[Chemistry Class Notes] on Properties and Reactions of Phosphorus Pdf for Exam

Phosphorus hailing from the family of nitrogen is a non-metallic chemical. This chemical is pale, transparent, semi-transparent, odourless, and tasteless in nature. It is not available freely in nature in any form. Being the 15th element in the periodic table, phosphorus emits flumes when put in contact with air. It is stored in water in most chemical laboratories to avoid catching fumes or fire. 

The occurrence of phosphorus in the crust of the earth is about 0.12% and occurs as phosphate. The United States, the largest producer of phosphorus, mined 13,300,000 metric tons in the year 1996. Bone ash and urine were the first primary sources of phosphorus. 

Discovery of Phosphorus

The discovery of phosphorus dates back to 1669 by Hennig Brand. Strongly believing that urine had the capacity to transform lead into gold paved the way to the discovery of this non-metallic chemical. Further, he started heating and purifying about 60 buckets of urine just to find out the magical element that could turn into gold. It was exactly then he discovered ‘Phosphorus’. 

Properties

There are three allotropic forms of phosphorus – they are pale or white phosphorus, red and black phosphorus.  The phosphorus chemical element properties and reactions vary as per these forms.

• Red Phosphorus – Red phosphorus is commonly seen on one side of the matchstick. The red phosphorus is formed as a result of heating white phosphorus at 250 degrees celsius. It does not dissolve in liquids. 

• Black Phosphorous – The black one is obtained by heating white phosphorus in really high pressure. 

• Black Phosphorous – The black one is obtained by heating white phosphorus in really high pressure. It resembles graphite. 

Phosphorus is classified into group 15 of the periodic table. It is solid as per the physical state. 

Medical Uses of Phosphorus

Phosphorus-32 is the radioactive isotope. Its uses are varied. It is used in various medical treatments such as the polycythaemia vera. It helps detect tumours in various parts of the body, such as the brain, breasts, etc. The radiations of radioactive isotope phosphorus-32 treat cancer. 

Reactions

The shell arrangement of phosphorus is like the arrangement of nitrogen. The 3 half orbits form a single covalent bond. When combined with various elements, phosphorus shows oxidation. Phosphorus is said to have larger atoms and low electronegativity which influences its properties and reactions. Unlike nitrogen, phosphorus allows the expansion of octet, which leads to the formation of 5 covalent bonds in compounds. 

Biological Aspects of Phosphorous

Phosphorus is found as phosphate in the body. Phosphate is found in the DNA and RNA of the human body. Phosphorus is an active part of the distribution of energy throughout the human body. 

The recommended dietary intake of phosphate is 800 mg per day. Some of the foods that are rich in phosphorus are turkey, chicken, tuna, eggs, salmon, cheese etc. Consumption of phosphate in larger quantities than that which is required leads to serious health issues like osteoporosis, kidney problems etc. Exposure to white phosphorus sometimes leads to drowsiness, nausea, stomach pain etc., in some people. 

Applications of Phosphorus in Industrial Use

Phosphorus is utilized in the production of steel, in the manufacture of fertilisers, improving the quality of the crop or soil. It can yield phosphine and phosphorus oxyacids which are used in commercial pest control. They are used as smoke screens, incendiary fire or bombs in the field of the military. Other industrial uses of phosphorus are – 

1. Flame retardant

2. Aid in processing 

3. Metal alloy constituent 

4. Intermediates 

5. agricultural chemicals 

6. Material recovery

7. Plastic production 

8. Fabricated metal product manufacturing 

9. Resin manufacture 

10. Organic chemical manufacture etc. 

Variable Oxidation State 

The variable oxidation state of phosphorus goes from -3 to +5. 

Sample Questions and Answers

1. What are the Properties and Uses of Red Phosphorus? 

Ans: Red phosphorus is derived by heating the white phosphorus. It is stable when compared to white phosphorus. Its melting point is at 860K. 

There are many uses of red phosphorus – used in matchsticks, production of pesticides, organic synthesis, production of smoke bombs, water softening, electroluminescent coating, etc. 

2. Who Discovered Red Phosphorus? 

Ans: Red phosphorus was discovered by an Australian chemist named Anton von Schrotter. He discovered it in the process of heating white phosphorus at 482 degrees celsius in the presence of nitrogen. 

3. Is Phosphorus Present in the Human Body? 

Ans: Yes, phosphorus is present in the human body. It is found in the liver, kidney tissues, brain, blood, saliva, urine.