Non-metals are elements that don't belong to the class of metals, which can conduct electricity, normally shiny, and react with acids. Hence, if your material is not one of the elements listed in the related link, it has to be a non-metal.
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All of the Noble Gasses are non metals.
a mixture of two or more meatals and nonmeatls is alloy
Generally anions. (e.g. Cl-, F-, O2-, N3-)