2 or more atom bonded together
Molecules
Chemical bond
Connection between atoms
The representation of an object
Model
The atoms (by way of letters and number) that make up a molecule
Chemical formula 
Specific ways that atoms are arranged 
Chemical structure
Structure of atoms or molecules in a 3-D pattern 
Crystal
Structures of molecules in a representing chain pattern 
Polymer
A molecular whose atoms occur in a constant ratio and repeating pattern 
Extended structure
A quantity relationship between two things 
Ratio
Is a sample of matter that has specific chemical and physical properties, such as appearance, melting point, and reactivity. Pure substance are made up of only one type of matter throughout
Pure Substance
A pure substance made of two or more different types of Atoms
Compound