The chemical symbol (not formula) of phosphorous is P; the chemical symbol (not formula) of chlorine is Cl.
Also phosphorous is the ion (PO3)3-.
Formula: PCl3
Formula: P2O3
The formula (symbol) for aluminum is Al. The symbol for phosphorous is P. The formula for aluminum combined with phosphorous is AlP (aluminum phosphide).
P4Se3
Phosphorous Trioxide
The formula for phosphorus trichloride is PCI3.
Phosphorous Trioxide
PFl5
PCl3
Phosphorous Hydride = PH3