Elements, Compounds, and Mixtures Hopper 7th Grade Science

An element is a substance made from one type of atom An element is a substance made from one type of atom. It cannot be changed into another element or anything simpler using chemical reactions. Remember only elements are found on the periodic table. Elements

Compounds The atoms of the different elements can join together in chemical reactions to form compounds.

Molecules Molecules consist of two or more atoms joined together. Compounds

Formula for Compunds

Mixtures A mixture is made from different substances that are not chemically joined together.

Mixture of elements and compounds Diagram Description Pure element Pure compound Mixture of elements Mixture of compounds Mixture of elements and compounds

Your table should have 2 columns and 11 rows. Draw a table on your paper. Make sure the table covers all the lines on one side of a paper. Your table should have 2 columns and 11 rows.

Chemical Card Drawing

Select a Chemical Card that is on your table. Record which chemical card you are using on your table. Using the pasta create a model on your colored paper of the compound you selected. Once the teacher has check your model draw it on your data table. Continue until you have drawn all the compounds.

What is a limitation of modeling compounds in this way? Answer these questions in complete sentences on the back of your paper. Describe how your models are similar to the chemical formula given on the chemical card. What is a limitation of modeling compounds in this way? Are H20 and H2O2 the same compound since they are composed of the same two elements? Are CO2 and CO the same compound since they are composed of the same two elements?

Summary Mixture Compound Composition Joined or not Properties Variable composition – you can vary the amount of each substance in a mixture. Definite composition – you cannot vary the amount of each element in a compound. Joined or not The different substances are not chemically joined together. The different elements are chemically joined together. Properties Each substance in the mixture keeps its own properties. The compound has properties different from the elements it contains. Separation Each substance is easily separated from the mixture. It can only be separated into its elements using chemical reactions. Examples Air, sea water, raisin bran cereal. Water, carbon dioxide, magnesium oxide, sodium chloride. Summary