Elements and Compounds

1. Elements and Compounds • Elements • All particles are alike • The smallest particle of an element that is still recognizable is called an atom • They can’t be broken down anymore without completely destroying it (nuclear explosion) • They are found on the periodic table • Currently there are about 118 elements • Chemical symbols are used to represent the elements • Example: C=carbon, N=nitrogen…..

4. Compounds (over 10 million exist) • Two or more elements chemically combined • Once combined, the properties of a compound are different than the elements that make it up! • They can be broken down in the elements that made them up. • Example: Sugar is C6H12O6 • made up of carbon, hydrogen, and oxygen • looks nothing like C, H, O by themselves • can be broken down when burned • A molecule is a type of compound

6. Chemical Formulas • A way to represent chemical substances • Example: Al2O3is aluminum oxide • The subscript2 means there are 2 aluminums • The subscript3 means there are 3 oxygens • Example: 3H2O • The coefficient 3 in front of H2O means there are 3 water molecules. • H2O + H2O + H2O = 6 hydrogens and 3 oxygens total

8. Chemical Equations • Describe a chemical reaction or process • The following are the same process: • carbon dioxide and water  sugar and oxygen • CO2 + H2O  C6H12O6 + O2 • Balancing equations • CO2 + H2O  C6H12O6 + O2 is NOT balanced • The number of each atom must be equal on both sides of the equation. • In order to balance an equation, you can only add coefficientsNOT subscripts. • 6CO2 + 6H2O  C6H12O6 + 6O2 IS balanced