of the previous examples described particles in motion, it is important to note that particles can be permanently stationary objects, at least for the purposes of the theory. For example, the carbon atoms that make up graphite, a primary constituent of pencil lead, can be thought of as particles. Let's briefly discuss atomic and subatomic particles, which are very important in many scientific fields.
Democritus, an ancient Greek philosopher, had a thought experiment similar to the example with the rock fragments. If you take any piece of matter and keep dividing it in half, you will eventually reach a point where it could no longer be divided. He called these indivisible particles atoms.
It's important to note that the scientific definition of an atom is quite different from that of Democritus. As defined in the Encyclopedia Britannica, an atom is the smallest unit into which matter can be divided without the release of electrically charged particles. Although atoms, as we think of them in modern times, have an internal structure, they are often treated as particles that are the building blocks of all matter and chemical reactions. As of today, scientists discovered 118 types of atoms, as can be seen in the periodic table. These atoms can bond together to form molecules, which are structures that contain two or more atoms held together. Subsequently, molecules form more complex structures that ultimately make up all the things that we see around us.
In some cases, atomic particles are insufficient to describe physical phenomena. In these instances, scientists classify smaller-than-atom objects as particles, also known as subatomic particles. Let's look at a few examples.
Electrons are subatomic particles that are often used by electrical engineers to explain, at the most basic level, how digital devices, such as complex as computer chips, function. Protons and neutrons are subatomic particles that are used in many scientific theories. They also constitute the nuclei of atoms. There are many other types of subatomic particles, some of which have been discovered not too long ago. Who knows, maybe you will discover another one.
As we have seen today, particles can be thought of as point-like objects that describe the phenomenon under study. They can be very large, such as celestial bodies, or very small, such as electrons. They can even be objects we observe in the real world, like cars moving down a highway. As long as it describes the movement of units, a particle can really be anything. Despite all this, though, particles themselves can be thought of as being shapeless. However, particles can be stationary, such as atoms (as defined by Greek philosopher Democritus, a piece of matter that can no longer be divided) in a crystal, or in constant motion, such as grains of sand in the wind. We have also discussed atomic (like the single units of the elements on the periodic table) and subatomic particles (like protons and neutrons, which make up the nuclei of atoms and electrons, which orbit the nuclei), which are the constituents of all matter. Can you think of some other examples of particles?