Classification of Matter: Study with Video Lessons, Practice Problems & Examples

Chemistry is the study of matter, defined as anything that occupies space and has mass. Matter is classified into three types: elements (composed of one kind of atom), compounds (two or more different elements chemically bonded), and mixtures (elements and/or compounds physically mixed). Pure substances have a single composition, while mixtures can be homogeneous (uniform) or heterogeneous (distinct parts). Understanding these classifications is essential for grasping fundamental chemical concepts and reactions, such as acid-base reactions and the properties of various compounds.

Classification of Matter

Hey, everyone. In our journey to understand chemistry, it's first important to define what chemistry is. Now chemistry is the study of matter and the changes it undergoes, with the atom being its basic functional unit. Matter itself is anything that occupies space and has mass, and when it comes to matter, we can group it under three types. We're going to say the first one is the simplest type of matter that is composed of one kind of atom. That would be our elements. Okay. Now when we say element, you might have heard of it. If you've taken chemistry before, you might have heard of the periodic table of elements. We'll go into that in greater detail later on, but just realize that when we're talking about an atom, we're oftentimes referring to those elements on the periodic table. Next, we have matter composed of two or more different elements that are chemically bonded together. So here we're talking about two or more elements, that means we're talking about compounds. So a compound is when you have two or more elements connected together chemically. Then finally, we have matter that is composed of elements and/or compounds that are physically mixed together. The keyword here being mixed. So here, this would be our mixtures. So a mixture would be the third type of matter. Now that we've grouped matter into these three types, let's continue onward and further talk about these groupings.

Classification of Matter

So when it comes to the classification of matter, it all begins with its composition. We ask ourselves, is it a single composition or a variable composition? Now if it has a single composition, that means it's composed of a single type of substance. It's not mixed with another one. And if we're dealing with a single composition form of matter, then we label that a pure substance. Next, we ask ourselves, is this separable into simpler substances? If the answer is no, then it represents an element. Now, remember, from up above, an element is a type of matter composed of one kind of atom. Now a good example of this would be carbon. Carbon uses the symbol C. We'll learn about the symbols and element names later on, but for right now, carbon uses the letter C. It is an element because it's made up of one kind of atom, a carbon atom. Now, oxygen exists as O₂ and although there are 2 oxygen atoms, it's still an element because it's still made up of only one kind of atom, oxygen atoms. There just happens to be two of them. We also have Phosphorus, which in nature is P₄ and Sulfur, which is S₈. The natural forms of these elements we'll also talk about later on when discussing the periodic table. But for now, realize all of these are elements because each of them is composed of only one kind of atom. Some of them are by themselves, like carbon, and in the others, there could be multiple of that same kind of atom. Now if our pure substance is separable into simpler substances, then we'll say that it's a compound. A compound is composed of 2 or more different elements chemically connected together. A good example is something we know, water. Remember water is H₂O. It's made up of 2 hydrogen atoms and 1 oxygen atom. We also have, carbon dioxide, which we breathe out, which is made up of 1 carbon atom and 2 oxygen atoms. Then we have something a little bit less known, a natural sugar, glucose. Glucose is C₆H₁₂O₆. It's made up of different elements together, carbon atoms, hydrogen, and oxygen. So glucose would fall under the definition of a compound. Now if our matter is composed of variable composition, that means it's different substances mixed together with the keyword being mixed. This means that we're dealing with mixtures. With mixtures, we ask ourselves, does it have a uniform composition where everything looks the same in the mixture or is it not uniform? If it's not a uniform mixture, it will be composed of different substances and we can tell them apart. This would be called a heterogeneous mixture. A great example is oil and water. The saying is oil and water don't mix. That's because if you were to take some water and pour some oil in it, shake it up, and then lie it down on a table, eventually you will be able to tell what part of the mixture is oil and what part is water because, again, oil and water don't mix. We can tell the different parts involved within the mixture. Now if it has a uniform composition, then it is a homogeneous mixture or homogeneous mixture. A great example of this is all around us, air. Air is a homogeneous mixture because air is composed of a lot of different things, but all of it looks the same to us. It's composed of oxygen, nitrogen, argon, carbon dioxide, carbon monoxide, as well as other things. It's a lot of different components, but everything looks the same. That is what a homogeneous mixture is. So remember, when it comes to classification of matter, looking at it from a macro view, we look at its composition first. From there, we go into pure substances and mixtures, which will help us identify the 3 major types of matter we talked about above. Now that we've gone over matter, let's go on to the next video.

