Arsenic, antimony and bismuth come mainly from sulphide ores such as mispickel, FeAsS, and stibnite, Sb2S3.
The differences arise from lower pp - pp bonding effectiveness replaced by use of the d-orbitals for dp - pp bonding, and gradual increasing stability of the lower oxidation states on descending the group:
Ca3(PO4)2 + 6SiO2 + 10C P4 + 6CaSiO3 + 10CO
The yellow phosphorus, P4 must be collected under water since it inflames in air.
Its structure is a tetrahedron of phosphorus atoms connected by oxygens on th esix edges of the tetrahedron and each carrying a terminal oxygen atom.
P(OR)3 + R'X [(RO)3PR']+X- (RO)2(R')PO + RX
The dialkyl phosphonates produced are structurally similar to phosphorous acid where R replaces H.
nPCl5 + nNH4Cl (NPCl2)n + 4nHCl (Solvents: C2H2Cl4 or C6H5Cl)
Then the chlorine atoms can be replace by alkoxy, alkyl, or aryl groups by reaction with NaOR or LiR reagents. The resulting compounds can be made into useful fibres or elastomers.
2RPCl2 + 2Mg RP=PR + 2MgCl2
RECl2 + H2E'R' RE=E'R' + 2HCl (In the presence of base)