Instead of beta-plus emission, an inner atomic electron is captured by a proton in the nucleus.

The particle may be an ordinary atomic electron, so emission coefficients have practical applications.

The momentum of the particles is reduced as they ionize atomic electrons in the material.

The breakdown field depends on the density and how tightly held are the atomic electrons.

In addition, one has to take into account that the atomic electrons are not stationary ("shell correction").

Some atomic electrons circling around the gas and metal atoms are excited by these collisions, bringing them to a higher energy state.

So this is where the comparison of orbiting atomic electrons to orbiting planets breaks down.

So no, Kepler's laws do not apply to atomic electrons.

(An exception to this rule can occur for tightly bound atomic electrons.)

Because this interaction takes place on atomic electrons it occurs with the same rate in both the heavy and light water.