In severe cases of poison ivy, poison oak, or poison sumac, it is a good idea to see a doctor. Sometimes large blisters need to be drained and sometimes an oral steroid such as prednisone may be useful. Systemic steroids produce rapid resolution of both the itching and the rash.
Crystalline solids have a highly ordered arrangement of constituent atoms, ions or molecules in a three-dimensional layer or lattice giving rise to distinct geometrical shapes. Thee are two important types of crystalline solids. 1  Ionic solids (represented by sodium chloride).
A crystal or crystalline solid is a solid material whose constituents, such as atoms, molecules or ions, are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. crystal is a solid where the atoms form a periodic arrangement. (Quasicrystals are an exception, see below .). Not all solids are crystals. For example, when liquid water starts freezing, the phase change begins with small ice crystals that grow until they fuse, forming a polycrystalline structure.