The shape of an atom. is

spherical
square
pyramifal

The shape of an atom is spherical

spherical

Explanation:

In 1911, Rutherford proved with his experiment that the spread of positive, and negative particle inside the atom wasn't uniform. It was assumed to be uniform according to the atomic model given in 1904 by J.J. Thomson.  

According to the latest atomic model, the atom has a dense nucleus made of neutrons and protons in the rest state whereas; the electrons revolve around the atomic nucleus in its respective orbital orientations.  

The shape of an atom depends upon the electron's angular momentum and the electrostatic force between the atomic particles. Since the atoms don't have well defined spherical boundaries because of various orbital orientations around the nucleus, their shape cannot be stated as spherical.

However, only simple atoms exhibit spherical shape and not the complex ones.

molecules are free to separate from each other and will take on the shape of the container. molecules move completely at random and high speeds. they vibrate in a fixed position and do not move around much. molecules expand to the edge of their container.