Final answer:
The mass and density of a neon atom are determined using the molar mass, which accounts for the different naturally occurring isotopes and the volume derived from the atomic radius. A neon atom is considerably denser than the neon gas, illustrating the significant empty space between gas molecules.
Step-by-step explanation:
Estimating the mass of a neon atom and calculating its average density can be approached by first determining the molar mass of neon. The molar mass is calculated by taking into account the natural abundance of neon's isotopes: Ne-20, Ne-21, and Ne-22. With 90.92% of atoms as Ne-20 (19.99 amu), 0.3% as Ne-21 (20.99 amu), and 8.85% as Ne-22 (21.99 amu), the average atomic mass can be computed. The mass of a single neon atom in atomic mass units (amu) is equivalent to the average atomic mass divided by Avogadro's number.
To calculate the density, we must consider the atomic radius of neon and assume a spherical shape. The formula for the volume of a sphere (4/3 πr^3) is used alongside the estimated mass to find the density. When comparing this value to the density of neon gas, which is significantly lower, the conclusion is that a neon atom is substantially denser than neon gas. This difference in density emphasizes the vast amount of empty space present in a gas when compared to the tightly packed nature of solids and liquids.