Iggy's Element Bonanza! Element: Phosphorus Atomic Symbol: P Atomic Number: 15 Iggy: Phosphorus is found in 2 major forms, White and Red Phosphorus and 4 minor forms, P2, Violet, Black, and Scarlet Phosphorus. White Phosphorus is not stable and is always changing to Red Phosphorus. Red Phosphorus is stable and can be found on the side of a matchbox. Phosphorus has one stable isotope, P-31.