Chemical reactions and stoichiometry

We are now going to delve into the heart of chemistry. We learn ways of representing molecules and how molecules react. To do this, we'll even think about "how many" of a molecule we have using a quantity called a "mole".
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We are now going to look at chemical reactions. But as we do, we need to make sure that atoms aren't magically appearing or disappearing. Put another way, we need to sure that we have the same number of each constituent atom in the product of the reaction as we do in the reactants (the molecules that react)!

Now we are going to draw the connections between balancing equations and what happens in the lab (where you actually have a certain mass of a compound).

We'll now explore two different ways of representing what elements are in a molecule: molecular and empirical formulas. Molecular formulas actually represent the number of atoms in a molecule while empirical formulas show us the ratio of the constituents based on experiments. In order to help us connect these ideas, we'll also explore a quantity called the "mole". Just as a "dozen" represents 12 of something, a "mole" represents roughly 602,200,000,000,000,000,000,000 of something. This will help us think about mass composition of molecules.

In a chemical reaction, atoms get rearranged, combined and separated to form new substances. We will be learning about the different ways reactions can be classified, and the properties of different reaction types.