Pure Chemical substances

Pure Substances- a sample of matter, either a single element or a single compound that has definite chemical and physical properties

Element- a substance that cannot be separated or broken down into simpler substances by chemical means; all atoms of an element have the same atomic number

Types of pure substances:

1.  
   1.  

      • Elements

      • Compounds

1. Elements- 

                    elements are pure substances that contain only one kind of atom
   1. Has its own unique set of physical and chemical properties
   2. Has its own chemical symbol
   3. Molecule- the smallest of a unit of substance that keeps all of the physical and chemical properties that of the substance; it can consist of one atom or two or more atoms bonded together
   4. Diatomic elements- two of the same atom bonded together chemically

2. Pure Substances

-Some elements have more than one form

-Allotrope- one of a number of different molecular forms of an element

-Compounds are Pure Substances

Compound- a substance made up of atoms of two or more different elements joined by chemical bonds