Fission 6 principle that during a chemical reaction the total mass of the system is unchanged 2. fusion 3 the positive ion that results when a hydrogen ion is bonded to a water molecule (h3o+) 3. hydronium 5 a charged atom or group of atoms 4. hydroxide 5 one of two or more atoms of the same element with different masses due to different numbers of neutrons 5. ion 1 the splitting of a nucleus into two smaller nuclei whose combined mass is less than that of the original nucleus 6. isotope 4 a negative ion composed of a covalently bonded oxygen and hydrogen, (oh-) 7. law of conservation of mass 2 the joining of two small nuclei to form one nucleus with a larger mass than the combined mass of the original nuclei

If I am correct then this is a matching question where the term has to be matched with its definition so i am providing definition for each term I can find. Fission - is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts Fusion - fusion is a reaction in which two or more atomic nuclei come close enough to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as the release of large amounts of energy Hydronium - is the common name for the aqueous cation H 3O +, the type of oxonium ion produced by protonation of water. Hydroxide - is a diatomic anion with chemical formula OHâ’. Ion - an atom or molecule with a net electric charge due to the loss or gain of one or more electrons Isotopes - are variants of a particular chemical element which differ in neutron number. Law of conservation of mass - According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.