1. B   Boron   Beryllium   Mercury   Gold   Hint Half-n-half Clue   2. Os   Tin   Silver   Osmium   Lithium   Half-n-half Clue   3. Pb   Zinc   Xenon   Lead   Potassium   Half-n-half Clue   4. Co   Nitrogen   Antimony   Cobalt   Fluorine   Half-n-half Clue   5. O   Oxygen   Silicon   Iron   Cobalt   Half-n-half Clue   6. N   Nitrogen   Potassium   Silicon   Phosphorus   Half-n-half Clue   7. Si   Silicon   Platinum   Calcium   Barium   Half-n-half Clue