What is the difference between atomic structure and crystal structure? Atomic structure relates to the arrangement of protons and neutrons in the nucleus of an atom. Crystal structure pertains to the electron structure of the individual atoms. Atomic structure relates to the number of protons and neutrons in the nucleus of an atom, as well as the number and probability distributions of the constituent electrons. Crystal structure pertains to the arrangement of atoms in the crystalline solid material Atomic structure relates to the number of protons and neutrons in the nucleus of an atom. Crystal structure pertains to the number and probability distributions of the electrons. Atomic structure relates to the number of electrons. Crystal structure pertains to the type of atomic bonding in the crystalline solid material. Iron (Fe) has a BCC crystal structure, an atomic radius of 0.124 nm, and an atomic weight of 55.85 g/mol. What is its theoretical density in g/cm^3? For each of the cubic unit cells shown below, select the letter of the direction vector that is represented by the set of directional indices [101]. A B C