| ISOTONE | One of two atoms with equal neutrons and nonequal protons |
| ISOTOPE | One of two or more atoms with the same atomic number but with different numbers of neutrons |
| ALPHAPARTICLE | Composite particles that are made up of two neutrons and two protons bound tightly together (5,8) |
| NUCLEUS | Positively charged central core of an atom composed of neutrons and protons |
| ATOM | Tiny unit of matter, made of protons, neutrons and electrons. (4) |
| ISOTOPES | Atoms with the same number of protons but different number of neutrons (8) |
| OCTETS | Oxygen's protons, neutrons and electrons |
| DOUBLEBOND | Molecular link with two pairs of electrons shared by two atoms |
| FUSION | The reaction that powers the Sun and other stars, where two atoms of hydrogen combine |
| DIOXIDE | Molecule containing two atoms of oxygen |
| BENZENERING | Closed chain of six carbon atoms with hydrogen atoms attached |
| WATER | Compound combining two hydrogen atoms with one oxygen atom (5) |
| ALPHA | Type of particle with two protons and two neutrons (5) |
| CRYSTAL | From the Greek meaning "ice" or "frost", an array of atoms with an ordered internal structure and plane faces, such as diamond or quartz (7) |
| RADICAL | In chemistry, an atom or atoms with at least one unpaired electron (7) |
| IONS | Atoms with more protons than electrons or vice versa |
| TOMATOES | Fruits of splitting atom with parts of foot? (8) |
| IMIDE | What is a compound derived from ammonia by replacing two hydrogen atoms with acyl groups? (5) |
| BOHRIUM | Synthetic transuranic element discovered in 1976 by bombarding bismuth-209 atoms with ions of chromium-54; atomic number 107 (7) |
| INERT | Like atoms with complete valence shells |
