Atom
in mental philosophy, a particle of matter so infinitely small that it cannot again be subdivided. In natural philosophy, one of the exceedingly minute ultimate particles of matter, aggregates of an immense number of which, held in their place by moceedingly minute ultimate particles of matter, aggregates of an immense numbodies. ATOMIC WEIGHTS atom cannot exist in a separate state, which an element can be divided. An but unites with one or more atoms to atom cannot exist in a separate state, form a molecule. The atoms of different elements have definite relative weights fixed and invariable for each, the weight of an atom of hydrogen being regarded as unity.