Phosphide itself is not much. I think what you mean is the phosphide ION. The formula for phosphorus is P, as you must know, but the phosphide ion is P3- ( the ionic charge being in superscript)
And it is so because when bonding, Phosphorus will gain three more electrons to complete its full octet as before bonding, it only has 5 electrons in its valence shell.
The chemical formula for Phosphorus Difluorochloride is PF2Cl.
The chemical formula for phosphorus trifluoride is PF3.
The chemical formula for phosphorus pentiodide is PI5.
The chemical formula for red phosphorus is P4.
The chemical formula for phosphorus sulfide is P2S5.
The chemical formula for phosphorus mononitride is PN.
The chemical formula for boron is B, while the chemical formula for phosphorus is P.
The chemical formula for phosphorus acid is H3PO3.
The chemical formula for Phosphorus Difluorochloride is PF2Cl.
The chemical formula for phosphorus trifluoride is PF3.
The chemical formula for phosphorus pentiodide is PI5.
The chemical formula for phosphorus triiodide is PI3.
The chemical formula for phosphorus hydrogen is PH3.
The chemical formula for red phosphorus is P4.
There is no "formula" for "calcium and phosphorus". The symbol for calcium is Ca; the symbol for phosphorus is P. You'd have to specify an actual compound in order to get a formula.
For sulphur its S and for phosphorus its P
The chemical formula for phosphorus sulfide is P2S5.