Question

What is the difference between 1 gram o2 atom and 1 g atoms of o2 and 1gram-atom of o2 ?​

Answer 1

First of all there is nothing like such called 1 gram atoms. You have to understand the mole concept first. Let me explain that first.

Practically we cannot use one atom for experimental measurements so for that we consider a collection of elementary particles a one unit called mole. Mole is simply like a dozen(12) or gross(14). But the only difference is that it is a collection of elementary particles(ions, molecules,atoms).

1 mole of any element when not stated is taken as 6.023×10^23 molecules. When this collection is taken the R.A.M of the element changes to gram.

for eg: 1 mole of O2 has 6.023×10^23 particles and it's weight is 32g

1 gram of O2 atom has 6.023×10^23/32 atoms.

While 1 gram atom of oxygen has weight =16g and has 6.023×10^23 atoms. This is the difference.