phosphorus can make more than the normal possible bonds because of excitation of electrons. Does this happen only with phosphorus or also with other elemnts of period 3 ??

In 1669 the Hamburg merchant and alchemist Hennig Brandt heated the residue from evaporating urine with powdered charcoal, and condensed the vapor that was evolved into a waxy solid. This solid glowed in the dark, without heat, an astonishing phenomenon. He called the mysterious substance phosphorus, taken directly from the Greek phosphoros, "light-bringer." This was also the name of the planet Venus as morning star, "Lucifer" in Latin. The discovery created quite a stir, and soon nobody was throwing away urine. Travelling alchemists amazed royal audiences, and it was the talk of the time. A normal person excretes about a gram of phosphorus daily.

It gave the name to phosphorescence, which is the nonthermal emission of light after the stimulus has been removed, in distinction to fluorescence. The light Brandt observed was chemiluminescence, consequent to the combination of the phosphorus with atmospheric oxygen to form the trioxide. This was burning, but the light is not due to thermal excitation. When the pentoxide is formed, there is no chemiluminescence.

Phosphorus is an important agricultural fertilizer, an essential element in metabolism and the transfer of biological energy, a component of matches, an ingredient in pyrotechnic applications, and besides of considerable scientific interest. Some of the properties, applications and lore of phosphorus are reviewed in this article. Phosphorus presents many puzzles that are unsolved or only partially solved, which will make this discussion more interesting.