The alpha form of polonium (Po) has a density of 9.196 g/cm³ and crystallizes in a simple cubic structure. What is the atomic radius of polonium? A)119 pm B)168 pm C)266 pm D)335 pm E)419 pm

Question

Quizplus · Accepted Answer

For simple cubic structure, the relationship between density (d), atomic mass (M) and atomic radius (r) is given by:

d = (4M)/(a^3 * Na)

where a is the length of the edge of the cube and Na is Avogadro's number.

For a simple cubic structure, a = 2r. Therefore:

d = (4M)/(8r^3 * Na)
r = [(4M)/(8 * Na * d)]^(1/3)

The atomic mass of polonium is 209 g/mol, and Na is 6.022 × 10^23 mol^−1. Substituting the given values, we get:

r = [(4 * 209)/(8 * 9.196 * Na)]^(1/3) = 168 pm

Therefore, the correct answer is B.

The Alpha Form of Polonium (Po) Has a Density of 9.196