Properties of Matter Investigation 2

Density Density is a property of elements and compounds. It defines how much matter exists in particular space. Density of matter depends on two things, mass and volume. Density can be calculated by using the following formula: Density= mass/volume OR Density= mass÷volume

Density The units for density are g/cm3 . In order to use the formula for density, you must first measure the mass and volume of a substance.

Chemical Properties A property that describes how the atoms of a substance react with atoms of other substances. What are atoms? A tiny particle of matter. It is the smallest particle of an element that has the properties of the element. What are molecules? Two or more atoms joined together.

Chemical Properties What are compounds? What is a mixture? When two or more different elements combine, they form a compound. What is a mixture? A mixture forms when two or more substances are mixed together but their atoms are not combined. The parts of a mixture are easily separated. Example: Fruit Salad

Compounds Unlike a mixture, a compound is made of different elements whose atoms are combined. The particles of a compound always have the same number and kind of atoms. What are solutions? A solution is a special kind of mixture. The substances in a solution dissolve or separate into their more basic particles. These particles are too small to be seen. The substances in a solution can be solids, liquids, or gases.

Chemical Properties You observe chemical changes when a substance is being changed. For example when wood burns, it changes into smoke, heat, and powdery gray or white ash.

Chemical properties Wood has the chemical property of being able to burn in air. During burning, particles that make up the wood react with oxygen in the air and change into other substances such as carbon dioxide, ash, and water vapor.

When a substance changes into something else, both its physical properties and chemical properties change. Describe the different physical properties between fire and ash.

The ash has new chemical properties too. Wood’s chemical properties are that it can burn in air and that it can change into ash, carbon dioxide, and water vapor. Ash doesn’t burn, and if it changes into other substances, they won’t be the same ones that wood changed into. Like ash, carbon dioxide and water vapor have different chemical and physical properties than wood.

Why do I need to know about chemical properties? Their properties are what make elements, compounds, and mixtures useful. Knowing about chemical properties can help in identifying elements and compounds. For example: Pyrite or “Fool’s Gold”

Physical Change When a physical change takes place, the substance that changes does not become a different substance.

Chemical Change A chemical change is a change that forms a new substance. Example: Wood becoming ash and smoke

More Chemical Change Examples: A green tomato turns red when it ripens. Chemical changes cause its color, flavor, and texture to change. A cake bakes. The gluey batter changes into a spongy solid that tastes great!

Chemical Reactions Some chemical changes such as baking a a cake, result from many steps. Each step is a chemical reaction. A chemical reaction is a process that produces one or more substances that are different from the original substances. Chemical reactions are always taking place in the world around you. (Ex: rust)

Chemical Reactions When you eat food, chemical changes take place as you digest it. Digestion is a series of complex chemical changes, each consisting of many chemical reactions.

Review What is the difference between a physical property and a chemical property? Describe three examples of a chemical change. What is a chemical property of iron? How is a chemical change different from a physical change?