The phase of an element is largely dependent on the interactions between atoms of the element in pure form. The phase, therefore, can give good clues as to some of the physical properties of the element. For example, the Noble gases are known to be inert, and in being inert they have very little need to attract other atoms, and so their pure forms are always gaseous. Also, most chemical reactions and other interactions are largely dependent on the phases of their constituents. For example, it does little good to try to react a solid with a gas, as very little mixture would result and atomic collisions would be rare.
Some elements are so radioactive that none of their isotopes have ever been found naturally.
It is hard to justify calling them solid or otherwise if a substantial amount of them cannot be obtained. The crystal structure of some elements are also given here. Note that these refer to crystals of the solid form, as liquid crystals are rare. The shapes simply refer to appearance of the bonded atoms at an atomic level. However, it is also very much related to the interactions and attractions between atoms.