Matter: What Everything Is Made of
The “stuff” that the physical world is made of is called matter. The word matter is used in science to refer to physical substances in general. Matter occupies space (volume) and has mass, especially as distinct from energy. The opposite of matter is space or void. Matter is not things like mind, spirit or energy. We use our five senses to understand matter, particularly sight and touch.
When we learn about matter, we must talk about kinetic energy and volume. Kinetic energy is manifested in the motion of an object. Changes in energy cause changes in states of matter. Volume, or how much space something takes up, is important because similar “amounts” of matter take up different volumes.
The term particle is useful when learning about matter. Particle is used as a generic, non-exact word for any thing. Grains of sand, dust, and salt can all be called particles, as can cookie crumbs or the rainbow jimmies on ice-cream. In science, particles can refer to cells, molecules, atoms (and the parts that they are made of), as well as subatomic particles like neutrinos and quarks. We cannot see with our unaided eyes the extremely tiny bits that everything is made of. They are microscopic. Micro- comes from a Greek word mīkrós, which means little, small, short and/or insignificant. The symbol for micro is μ. A scope (-scopic) is a lens that helps our eyes see something better. Microscopes let us see things that are extremely tiny.
Atoms
All matter is composed of extremely tiny particles called atoms (Greek: άτομο, “unable to cut”). Atoms are the most basic building blocks of all the matter in the universe. Most of an atom is void (empty space) but they are constructed of even smaller particles called protons, neutrons, and electrons. The center of the atom is the densest part, the nucleus, where the protons and neutrons are. Protons have a positive charge and neutrons are neutral. These two parts are held together by a force called the nuclear force (aka the strong force). The nuclear force is the strongest of the four fundamental forces (the others are gravity, electromagnetism, and the weak force) but it can only act over very short distances. Nuclear energy gets released when the nucleus is either split apart (fission) or collapsed together (fusion). If a nucleus could be enlarged a billion times, it would be about the size of a grapefruit.
The electrons in atoms are extremely interesting for many reasons. Electrons are much smaller than the particles in the nucleus. They are negatively charged which causes them to be attracted to the protons in the nucleus. They hover around outside of the nucleus and the attraction between their negative charge to the positive change of protons holds the atom together as a distinct particle. If the nucleus was the size of a golf ball, the electrons would be between one-half and six miles away from it.
Atoms can have different numbers of protons, neutrons, and electrons. The atom types based on these numbers are called elements. All the elements that we know are itemized on the Periodic Table which is organized by how many protons they have in their nucleus from the least, Hydrogen (symbol, H protons: 1) to Oganesson (symbol, Og protons: 118). Scientists are always on the lookout for undiscovered elements and so the Periodic Table can expand as needed.
Atoms can exist in the pure, elemental state or they can combine with each other. When they do this, they form molecules. When atoms come together to form molecules, their properties (characteristics) change. For example, when two Hydrogen atoms join an Oxygen, they make water. Before joining each other, Hydrogen and Oxygen are gases, but together they form water, which we know as liquid, solid (ice), and gas (steam). There are innumerable combinations of atoms which form molecules. No matter what their combination, matter exists in four states, solid, liquid, gas, and plasma.
Plasma
Plasma is the most unusual of the four states of matter. Plasma is a gas which has so much energy that some of the electrons in its atoms break free from, but travel with, their nucleus. Gases can become plasmas in several ways but all include the gas gaining energy. A spark in a gas can create a plasma. Plasmas are the most abundant state of matter in the universe because some of the most massive objects in the universe, our sun and most other stars, are made of it. While it is interesting, plasma is rare on Earth and is studied very little at the elementary school level.
Solid
The solid state of matter makes up the things that we can hold and touch, like bricks, furniture, iPads, and hamburgers. Particles in solids have a low amount of energy, but they are not still. Particles in solids wiggle and vibrate in place but do not easily change their location. Solids have a definite shape and a definite volume. Solids are typically easy to see and feel firm (hard, like a rock or soft, like a cotton ball), although solids can be malleable (squishy).
Liquid
Particles in the liquid state take the shape of their container (a solid). For example Sprite fills the bottom of a bottle, latex contains the water in a balloon, veins and arteries contain blood. If a liquids are not in a container, (spilled on the floor, table, etc.) they spread out. Particles in liquids have a much higher level of energy than particles in a solid. They slide around and move past each other. Liquids have a definite volume, i.e., take up a definite amount of space, but not a definite shape of their own like a solid. Liquids are typically easy to see and usually feel wet.
Gas
Gases are usually invisible to the naked eye. They sometimes can be detected through our sense of smell, though not always. The particles of a gas are high in energy which causes a high level of activity. Because of this, gas particles will spread out if not inside a (solid) container. Gases have neither a definite volume nor shape.
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