Polonium (atomic mass 209.0 g/mol)crystallizes in a primitive cubic unit cell.If the density of polonium is 9.15 g/cm³,what is the radius of a polonium atom (in pm)? A) 168 pm B) 238 pm C) 336 pm D) 475 pm E) 672 pm

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The density (ρ) of a substance is related to its molar mass (M), the volume of its unit cell (V), and the number of atoms per unit cell (Z) by the formula ρ = (Z*M)/(N_A*V), where N_A is Avogadro's number. For a primitive cubic unit cell, Z = 1. The volume of the unit cell can also be expressed in terms of the edge length (a) as V = a^3. The edge length is related to the radius (r) of the atom by a = 2r for a primitive cubic structure. Given the density and molar mass of polonium, and knowing it crystallizes in a primitive cubic structure, we can solve for the radius of a polonium atom. Rearranging the formula and solving for r gives a radius of approximately 168 pm.

Polonium (Atomic Mass 209