Here are some examples of chemical compounds:
water,
carbon dioxide,
octane,
ethanol,
methane,
sucrose (white sugar),
calcium carbonate (limestone),
sodium chloride,
Each of these substances can be represented by a chemical formula that shows more than one element. A chemical compound is two or more elements chemically joined in a definite proportion, such that the formula is always the same. For example, a water molecule is always two hydrogen atoms chemically bonded to one oxygen atom. All water molecules are the same. Ionic compounds such as sodium chloride don't exist as individual molecules but still have a constant ratio of elements.
A compound differs from an element in that an element has only one type of atom. It differs from a mixture in that a mixture contains particles of more than one type that aren't chemically bonded to each other, can vary in composition and can be separated by physical means such as distillation or filtering.
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