What makes phosphorus unique

Phosphorus is an essential part of life. When combined with oxygen to make phosphates, it holds our DNA together, makes our bones strong and carries out fundamental chemical reactions within our cells. But phosphorus also has its dark side. Pure phosphorus comes in a variety of different forms, differentiated by colours produced by the different ways the atoms can be arranged. There is white phosphorus also described as yellow , red, violet, black — and most recently pink has been added to the list.

The discovery was made by the alchemist Hennig Brandt who was boiling his own urine in search of gold I kid you not. After days of heating up litres of stagnant pee, Hennig managed to isolate a white, waxy solid, which was probably something of a disappointment after his long and olfactorily-challenging work. But his mood must have perked up when it got dark and he observed that this newly-created substance glowed with an eerie green light.

There are two problems with this. The second problem is the flammability of white phosphorus. The person who lay afterwards in the bed, waking at night and feeling more than ordinary heat, perceived that the coverlet was on fire. The ease with which phosphorus and some of its compounds will catch fire has led to suggestions that it might be the cause of spontaneous human combustion. Glossary Common oxidation states The oxidation state of an atom is a measure of the degree of oxidation of an atom.

Oxidation states and isotopes. Glossary Data for this section been provided by the British Geological Survey. Relative supply risk An integrated supply risk index from 1 very low risk to 10 very high risk. Recycling rate The percentage of a commodity which is recycled.

Substitutability The availability of suitable substitutes for a given commodity. Reserve distribution The percentage of the world reserves located in the country with the largest reserves. Political stability of top producer A percentile rank for the political stability of the top producing country, derived from World Bank governance indicators.

Political stability of top reserve holder A percentile rank for the political stability of the country with the largest reserves, derived from World Bank governance indicators. Supply risk. Young's modulus A measure of the stiffness of a substance.

Shear modulus A measure of how difficult it is to deform a material. Bulk modulus A measure of how difficult it is to compress a substance.

Vapour pressure A measure of the propensity of a substance to evaporate. Pressure and temperature data — advanced. Listen to Phosphorus Podcast Transcript :. You're listening to Chemistry in its element brought to you by Chemistry World , the magazine of the Royal Society of Chemistry. Hello - this week fertilisers, fire bombs, phossy jaw and food additives.

What's the connection? Here's Nina Notman. Phosphorus is a non-metal that sits just below nitrogen in group 15 of the periodic table. This element exists in several forms, of which white and red are the best known. White phosphorus is definitely the more exciting of the two. As it glows in the dark, is dangerously flammable in the air above 30 degrees, and is a deadly poison.

Red phosphorus however has none of these fascinating properties. So where did it all begin? Phosphorus was first made by Hennig Brandt in Hamburg in Germany in When he evaporated urine and heated the residue until it was red hot.

Glowing phosphorus vapour came off and he condensed it under water. And for more than years most phosphorus was made this way. This was until people realised that bone was a great source of phosphorus. Bone can be dissolved in sulfuric acid to form phosphoric acid, which is then heated with charcoal to form white phosphorus. White phosphorus has found a range of rather nasty applications in warfare.

It was used in the 20 th century in tracer bullets, fire bombs, and smoke grenades. The scattering of phosphorus fire bombs over cities in World War II caused widespread death and destruction. In July , Hamburg was subject to several air raids in which 25, phosphorus bombs were dropped over vast areas of the city. This is rather ironically considering where phosphorus was first made. Another group of warfare agents based on phosphorus are nerve gases such as sarin.

Sarin is a fluorinated phosphonate that was used by Iraq against Iran in the early to mids. And was also released in a Tokyo subway in , killing 12 people and harming nearly a thousand others.

White phosphorus has also found a wide range of other uses. One of these was in phosphorus matches that were first sold in Stockton-on-Tees in the UK in This created a whole new industry of cheap lights - but at a terrible cost. Breathing in phosphorus vapour led to the industrial disease phossy jaw, which slowly ate away the jaw bone. This condition particularly afflicted the girls who made phosphorus matches. So these were eventually banned in the early s and were replaced by modern matches which use either phosphorus sulfide or red phosphorus.

As well as in matches, today phosphorus has found other uses in lighting. Magnesium phosphide is the basis of self-igniting warning flares used at sea. When it reacts with water it forms the spontaneously flammable gas, diphosphine which triggers the lighting of the flare. Super pure phosphorus is also used to make light emitting diodes.

