What new characteristic did John Dalton add to the model of the atom? An atom is a round, solid mass. An atom has a massive, positive center. An atom is made up of smaller particles. An atom can join with other kinds of atoms.

Atomic Theory. Learn vocabulary, terms, and more with flashcards, games, and other study tools ... thinking about the smallest particles of matter without experimenting. Click again to see ... What new characteristic did John Dalton add to the model of the atom? An atom can join with other kinds of atoms.