The concept of SCP (Secure, Contain, Protect) is part of a fictional universe created by the SCP Foundation, which features a vast collection of anomalous objects, creatures, and phenomena. While SCP articles provide detailed information about many entities, the scale of atoms in the SCP universe is not explicitly defined.
The SCP Foundation focuses on containing and studying anomalies rather than delving into specific scientific details such as the scale of atoms. SCP entries often explore supernatural or anomalous properties that defy conventional scientific understanding. Therefore, it is difficult to provide a definitive answer about the scale of SCP atoms without specific information from a particular SCP entry.
It's important to remember that SCP articles are works of fiction and are not based on real-world science. The SCP Foundation universe is designed to be mysterious and eldritch, often defying traditional scientific explanations.