1. Chemical Reactions Notes #2

2. What is an element?
One of the basic substances made up of only one kind of atom that cannot be broken down by chemical means into simpler products.
Periodic table of the elements. There are 92 naturally occurring elements.
All matter that we see and use comes from different combinations of these 92 elements.
Examples: Oxygen (O), Hydrogen (H), Iron (Fe)

3. What are compounds?
Compounds are made up of two or more atoms of different elements chemically combined to form something new.
Compounds have different properties than the elements that make them up, for example salt.
Examples of compounds: HCl, NaCl, H2O, H2O2, C6H12O6

4. What is a molecule? Molecules are two or more atoms grouped together.
Molecules can be classified as elements if all atoms are of the same element or as compounds if the atoms of the molecule are different elements.
Examples of molecules: O2, H2, S8, CO2, H2SO4