Concept: Characteristic Properties 1 Discovery Communications, LLC of Matter

Getting to Know: Characteristic Properties of Matter Take a quick look around you. How many different things can you see? In truth, the answer is too long to list. We are surrounded by things, including things we cannot see, like air. Our minds are constantly working to classify and sort the things we see around us, but they all have one thing in common: all of the things around you (even the ones you cannot see) are matter.

What exactly is matter? Matter is anything that has mass and takes up space. Even the air around you has mass. That is why gasses are considered matter, too. All matter is made of atoms. Most matter on Earth is in three forms: solid, liquid, and gas. There are several other states of matter, like the gel in your toothpaste or plasma, the superheated state of matter produced in lightning. Scientists (and students) make detailed observations about characteristics of matter. In this lesson, you will explore physical and chemical properties of matter.

What are the different physical properties of matter? The physical properties of matter are the things that can be measured and observed without changing the substance itself. There are several different physical properties of matter that

you will learn about and explore in the lesson, including color, odor, and density. Other physical properties include solubility, melting point, boiling point, and electrical conductivity.

Let us look at a few physical properties in closer detail right now. Solubility is the ability of one substance, called a solvent, to dissolve another substance, called a solute. Often, scientists use water to determine the solubility of a substance. For this reason, water is sometimes called “the universal solvent.” When you stir sugar crystals into a glass of iced tea, you are able to observe that sugar (the solute) is very soluble in the water (the solvent).

Electrical conductivity is the ability of a material to transmit an electrical current. A material like copper has high electrical conductivity, which is why it is used in the wiring of a house.

Materials that do not conduct electricity are called insulators. Can you think of any common insulators? Glass is an insulator as is rubber. Electrical currents do not flow through these materials.

Solubility is a physical property of matter.

Concept: Characteristic Properties 2 Discovery Communications, LLC of Matter

Misconception 1: Why aren’t size and mass physical properties of matter?

Size and mass are not physical properties of matter. That is because the amount of the sample does not affect the properties it has. A house-sized piece of quartz that is thousands of kilograms has the same physical properties as a pea-sized piece of quartz that is only a few grams. Both are white and opaque and take the form of six-sided crystals. Both have the same chemical structure: silicon dioxide or SO2. Both cannot dissolve in water at normal temperatures, have a melting point of 1670° C, and leave white streaks when rubbed against a surface. In fact, if you kept breaking down a piece of quartz until it was too small to see, it would have the same the physical properties.

What are the different chemical properties of matter? As you already know, matter is made of atoms. Different elements and compounds, which are combinations of elements, have different chemical properties. The number and arrangement of the subatomic particles (protons, neutrons, and electrons) in atoms determine their chemical properties. Chemical properties relate to the ability of a substance to form chemical bonds with other substances or break bonds within the substance. The most common chemical properties are acidity (ability to form an acid), basicity (ability to form a base), combustibility (ability to form bonds with oxygen and burn), and reactivity (ability to form bonds with other substances). Unlike physical properties, which can be observed without changing the substance, chemical properties can only be observed when a substance undergoes a chemical reaction. During a chemical reaction, a substance changes into a different substance. For example, when wood is burned, that is a chemical reaction. The wood changes into smoke and ash. After it is burned, we cannot restore the wood to its original form.

This wood is undergoing a chemical change called combustion.

Misconception 2: Aren’t boiling and freezing chemical properties of matter?

No, boiling and freezing are not chemical properties of matter; they are physical properties. That is because boiling and freezing are physical changes that can be reversed. Neither boiling nor freezing changes a substance into a different substance; it simply makes its molecules move more quickly or slowly. This is not always the case, however. Sometimes heat can change the characteristic properties of matter. Other things that can alter the properties of matter include pressure, radioactive decay, or electromagnetic energy.