1. different form of an element.   symbiosis   isotope   pestle   trough   Hint Half-n-half Clue   2. product of mass and velocity for a moving body; impetus.   patina   summation   iota   momentum   Half-n-half Clue   3. terminology or method of naming.   spectrum   magnitude   nomenclature   psychosis   Half-n-half Clue   4. small opening of cavity.   molecule   orifice   spatula   metamorphosis   Half-n-half Clue   5. sleeplessness.   sextant   insomnia   refraction   vise   Half-n-half Clue   6. primary type used as model.   panacea   nutrient   residue   prototype   Half-n-half Clue   7. partly lighted shadow.   yield   repulsion   whorl   penumbra   Half-n-half Clue