New experimental data of lattice constants, residual resistivities and magnetic properties (magnetisations and hyperfine fields at phosphorus and iron atoms) are presented and discussed in relation with the electronic structure of phosphorus as dilute impurity in an iron matrix; most of them are in agreement with the appearance of '3sp' virtual bound states near the Fermi level. The iron hyperfine field values compared with those measured in more concentrated amorphous alloys show in both systems a typical dependence with the number of phosphorus atoms as nearest neighbours. A comparison of the whole data with those obtained for other 'sp' substitutional impurities of the same periodic table row (Al, Si) or column (As, Sb) points out the role played by the valence and the period of impurity on the investigated properties.