Have you tried to put a Sphere into an Atom-Array-Object
and maybe set Cylinder-Radius to 0.5 and Sphere-Radius to 1.
I presume one could animate this nicely.
well, I presume you have to extend your Timeline –
Go to Edit/Project-Settings and choose your
Framerate and Minimum/Maximum-Frame.
You can then set Keyframes in your choosen area
in the F-Curve-Manager or Timeline