What are the main differences between what the space filling model and the ball and stick model each show most clearly?

The difference between them is that instead of sticks representing bonds, as in the ball and stick model, the spheres that represent atoms are fused together and the size of the sphere represents the size of the actual atom.

Explanation:

atomic number of carbon is 6

electronic configuration of carbon is 1s²2s²2p²

orbital diagram of carbon is as shown here in the image.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3