Subject: Are all atoms the same size by volume?

Taking into account we measure everything comparatively speaking by some 
common volume and record its weight, it would seem to me that atoms would 
all have to be the same size by volume.  Other wise their weights would be 
incorrect. Using the age old pun, which is heavier a 100 lbs of lead or a 
100 lbs of feathers, the answer is obvious as for they both are equal. But 
they're not equal in volume.  Furthermore, what would you get if you put 
100 lbs of feathers into a container that only holds exactly 100 lbs of 
lead. The answer, the 100 lbs of feathers would turn into lead, as your 
compression of these feathers would require changes at the atomic level. 
Thus forcing all the feather atom nuclei together resembling that of 
lead.  Am I right or wrong?

Re: Are all atoms the same size by volume?