Which of the following statements is true?

• A. Compounds can only be broken down by chemical means.
• B. Gasoline is a pure substance.
• C. Only elements are pure substances.
• D. Milk is an example of a homogeneous mixture.
• E. Concrete is an example of a homogeneous mixture.

Choose the homogeneous mixture from the list below.

• A. Soda
• B. Smog
• C. Trail mix
• D. Blood
• E. Air

Choose the homogeneous mixture from the list below.

• A. Chicken noodle soup
• B. Coffee
• C. Sand
• D. Fruit salad
• E. Seawater

Classify each of the following as an element, compound or mixture.

a) Ammonia, NH₃

b) Gold bar

c) Orange juice

d) Wine

e) Saline solution

So here we need to classify each of the following as an element, a compound, or a mixture. For the first one, we're dealing with ammonia, which has the formula NH3. It's made up of nitrogen and 3 hydrogen atoms. It's different elements chemically bonded together, so it is a compound. Next, we have a gold bar. It's made up of pure gold, so it's a pure substance. And because it's just gold, one kind of atom, it has to be an element. Orange juice is made up of a liquid portion, sugar, orange concentrate, and pulp. It's different things mixed together, so it's a mixture. The same can be said for wine. Wine typically has in it water, grapes, some sugar, maybe balanced out with some salt. It's different things, again, mixed together. So it is a mixture. Then, finally, we have a saline solution. You see those IV bags in hospitals that are hooked up to patients? Saline solutions traditionally are made up of water and sometimes electrolytes, medication. Because it's made up of different things together, mixed together, a saline solution represents a mixture. So just remember, when it comes to the classification of matter, we can group it based on its composition.

Here’s what students ask on this topic:

What is the difference between an element and a compound?

An element is a pure substance composed of only one kind of atom, such as carbon (C) or oxygen (O₂). Elements cannot be broken down into simpler substances by chemical means. A compound, on the other hand, is a pure substance composed of two or more different elements that are chemically bonded together. For example, water (H₂O) is a compound made of hydrogen and oxygen atoms. Compounds can be broken down into their constituent elements through chemical reactions.

What are the main types of mixtures and how do they differ?

Mixtures are classified into two main types: homogeneous and heterogeneous. A homogeneous mixture has a uniform composition throughout, meaning the different components are not distinguishable. An example is air, which is a mixture of gases like oxygen, nitrogen, and carbon dioxide. A heterogeneous mixture has a non-uniform composition, where the different components can be easily identified. An example is oil and water, where the oil can be seen floating on top of the water.

How can you distinguish between a pure substance and a mixture?

A pure substance has a single, uniform composition and includes elements and compounds. For example, pure water (H₂O) is a compound, and pure gold (Au) is an element. A mixture, however, consists of two or more substances physically combined and can have variable compositions. Mixtures can be either homogeneous (uniform composition) or heterogeneous (non-uniform composition). For instance, saltwater is a homogeneous mixture, while a salad is a heterogeneous mixture.

What is a homogeneous mixture and can you provide an example?

A homogeneous mixture is a mixture with a uniform composition throughout, meaning the different components are not distinguishable. An example of a homogeneous mixture is air, which is composed of various gases like oxygen, nitrogen, and carbon dioxide, but appears uniform to the naked eye. Another example is salt dissolved in water, where the salt is evenly distributed throughout the solution.

What is a heterogeneous mixture and can you provide an example?

A heterogeneous mixture is a mixture with a non-uniform composition, where the different components can be easily identified and separated. An example of a heterogeneous mixture is a salad, where you can see and pick out the individual ingredients like lettuce, tomatoes, and cucumbers. Another example is oil and water, where the oil can be seen floating on top of the water, making the different components distinguishable.