These LEDs contain metal phosphides such as those of gallium and indium. In the natural world the elemental form of phosphorus is never encountered. It is only seen as phosphate, and phosphate is essential to life for numerous reasons. It is part of DNA, and also constitutes a huge proportion of teeth enamel and bones in the form of calcium phosphate. Organophosphates are also important, such as the energy molecule ATP and the phospholipids of cell membranes. A normal diet provides our bodies with the phosphate it needs.

With tuna, chicken, eggs and cheese having lots. And even cola provide us with some, in the form of phosphoric acid. Today most of our phosphorus comes from phosphate rock that is mined around the world, and then converted to phosphoric acid. Fifty million tonnes are made every year and it has multiple uses. It is used to make fertilisers, animal feeds, rust removers, corrosion preventers, and even dishwasher tablets.

Some phosphate rock is also heated with coke and sand in an electric furnace to form white phosphorus which is then converted to phosphorus trichloride and phosphorous acid. And it is from these that flame retardants, insecticides, and weed-killers are made. A little is also turned into phosphorus sulfides which are used as oil additives to reduce engine wear.

Phosphate is also environmentally important. It naturally moves from soil, to rivers, to oceans, to bottom sediment. Here it accumulates until it is moved by geological uplift to dry land so the circle can start again.

During its journey, phosphate passes through many plants, microbes, and animals of various eco-systems. In addition, although all massive stars models with rotation do not always provide similar yields, they systematically overproduce C, Na and S, which are not enriched in the P-rich stars Figs.

Error bars show measurement uncertainties such as displayed in Supplementary Table 3. Another possible effect for the production of odd elements in massive stars involves advanced nucleosynthesis in convective-reactive regions and, in particular, in O—C shell mergers Although simulation of such nucleosynthesis requires expensive hydrodynamical computations, some models 28 include a prescription of such effect and provide P production factors for various masses Fig.

Depending on the amount of C ingested in the O-shell, P can be abundantly produced under these conditions together with Al, Si, Mg and O; well in line with the P-rich star chemical pattern observed. The O-C shell mergers mechanism also boosts up the production of other odd elements like K and Sc However, no P-rich star shows any significant K enhancement Fig.

However, all models produce large amounts of C and Na as in models with rotation, which again contradicts the observations.

Blue triangles and red squares are the abundances values obtained from the optical and near-IR spectra, respectively, where the arrows indicate upper limits. Error bars show the measurement uncertainties such as shown in Supplementary Table 3.

The solid black line shows the solar r-process pattern scaled to match the Ce abundance from ref. Assuming that this star is representative of all the other P-rich stars, the enhancement of the first-peak elements namely Rb, Sr, Y, Zr and the second-peak ones Ba, La, Ce, Nd together with the low Eu value seem to indicate that the nucleosynthesis in the P-rich stars is neither compatible with high-neutron density processes such as the solar-scaled r-process nor it is compatible with the weak s-process general pattern 27 , The absence of Cu and Zn enhancement further disfavors the occurrence of the weak s-process nucleosynthesis.

But even more intriguing is the really high overabundance of Ba compared to any other neutron-capture element see Methods: optical spectrum of a P-rich star. In any case, while the lack of a clear r-process pattern could rule out core-collapse supernovae 32 , other effects such as rotation may play a role and alleviate this apparent heavy element inconsistency.

Although the predictions of the massive stars models do not agree with each other Fig. Nevertheless, the same authors warned about the variable impact of explosive nucleosynthesis on the pre-explosion yields. Explosive nucleosynthesis is expected to favor the production of elements beyond Si and up to the heavy elements first peak During the explosion, Si production and the r-process nucleosynthesis are triggered; the latter favoring the production of more neutron-capture elements.

However, the P-rich stars do seem to not show any Ca, Ti or Fe-peak elements Co, Ni, Cu or Zn enhancement that is also expected by explosive nucleosynthesis. Therefore, if the P-rich stars progenitor was a massive star, the explosion yields have been reduced such as it is for the most massive models with strong fallback e.

Another hypothesis to account for the production of the heavy elements beyond the Fe-peak, considers the nucleosynthesis in compact objects, and in particular neutron stars mergers In theory, the dynamical ejecta in such objects are extremely rich in neutrons, thus favoring the production of the heaviest nuclei; i.

Similarly, models of magnetorotationally driven supernovae 34 are also able to produce large amounts of second and third peak r-process elements. However, they are actually discarded because of clear mismatches between the model predictions and the abundances of P-rich stars, among other caveats see Methods: Exotic nucleosynthesis.

