Dominic is holding discourse on atoms. He is listing many humorous ways of looking at atoms. For instance, he says, "If I'm bleeding, atoms are coming out of my body. We're always walking on atoms. I'm sitting on atoms." He's saying "atom" to sound like "Adam" and giggling madly.
It reminded me of something that happened to Gabriel right after we moved here, when Gabriel was in fourth grade. On his first day of school, he read all the names of his classmates. He came home and excitedly informed me that one of the kids in his class was named "Eon." After much discussion, I realized the kid's name was Ian. Gabriel and I were both very disappointed.