both are pure substances, but atoms represent the smallest bits of elements. compounds are chemically combined atoms, molecules represent the smallest bits of compounds.
atoms cannot be broken down...
An element is a substance that is composed all of the same atom; carbon, oxygen, iron, etc. A compound contains two or more elements (that can be separated by chemical reactions).
a solution is a mixture while a compound is a pure substance. thus, a solution melts or boils over a wide temperature range while a compound melts or boils sharply. a solution has varying composition...