Atoms, Elements and Compounds

• All substances are made of atoms
• An atom is the smallest part of an element that can exist
• Compounds are formed from elements by chemical reactions.
• Chemical reactions always involve the formation of one or more substances, and often involve a detectable energy change
• Compounds contain two or more elements chemically combined in fixed proportions and can be represented by formulae using the symbols of the atoms from which they were formed.
• Compounds can only be separated into atoms by chemical reactions