Classification of Matter - Online Tutor, Practice Problems & Exam Prep

Chemistry is the study of matter, which is 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 composition, like air) or heterogeneous (distinct components, like oil and water). Understanding these classifications is essential for grasping fundamental chemical concepts.

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 3 types. We're going to say the first one is the simplest type of matter, 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 often referring to those elements on the periodic table.

Next, we have matter composed of 2 or more different elements that are chemically bonded together. So here we're talking about 2 or more elements, that means we're talking about compounds. A compound is when you have 2 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. A mixture would be the third type of matter. Now that we've grouped matter into these 3 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 oxygens there, it's still an element because it's still made up of only one kind of atom, oxygen atoms. There just happens to be 2 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'll 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, lay 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. 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.

Classification of Matter Example 1

So if we take a look at this example question, it says, consider the following substances. We have Gatorade, crystalline sugar, lead wire, and salsa. And it looks like all our option choices are talking about pure substances or homogeneous mixtures. So, let's go through each one and identify what we have. Gatorade. We all know that this is an energy drink, and it looks like just a single colored liquid, sometimes white, sometimes blue, sometimes red, even yellow. But if we look closer into Gatorade, we'll see that Gatorade is composed of water, sugar, and, of course, what's important, electrolytes. But all of it looks the same. It has a uniform composition. We can't tell them apart. So Gatorade is an example of a homogeneous mixture. Next, we have crystalline sugar. Don't get confused by the word crystalline. That really isn't important. It's just talking about the organized structure of the sugar itself. Now, up above, we talked about biological sugar in the form of glucose. Right? So crystalline sugar is pure sugar, you can think of glucose as a good example. Above we said that glucose was a compound, but more importantly, it was a pure substance. Here we're assuming that it's just pure sugar by itself, not mixed with anything. Lead wire. Here, we're just dealing with one type of atom, lead. We're not dealing with it mixed with anything else. The entire wire is made up of just lead, so this would be an element, more importantly, a pure substance. Finally, we have salsa. So, salsa can come with a lot of different things besides the base tomato part of it. We could have corn in there or green peppers or onions. All we know is that when we look at salsa, no matter what it is, we can tell it has different components in it, and because we can see the different parts of it, it is a heterogeneous mixture. From our choices, we can see option a doesn't work because 1 and 2, 2 is a pure substance, but not 1. 1 and 2 are homogeneous mixtures. No. Only 1 was a homogeneous mixture out of the 2. 2 and 3 are pure substances. We did say that. 1 is a homogeneous mixture. We said that too. Option d can't be the answer because we found out that option c was the correct choice. So, remember, when it comes to the classification of matter, think of it in terms of composition. From there, we can separate it further into the 3 main types that we talked about above. Now that we've done this example question, let's move on forward and continue our discussion on matter and its classifications.

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. Bowl of cereal with milk
• E. Pure oxygen and nitrogen gas

Choose the homogeneous mixture from the list below.

• A. Chicken noodle soup
• B. A cup of black coffee
• C. Sand (unfiltered)
• D. Fruit salad
• E. Seawater (unfiltered)

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 three 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, 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. Examples include water (H₂O), which consists of hydrogen and oxygen atoms, and carbon dioxide (CO₂), which consists of carbon 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 that looks the same throughout. A heterogeneous mixture, on the other hand, has a non-uniform composition, and the different components can be easily identified. An example is oil and water; when mixed, they form distinct layers that can be seen separately.

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

A pure substance has a single, uniform composition and consists of only one type of particle. It can be either an element, like gold (Au), or a compound, like sodium chloride (NaCl). Pure substances have consistent properties throughout. A mixture, however, consists of two or more substances physically combined, and its composition can vary. Mixtures can be separated into their individual components by physical means, such as filtration or distillation, whereas pure substances cannot be separated by physical methods.

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 evenly distributed and not distinguishable. An example of a homogeneous mixture is air. Air is composed of various gases, including oxygen, nitrogen, and carbon dioxide, but it appears uniform and consistent throughout. Another example is saltwater, where the salt is completely dissolved in the water, making it look like a single substance.

What are some examples of heterogeneous mixtures?

Heterogeneous mixtures have a non-uniform composition, and the different components can be easily identified. Examples include oil and water, where the two liquids form separate layers that do not mix. Another example is a salad, where you can see and pick out the individual ingredients like lettuce, tomatoes, and cucumbers. Sand and iron filings mixed together also form a heterogeneous mixture, as the sand and iron can be seen and separated easily.