Final answer:
Niobium exhibits a body-centered cubic (BCC) crystal structure, where atoms occupy about 68% of the volume. Each cell contains two atoms and an atom has coordination number of eight. Other metals with the BCC structure include K, Ba, Cr, Mo, W, and Fe.
Step-by-step explanation:
The metal niobium exhibits a body-centered cubic (BCC) crystal structure, typical of many metallic elements. In a BCC structure, atoms are efficiently packed, filling approximately 68% of the space within the structure. Each unit cell in a BCC crystal contains two atoms: one atom is located at the center of the cell, and the other is distributed equally among the eight corners of the cell (each corner contributing one-eighth of an atom). This arrangement leads to every atom having a coordination number of eight, meaning that each atom in the structure is in contact with four atoms in the layer above it and four atoms in the layer below it.
Several other metals also have the same isomorphous BCC structure as niobium, including potassium (K), barium (Ba), chromium (Cr), molybdenum (Mo), tungsten (W), and iron (Fe) at room temperature. The BCC and face-centered cubic (FCC) structures are among the most common for crystallizing metallic elements, and they can sometimes be analyzed as interpenetrating combinations of two simple cubic lattices composed of alternating positive and negative ions.