What Is Phosphorous: The Element
What is Phosphorous? Phosphorous is the 15th element in the Periodic Table. The nucleus of a Phosphorous atom contains 15 protons. Phosphorous is very reactive and is never found in pure form in nature. It is capable of forming both ionic and covalent bonds with other elements, and the type of bond is determined by the electronegativity of the element being bonded to. Phosphorous is an important ingredient in DNA and many other living processes. It is also used heavily in fertilizers such as phosphate and super phosphate, which we have come to rely heavily on for food production. Phosphorous is also important in the solar panel industry as a dopant of Silicon which is part of the process of electricity generation in the solar energy cell. What Is Phosphorous: Isotopes
There is only one stable version or isotope of Phosphorous, which is 31-Phosphorous which is shown in the Bohr diagram to the right. This type contains 15 protons and 16 neutrons in the nucleus of the atom and accounts for all the naturally occurring Phosphorous found on Earth. Other isotopes can be prepared by exposing Phosphorous or other appropriate elements to different kinds of radiation, but these all have very short lives. 32-Phosphorous is one radioactive isotope that is used as a chemical marker in laboratory experiments. It has a half life of approximately 14 days.What Is Phosphorous: Electron Structure 
The 15 electrons of Phosphorous are arranged into three shells, with the overall electron details of 1s2 2s2 2p6 3s2 3p3 which results in 5 outer shell electrons and hence the electron dot diagram shown to the left. We can immediately see from this diagram that it has the same outer shell electron structure as Nitrogen, which is why Phosphorous is placed in the same column of the Periodic Table as Nitrogen.Like Nitrogen, Phosphorous requires an additional 3 electrons to achieve the stable condition of 8 electrons in its outer shell. This means it can either pick up three free electrons, if there are any available, to form the negatively charged Phosphorous ion P3-, or it can share three electrons with other atoms to form compounds.
What Is Phosphorous: Structural Forms Phosphorous is an element that can occur in several different pure forms, called allotropes. The best known of these are white and red Phosphorous. These two forms contain only Phosphorous atoms bonded to each other.
White Phosphorous This consists of four Phosphorous atoms bonded to each other in a 3 dimensional pyramid shape, as shown to the right. You can see that each atom is bonded to three other atoms, thus meeting the requirement of 8 electrons in the outer shell. This is a very unstable structure and will rapidly react with Oxygen to form Phosphorous Pentoxide, P2O5. As it reacts it gives off a great deal of heat and also light.These properties make it useful for military applications such as flares, smoke generators and assorted anti-personnel weapons. Phosphorous burns can be horrific and can have additional effects such as poisoning from the P2O5 gas generated from the Phosphorous burning and cardiac arrest from depletion of Calcium from the body. Red Phosphorous This is a slightly more stable form of pure Phosphorous. It is comprised of Phosphorous atoms bonding to three others, as in the white form, but the bonding is not as clear cut. There are many variants of the bonding, from amorphous (no distinct form) to definite lattice. The image shown below shows how a lattice can be built from Phosphorous atoms bonding to three others. Note that in reality this structure would not be flat, but would be 3 dimensional and would follow the Valence Shell Electron Pair Repulsion, or VSEPR, theory.
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