CLASSIFICATION OF MATTER

Unit Overview

In this unit, you will learn some of the ways in which matter is classified. You will learn how to define matter and classify it as an element, compound, or mixture. You will be able to differentiate between homogeneous and heterogeneous substances. You will investigate different types of mixtures.

What is Matter?

All substances around us are composed of matter. Matter is defined as anything that has mass and takes up space. Water is an example of matter. It has mass and occupies space. Helium gas is another example of matter. Although helium may not seem to have mass or be taking up space, you can prove it takes up space by filling up a balloon with helium. You could measure the mass of the balloon before and after filling it to get the mass of the helium.

Check out the following video to learn more about matter, and how it is different from energy:

What is Matter?

Classification of Matter

Matter is classified into categories based on how it is composed. Three categories for classifying matter according to composition include elements, compounds and mixtures. Mixtures can be further categorized into solutions, suspensions, and colloids. In order to understand the similarities and differences among elements, compounds, and mixtures, you must first understand the most basic building blocks of matter: atoms.

An atom is the smallest building block of matter that cannot be broken down further and still retain the properties of that substance. A molecule is a group of atoms held together by a chemical bond. There can be one or more types of atoms in a molecule. If a substance has only one type of atom, or only one type of molecule, it is known as a pure substance. You will become much more involved in your comprehension of atoms and molecules in the following units, but a basic understanding helps when learning about elements and compounds.

Elements and Compounds

An element is a pure substance that contains only one type of atom throughout the material. Examples of elements include oxygen, carbon, and mercury. Some elements exist as single atoms, where others exist as diatomic molecules. This means that instead of being composed of single atoms, the element has two of the same atom fused together in a molecule. A compound is a pure substance that is made when two or more elements are chemically bonded together. Examples of compounds include water and sodium chloride.

Oxygen atom:

Image result for oxygen atom

Diatomic molecules:

Image result for diatomic molecule

Water molecule:

Image result for water molecule

Heterogeneous vs Homogeneous

Matter can be further classified based on whether the substance’s particles are homogeneous or heterogeneous. Homogeneous substances have the same particles throughout. Heterogeneous substances have different particles in a sample. Elements and compounds are both types of homogeneous substances.

Mixtures

Mixtures are made when two or more elements or compounds are physically combined. Mixtures are not pure substances because they are not the same composition throughout. Mixtures are different from compounds because the components of a mixture are physically combined, but the components of a compound are chemically bonded. Similarly, mixtures can be physically separated, but compounds cannot.

There are different types of mixtures, which are categorized based on the arrangement and size of particles in the mixture. First, mixtures can be either homogeneous or heterogeneous. A heterogeneous mixture has particles that are not evenly dispersed. Examples of heterogeneous mixtures include salad and trail mix. A homogeneous mixture has particles that are evenly dispersed throughout the sample. Examples of homogeneous mixtures are lemonade and mayonnaise.

Image result for heterogeneous homogeneous

Homogeneous mixtures are further divided into types known as solutions, suspensions, and colloids.

Watch the following video on solutions, suspensions, and colloids, and complete the guided notes as you watch. You will attach your answers in question 11.

PRINTABLE VIDEO GUIDED NOTES

	Solution	Suspension	Colloid
Particle size
Particle behavior (what happens to the mixture over time?)
Examples

A solution is one type of homogeneous mixture that is sometimes mislabeled as a compound. A solution is made when a solute (the substance being dissolved) is mixed into and dissolved into a solvent (the substance doing the dissolving). An example of a solution is salt water. The salt is the solute and the water is the solvent. The solution is the combination of solute and solvent, and in this example the solution is the salt water that is made. The salt dissolves and the particles evenly disperse throughout the water in the solution. Because the salt water is a physical combination of substances, and the salt and water are not chemically bonded, it is a mixture and not a compound.

Solute (salt)	Solvent (water)	Solution (salt water)

PhET Simulation

What happens when sugar and salt are added to water? Explore the PhET simulation to further explore solutions. Pour in sugar, shake in salt, and evaporate water to see the effects on concentration and conductivity. Zoom in to see how different sugar and salt compounds dissolve. Zoom in again to explore the role of water. Follow these directions carefully! To run the simulation, click run, download, save and then open.

Click to Run

Laboratory Assessment: Nuts and Bolts

With the information you have learned in the unit, apply what you know to complete the Nuts and Bolts lab test. Download the attached document and use the images below to complete the test. Here are the names of the different pieces used in the samples, so you may correctly refer to them:

Nut:	Bolt:	Washer:

Part I

SUDENT COPY_NUTS AND BOLTS ASSESSMENT

Answer the questions in the first part of the assessment based on what you’ve learned in the unit.

Part II

Now, evaluate these samples. Decide whether each sample contains atoms of an element, molecules of an element, molecules of a compound, a heterogeneous mixture, or a homogeneous mixture.

Sample 1: