The last fundamental topic in Unit 2 is the study of elements, compounds, and mixtures. An element is a type of atom; they are found on the periodic table (ex. iron). A compound is a group of elements bonded together; they have one distinct chemical formula (ex. water – H₂0). A mixture is a combination of various compounds; it cannot be described by one distinct formula (ex. orange juice).

Today in class students traveled around the room examining seven different substances: water, charcoal, soda, vitamin-C, air, grass, and wood. Using their observational skills and a dash of common sense, they tried to classify each substance as an element, a compound, or a mixture. The results were somewhat surprising.

Only one of the substances was a pure element (charcoal). Only two of the substances were compounds (water and vitamin-C). And just like in real life, most of the substances were actually mixtures… even air! Air is composed of several different compounds (CO_2, N₂, O₂, etc.). And that means that, even though you might not be able to see the differences, it is actually a mixture.

October 23 – Elements, Compounds, and Mixtures (pg216)

This weekend’s HW is the Unit 2 Checkpoint Quiz. To take it, please click here. When you finish, your score will automatically be emailed to Mr. A.