Elements necessary for humans

At present there are 118 elements listed in the periodic table. Some of these elements are commonly found on the earth in the form of ores. Some are radioactive and have very short half lives. Many such elements have been synthesized in the laboratory and live for a very short time.

Human body like other things existing is made of compounds which are made from the elements. Out of these 118 only some elements are connected with the human body.

Although elements as such don’t make up the body it is the combined form that is molecules constitute the human body. But elemental composition is as follows by mass.

Oxygen: 65%

Carbon: 18%

Hydrogen: 10%

Nitrogen: 3%

Other elements: 4%

Other elements include Calcium, Potassium, Phosphorus, Sulphur, Sodium, Chlorine, Magnesium, Boron, Chromium, Cobalt, Copper,  Fluorine, Iodine, Iron, Manganese, Molybdenum, Selenium, Silicon, Tin, Vanadium and Zinc.

Although these elements are used in very minor amount, they are crucial to some body processes.

Elements can be divided into different groups according to the functions they perform.

Building Blocks

The main building blocks of the body are proteins which are synthesized from amino acids. For these elements used are Hydrogen, Carbon, Nitrogen, Oxygen, Phosphorus and Sulphur. DNA also contains these elements except Sulphur. DNA is the genetic code.


Enzymes are chemicals which are catalysts for carrying out chemical reactions like breakdown of sugars and other macro molecules. Such enzymes use some elements like Magnesium, Manganese, Copper, Zinc, Selenium and Molybdenum. Enzymes play role in respiration, digestion, metabolism and immune system.

Nerves and Control

Brain sends messages to different parts of the body and this is a two way communication. Electrical signals are carried through electrolytic solutions like brines. Sodium, Potassium and Calcium ions this play the role of transmitting the signals. Similarly Chloride ions regulate the water in and out of cells. Iodine is used to make hormones which regulate metabolism.

Bones and Teeth

Bones make the template on which our body is hoisted. Strong bones and teeth are essential for the healthy body.  Bones and Teeth are made of Calcium and phosphate. Phosphate contains Phosphorus and Oxygen. Manganese element makes more stronger and resistance to breaking.


Blood is the lifeline of the body. Blood carries oxygen to the cells and removes the carbon-dioxide gas which is the byproduct of combustion reaction. Oxygen is carried by blood due to the presence of iron which binds the Oxygen. Other elements which are constituents of blood are Carbon, Oxygen, Iron and Cobalt. Cobalt is essential to make red blood cells.

Respiration and Energy

Respiration is inhalation of Oxygen. Adinosine Triphosphate (ATP) is formed during respiration which is the compound used by body as energy. Main elements involved here are Carbon, Nitrogen, Phosphorus and Oxygen.

Source: c&en magazine of American Chemical Society (ACS)


Achievements of a wandering mind

Many a times you must have experienced in your life that you cannot recall a certain incident, name of a person or a book or author although at other times you remembered it so well. In those circumstances, the harder you try to recall more it eludes you. It is not the case of poor memory or age as it happens with everyone at one time or another. You leave it frustrated and become busy in some other work and in a flash the things will come to your mind. The same has happened to many great scientists and authors.

August Kekulé von Stradonitz, the great chemist who elucidated the structure of benzene did it in reverie while riding a horse drawn bus. As he will doze off, he saw the atoms dancing before his eyes. These atoms caught hold of each other. The bigger ones held more than one smaller atoms and so on. Thus he was able to arrive at the ring structure of the benzene molecule. Not only that, he was able to draw the structure of molecules with same molecular formula but different physical properties. He was talking about geometrical isomers. It was left to his brilliant young student Vant Hoff to discover the sterochemistry of carbon molecules in which for different groups are attached to a carbon atom. Such carbon atoms are said to be asymmetric and stereo isomerism imparts a property of deflecting light to right or left from its path when light travels through the solution of such substances. Such molecules are called optically active compounds with dextro (right) rotatory and levo (left) rotatory categories. Whenever such compounds are synthesized in the laboratory we end up with 50:50 mixtures of both forms which are optically inactive because the deflection caused by one set to left is countered by another set to the right. To separate these mixture into pure forms, these mixtures are reacted with a pure levo or dextro rotatory compound resulting in two salts of different melting of boiling points which are easily separable. After separation the add on moelcule has to be detached to obtain the pure compound of levo or dextro nature. n nature, we encountered only single type of compounds either levo-rotatory or dextro rotatory because most of the natural compounds are synthesized by different routes using the enzymes. It was the great Luis Pasteur who separated the two optically active  forms of tartaric acid crystals using tweezers and demonstrated the optical activity. The weather of France also assisted him because the tartaric acid obtained from the raw grapes formed large beautiful crystals.

Another example of great achievements of wandering mind is that of Greek mathematician Archimedes. He was given the commission by the King to know whether the crown he ordered to be made was really of Gold or of gold alloy. Archimedes thought and thought about solving the problem from many angles but was frustrated and he decided to leave aside the problem for sometimes. He ordered his servant to make a bath for  him. As he lowered himself into the bath, he saw the level of water rising. The idea that same weights of different elements displace the different volume of water suddenly flashed to his mind. This way he can find the volume that a certain weight of gold will occupy perhaps by comparing the crown weight by same weight pure gold. He was so elated that he jumped out of the bath and ran naked towards the palace shouting the now famous word  “Eureka”