Extracellular fluids have relatively high concentrations of sodium (NaÌ), chloride (ClÍ), and bicarbonate (HCOÓÍ) ions.  Intracellular fluid has relatively high concentrations of potassium (KÌ), magnesium (MgÌÂ), and phosphate (POÔÍÃ) ions.  Note: Charged ions can also be indicated by reversing the superscript notation (e.g., MgÂÌ).