In summary, although there are some promising scenarios, none of the current theoretical predictions for standard stellar nucleosynthesis can consistently reproduce all the chemical abundances in P-rich stars. Hence, the discovery of P-rich stars demands a broader exploration of stellar nucleosynthesis networks within specific conditions such as rotation or convective-reactive events.

Still, until the true nature of the P-rich stars polluters is revealed, we can speculate that they could have appreciably contributed to the Galactic chemical evolution and de facto to the Solar System and Earth.

Given the lack of any binary evidence, the existence of P-rich stars can be considered as another inhomogeneity signature Fig. Interestingly, inhomogeneities at such high metallicities have never been observed until now, suggesting that either the mixing scale of the P-rich progenitors is not large in order to overcome the already enriched interstellar medium or that we only observe the most enhanced P-rich stars, the remaining being too diluted to be chemically distinguishable.

Indeed, the mean Galactic chemical evolution of several elements — including neutron-capture elements — has been satisfactorily reproduced by adopting an empirical distribution of rotation in massive stars 7.

This demonstrates that even a minority population such as the P-rich stars population could appreciably contribute to the global chemical enrichment.

It is to be noted here that, along with a too low P solar abundance, some chemical evolution models 7 coincidentally underpredict Mg, Al and some Si isotopes in the Early Solar System. The red stars and black diamonds show the P-rich and P-normal stars, respectively, while the black crosses correspond to the optical literature values for field dwarf stars Error bars indicate our measurement uncertainties such as displayed in Supplementary Tables 3 and 4.

By combining the arguments above on the chemical evolution and the chemical patterns by stellar nucleosynthesis, we could tentatively suggest that a combination of specific effects i. However, before validating such scenario, there still remain strong contradictions between the nucleosynthesis models available and the chemical abundance pattern observed in P-rich stars. In our view, the recurrent discrepancy between the observations and all the models reside in finding a source or nucleosynthesis processes that allow strong P production but also O, Mg, Al, Si and Ce but with none or negligible C and Na enhancement.

All the data have been reduced in a homogeneous manner 40 and publicly available. In principle, the data are also analyzed via an automatic tool 41 , thus providing effective temperatures T eff , surface gravities log g and elemental abundances for each stellar spectrum. However, given that this pipeline is based on a pre-computed synthetic grid of model spectra, elemental abundances beyond the grid ranges such as observed in the P-rich stars are not valid.

The algorithm extracts the peaks in the wavelengths of interest here the strongest and less blended P I lines at For each P line of interest, a window for local analysis is created. First, the code looks for peaks of absorption or emission close to the wavelength of each P line, establishing a threshold calculated from the signal continuum and the variance, so that the algorithm is sensitive to spectra with noise or very ripple.

The detection of a P line is considered positive when both steps are met. It is to be noted here that our detection method is rather restrictive and there are probably much more P-enhanced stars to be found. For the same reason we cannot presently know whether the relatively narrow metallicity range of the P-rich stars is real or as a result of a selection bias of our detection algorithm.

Once the P-detected stars were identified, the effective temperatures were derived using a J-K-T eff relation 42 , and surface gravities log g were determined by isochrones The oscillator strengths log gf for the two main P I lines at 1.

They were checked to reproduce satisfactorily the P I spectral lines in the Sun with an assumed solar abundance of 5. The illustration of the best fits around the P lines in the P-rich stars is shown in Figs. We note that the 1. Moreover, we could also derive P abundance in a few of the best spectra of P-normal stars Fig.

We also must emphasize that the N abundances are measured via the CN molecular lines and thus are strongly dependent on the O and C abundances because of molecular equilibrium. Consequently, the N abundances displayed in Supplementary Tables 3 and 4 with only upper limits on O may be overestimated.

The systematic errors on abundances were derived by assuming the effective temperatures and surface gravities as provided by the APOGEE automatic pipeline The good agreement between the photometric and spectroscopic temperatures as shown in Supplementary Tables 1 and 2 suggests that our parameters determination is fairly robust. Random errors on abundances were evaluated by the line-by-line abundance dispersion. We rigorously applied the same methodology for the stellar parameters and chemical abundances determination to the P-normal twin stars.

The stellar parameters and abundances of the P-rich and P-normal stars and all related errors are shown in Supplementary Tables 1, 3 and 2, 4 , respectively. The chemical abundance pattern of the P-normal stars is similar to field Galactic thick disk and halo stars, as expected. The agreement between the P-normal stars and literature is overall good although some slight systematics may appear for Si, Ni or Al.

