Final answer:
Phospholipids are amphipathic molecules with a hydrophilic head and hydrophobic tail. In a membrane, the hydrophilic head faces the outside while the hydrophobic tail faces the inside.
Step-by-step explanation:
A phospholipid is an amphipathic molecule, meaning it has a hydrophilic and a hydrophobic part. The head is composed of the hydrophilic phosphate group, and the tail contains the hydrophobic fatty acids. In a membrane, a bilayer of phospholipids forms the structure's matrix, phospholipids' fatty acid tails face inside, away from water; whereas, the phosphate group faces the outside, aqueous side.