sentences: an atom is a kind of object & structure is a property of an object ->  structure of an atom is a property of the atom  structure of an atom is a property of the atom & organizing is sorting things in order by their properties ->  structure of atoms can be used to organize atoms in order  structure of atoms can be used to organize atoms in order & atoms of different elements have different structures -> structure of atoms of different elements can be used to organize atoms of different elements