Spheres
Appearance

Representation
[edit]To enable the spheres representation do the following for any selection SEL,
show spheres, SEL
Adjusting Sphere Size
[edit]alter selection, vdw=number
Examples
[edit]Shrink the size of all Iron atoms:
alter elem fe, vdw=1.0
rebuild
Dramatically enlarge all spheres in an object
alter object, vdw=4.0
rebuild