Iggy's Element Bonanza! Element: Sodium Atomic Symbol: Na Atomic Number: 11 Iggy: Sodium is another one of the Alkali Metals, it is also more reactive in water than Lithium is. When combined with Chlorine, you get salt! It is soft and can be cut with a knife. Sodium burns a bright yellow flame when put in a flame! Sodium is monoisotopic with one stable isotope, Sodium-23.