While those systematics can easily be attributed to various assumptions in both our analysis and in the literature e. The spectra were obtained with the FIES spectrograph 49 at the 2. The final abundances are shown in Fig. The latter discrepancies can be explained by the strong non-local thermodynamic equilibrium NLTE effects that, respectively, affect the Al lines in the H-band 40 and the K lines in the optical Thus, the Al optical abundance is certainly the most accurate, while for K it is the near-infrared one.

The high overabundance of Ba compared to any other neutron-capture element deserves some attention here. The high Ba content that we find is not likely a saturation effect, as this would tend to underestimate the Ba abundance rather than overestimate it. Moreover, our measurement method consists in looking only at the line wings and not the equivalent widths; the line core is much more sensitive to both saturation and NLTE.

Unfortunately, this cannot represent a constraining limit regarding the initial Li of the progenitor because the observed star, according to its stellar parameters, is very likely a red clump star, where any pristine Li has been altered in situ and even possibly fully destroyed. Reddening corrections were applied to all filters assuming reddening values provided by Bayler-Jones et al.

The synthetic spectra displayed in this figure have been tailored with the final stellar parameters and abundances using the same model atmosphere code MARCS 46 and the radiative transfer code Turbospectrum 47 as for the chemical abundance analysis see above. The luminosities reported in Supplementary Tables 1 and 2 were derived by combining distances from the Gaia mission 56 for distances less than 2 kpc and from Bayesian inference 55 and bolometric corrections The Gaia parallaxes were corrected by - 0.

While Mg is not reliable in the P-rich stars because it has been clearly spoiled by an unidentified progenitor, the Ca seems to indicate that the P-rich stars belong to the original Galactic population and has not been accreted from an external population.

The published model yields were not computed with the exact same initial composition metals as it was at the epoch of the formation of the P-rich stars and usually assume a simple solar scaled pattern.

Consequently, in order to mimic the real initial abundances of P-rich stars we added up the observed abundance pattern of the P-normal twin stars to the theoretical yields. We also stress that we use the pure theoretical yields in the comparison and we have neglected here any dilution e. However, this dilution factor would only tend to shrink down all the chemical abundance pattern together and it would thus not affect our discussion, mainly based on the relative elemental abundances.

For each progenitor type, we also display several models that reflect the variety of parameters that can influence the final yields. In particular, we show in the case of AGBs and supernovae SNe how the initial mass affects the final abundances. In the case of super-AGBs, we show also that the metallicity has a strong impact. For novae, on the other hand, we show that the white dwarf type CO or ONe has a strong effect.

Naturally, other model prescriptions can influence the final theoretical yields such as the mass loss treatment e. The variations in the model prescriptions lead to an even broader spectrum of nucleosynthesis models and stellar evolution codes in the literature.

However, a detailed review of all of them is out of the scope of this paper. Instead, we base our main argumentation on the fundamental nuclear reactions nearly independent of the model prescriptions within each stellar type e.

Nevertheless, we must note here that all the stellar abundances are bound to the quality of the nuclear reaction rates network used in the nucleosynthesis models. In parallel, it is very important that the analysis of the observations are equally accurate. Although we acknowledge that 3D and NLTE effects 66 need to be accounted for in order to certify that the analysis of the spectra are accurate, our differential approach against P-normal stars demonstrates the peculiarity of the P-rich stars pattern.

The friction of the match against the red phosphorous transforms a little bit of the red phosphorus into white phosphorus, providing the ignition needed to light the match, according to Michigan State University's Science Theater. Red phosphorus is made by heating white phosphorus under controlled conditions. In certain combinations, though, red phosphorus is still very dangerous. When exposed to enough heat F or C , it will ignite.

It explodes when combined with other compounds such as chlorine, sodium and ammonium nitrate, according to California's Office of Environmental Health Hazard Assessment , which flags red phosphorus as one of the dangerous ingredients used in making methamphetamines. The non-illicit uses of phosphorus include steel-making and the production of flares. The most common use, however, is in fertilizers, according to the RSC.

Despite its fiery properties, phosphorus is crucial to life. As phosphate, a charged molecule, it combines with sugar to form the backbone of DNA. It's also part of adenosine triphosphate, or ATP, the molecule that stores and releases energy to allow cells to function. Human phosphorus use has created problems for wildlife and people, alike.