Molecules are different from atoms because they

An atom is the fundamental(smallest) part of matter, that a chemical element can exist. However it may or may not be chemically stable in nature, due to several factors such as its electronic configuration, imbalance in the force of attraction between the nucleus and electron etc… It can broken down into simpler particle, which can depict the characteristics of an element. An atom represents only a single element.

A molecule is a group of chemically bonded atoms(reacted) which may be of similar elements(H2 molecule, O2 molecule) or different (H2O molecule, HCl molecule), which is formed due to the interaction between atoms in different ways, so as to attain chemical and electrical stability

An iota is the fundamental(smallest) some portion of issue, that a concoction component can exist. Anyway it could conceivably be artificially steady in nature, because of a few factors, for example, its electronic arrangement, lopsidedness in the power of fascination between the core and electron and so fort.

Explanation:

It can separated into more straightforward molecule, which can delineate the qualities of a component. An iota speaks to just a solitary component.  A particle is a gathering of artificially reinforced atoms(reacted) which might be of comparative elements Hydrogen particle, Oxygen atom or extraordinary (H2O atom, HCl atom), or, in other words to the communication between molecules in various routes, in order to achieve compound and electrical security