| Molecule building block | 23 |
| Molecular building block | 24 |
| It's split in a lab | 23 |
| It's smashed in a lab | 25 |
| It's little matter | 22 |
| It's a small thing | 22 |
| It has one or more shells | 25 |
| Fermi's fascination | 23 |
| Diminutive DC superhero | 23 |
| Where a quark is located | 24 |
| What the Bohr model depicts | 27 |
| Unit proposed by Leucippus | 26 |
| Unit in a Brownian model | 24 |
| Thing that might decay | 22 |
| The ___, comics crime fighter | 29 |
| Symbol of the post-1945 age | 27 |
| Supercollider projectile | 24 |
| Subject of Bohr's theory | 28 |
| Splitting it releases energy | 28 |
| Sometimes it's smashed | 26 |
| Sometimes it gets smashed | 25 |
| Smidgen that's smashed | 26 |
| Smallest unit of an element | 27 |
| Quantum mechanics unit | 22 |
| Quantum mechanics model | 23 |
| Particle for a physicist | 24 |
| Particle depicted on an Emmy | 28 |
| Participant in a collision | 26 |
| Nucleus + electrons etc. | 25 |
| Niels Bohr's subject | 24 |
| Niels Bohr's study | 22 |
| Niels Bohr's concern | 24 |
| Nanotechnology subject | 22 |
| Mite that might blight | 22 |
| Minimum amount of an element | 28 |
| Lord Rutherford's concern | 29 |
| Item studied by Niels Bohr | 26 |
| Item once thought indivisible | 29 |
| It's small but lethal | 25 |
| It's a little matter | 24 |
| It splits energetically | 23 |
| It may get smashed or split | 27 |
| Home to a muon or pion | 22 |
| Fluke: "___ Bomb" | 27 |
| First half of the files? | 24 |
| Echobelly song about physics? | 29 |
| Democritus postulated it | 24 |
| Controversial power source | 26 |
| Concern of Compton and Fermi | 28 |
| Concern for Edward Teller | 25 |
| Chemistry class subject | 23 |
| Certain smasher's target | 28 |
| Cartoon character ___ Ant | 25 |
| Building block of physics | 25 |
| Building block of molecules | 27 |
| Basis of all, to Lucretius | 26 |
| Alphabet's first half | 25 |
| A bit that can be split | 23 |
| Kind of clock or number | 23 |
| Type of power or clock | 22 |
| Type of clock or number | 23 |
| Word with power or reactor | 26 |
| Word with particle or pile | 26 |
| Word with age or weight | 23 |
| Word before number or weight | 28 |
| Type of clock or energy | 23 |
| Superprecise, as some clocks | 28 |
| Super hot, as Buffalo wings | 27 |
| Sort of clock or power | 22 |
| Sort of clock or number | 23 |
| Radioactive Blondie song? | 25 |
| Like superprecise clocks | 24 |
| Like some precise clocks | 24 |
| Like some periodic-table data | 29 |
| Like some clocks and bombs | 26 |
| Kind of weight or number | 24 |
| Kind of number or weight | 24 |
| Kind of number or energy | 24 |
| Kind of number or clock | 23 |
| Kind of mass or theory | 22 |
| Kind of bomb since the 1940s | 28 |
| ___ number (proton count) | 25 |
| ___ FireBall (hot candy) | 24 |
| __ energy (nuclear power) | 25 |
| Post-Manhattan Project era | 26 |
| Explosive time in history? | 26 |
| Era that began with a blast? | 28 |
| Couple in the news in 1945 | 26 |
| Reduce to fine particles | 24 |
| Reduce to a fine spray | 22 |
| Components of molecules | 23 |
| What's the matter? | 22 |
| Tiny elemental components | 25 |
| They split when smashed | 23 |
| They might get smashed | 22 |
| Physicist's studies | 23 |
| Molecule's components | 25 |
| Basic building material | 23 |
| "___ for Peace" | 25 |
| Very small building blocks | 26 |