What are the Four States of Matter?

Jun 9, 2021

3 min read

What is Matter?

Everything around us is made up of matter. Matter is made up of atoms and molecules. How the atoms or molecules move determines if matter is a solid, liquid, gas, or plasma. These are the four phases of matter, also known as the four states of matter.

The atoms or molecules in a solid are stuck in one place. They vibrate, but they cannot escape their position.

The atoms or molecules in a liquid move freely, but they are stuck together. It is difficult for an atom of liquid to leave the other atoms. As a result, liquids flow.

The atoms or molecules in a gas move freely and do not stick together. The atoms or molecules in a gas will spread until they fill any container.

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Thermal Energy and the Four States of Matter

Thermal energy is the energy of atoms or molecules moving. Every atom and molecule has thermal energy, and they are all moving. The higher the temperature of an object, the more its atoms or molecules move. For example, the water molecules in an ice cube are very cold, so they can only vibrate in place, but the water molecules in a cloud of steam are very hot. They spread throughout a room.

Atoms and molecules will stop moving if their temperature is cold enough. Absolute zero is the temperature at which atoms and molecules stop moving. It is -273.15°C. Scientists have not yet cooled anything to absolute zero, but they are trying.

A substance’s melting point and boiling point are determined by how much energy it takes to get its atoms or molecules moving. In general, it is more difficult to move larger molecules, but many factors affect melting points and boiling points.

Phase Changes and the Four Phases of Matter

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States of matter are also called phases. As the temperature of a substance changes, its state changes too. Moving from one state of matter to another is called a phase change.

Each type of phase change has a different name.

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Examples of phase changes are all around us. The water cycle is especially helpful for learning about them. During evaporation, liquid water becomes water vapor. The water vapor moves up through the atmosphere. When the temperature drops, the water vapor condenses back into liquid water and forms clouds. Liquid water falls back to the ground as rain. If the temperature is cold enough, the rain freezes and becomes snow.

Sublimation and deposition are rarer than the other phase changes because they take an extreme temperature change to skip the liquid phase. Dry ice is an example of sublimation. At room temperature, a block of solid carbon dioxide will immediately transform into a vapor. Morning frost on the grass is an example of deposition. The overnight temperature was so cold that the water vapor in the air transformed directly into tiny crystals of solid ice.

The Fourth Phase of Matter: Plasma

While most people know about the three phases of matter, there is a fourth phase that happens when atoms and molecules have even more thermal energy than during the gas phase. The plasma phase of matter happens when a gas becomes so hot that electrons are stripped away from their atoms leaving behind positively charged ions and negatively charged electrons.

Plasma makes up 99% of the visible universe. It also makes up most of our solar system because the Sun is made up of plasma. Lightning also turns the air around it into plasma, and neon signs are full of neon plasma.

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Scientists want to learn more about plasma because it has weird properties, including the ability for plasma elements to undergo nuclear fusion, as they do in the Sun. By learning more about plasma, scientists can learn how to use plasma to make our lives better.

Phases of Matter Digital Science Unit

Do you really want to learn about the three phases of matter? Then, you need to do more than read about it. You will need opportunities to process what you learn. If you want to remember it, you need opportunities to practice remembering it. That’s why my digital science unit on the three phases of matter includes review activities, flashcards, comprehension questions, and a quiz. You can get the digital science unit at Teachers Pay Teachers. Click the image below to check it out!