Which statement describes an element? Check all that apply.

An element is a pure substance made of one kind of atom that cannot be chemically broken down into a simpler substance, so A is correct. Every recognized element appears on the periodic table, and element symbols begin with a capital letter followed by lowercase letters if there are additional letters, so C and D are correct. B is not a definition of an element: elements can exist as single atoms or as groups of atoms, and chemically combined atoms can also form compounds.

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