EDIT : This issue is already fixed in the latest atom releases.
Running atom on a terminal will show you why:
/usr/share/atom/atom: error while loading shared libraries: libXss.so.1: cannot open shared object file: No such file or directory
This solution for this is simple. Just install the following package:
$ sudo dnf install libXScrnSaver
Seems that this RPM build is missing some dependencies. The bug is already reported here.