SB 3.11.1
maitreya uvaca
caramah sad-visesanam
aneko ’samyutah sada
paramanuh sa vijñeyo
nrnam aikya-bhramo yatah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The material manifestation’s ultimate particle, which is indivisible and not formed into a body, is called the atom. It exists always as an invisible identity, even after the dissolution of all forms. The material body is but a combination of such atoms, but it is misunderstood by the common man.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The atomic description of the Srimad-Bhagavatam is almost the same as the modern science of atomism, and this is further described in the Paramanu-vada of Kanada. In modern science also, the atom is accepted as the ultimate indivisible particle of which the universe is composed. Srimad-Bhagavatam is the full text of all descriptions of knowledge, including the theory of atomism. The atom is the minute subtle form of eternal time.