It mostly comes down to the amount of bonds between atoms.
Solid objects have connecting bonds that holds each atom to the structure. To break a solid object like a desk you have to break a lot of bonds to do it.
Liquids and vapors on the other hand might have some bonds between atoms, like H20 or N2. In these cases the whole structure is not connected together by these strong bonds, which allows a freedom of movement of the atoms. This is why you can easily push your hand through water or air.
Hope this helps.
Click Here to return to the search form.