1) Molecular compounds - two or more non-metals elements/atoms coming together
2) Ionic compounds - one type of metal element/atom and one type of non-metal coming together
Actually, how you determine if a set of elements coming together is a MC or IC entails more understanding than stated above. These details will be discussed or taught in a separate location.
Chemical Formula
A question one may have is, How many atoms of each element is coming together to form these compounds?
Chemists have a short hand method to show this called Chemical Formulas.
Def Chemical Formula - a way of showing what elements are coming together and how many of each.
The chemical formula uses the chemical symbol of each element and a subscript that indicates how many atoms of each element are coming together to form the compound. Here are two examples including their chemical name:
1) Na1Cl1 - Sodium chloride (an Ionic compound).
2) C1O2 - Carbon dioxide (a Molecular Compound).
For our purposes here, you can say that:
1) In one ionic compound's base unit of Na1Cl1, there is one atom of Na and 1 atom of Cl (not actually correct but will explain elsewhere).
2) In one molecular compound's base unit of C1O2, there is one atom of C and two atoms of O. (this is actually correct).
This is very important to understand in chemistry because the chemical formula can be seen as analogous to words (combinations of letters to represent "something") in languages.
Molar Mass - Expanding Mole Concept of Massing to Any substance