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

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

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)

Changes in Periodic Table of Chemicals….

We know that everything in the universe is made from the atoms. They are the basic building entities. Atoms are not solid entities but are made of dense nuclei surrounded by fuzzy cloud of electrons whizzing in the outer. Nucleus is made of protons and neutrons. Things don’t not end here. Nature is very complex. Even the atoms of same elements can have different number of neutrons making them have different weights. Such atoms are called isotopes. Atoms of same element or different elements can combine in umpteen ways resulting in diverse molecules and different substances from very simple molecules like water and methane to complex molecules containing thousands of atoms.
Many elements have more than one isotopes. One of these is the most abundant and is for all practical purposes considered as the representative. Other isotopes exist in very low abundance. All elements can be divided into different groups in which the chemical and physical properties vary in periodic manner.
Earlier, we remember the chemical composition of compounds was determined by chemical methods using classical techniques. From the elements proportions an empirical formula was derived. Methods gave numbers of constituent elements which have to be rounded off.this happened due to the inherent limitations of determinations. So generally the molecular weights were either whole numbers or at most rounded off to first decimal place.
Thanks to the extremely accurate measurements now available with advancement of science, we are measure the abundance of all isotopes very accurately. Ten elements namely hydrogen, lithium, boron, carbon, nitrogen, oxygen, silicon, sulfur, chlorine and thallium which have one or more isotopes have now been selected whose atomic weights shall be displayed in the periodic table as a range. For example, the atomic weight of boron (atomic number 5) is currently written as 10.811. On the new periodic table, it will be given as an interval—from 10.806 to 10.821. This might not seem like a big change—and it is very small—but such a change can be critical to calculations in scientific research and for industrial applications. Also, chemistry teachers and students will have to learn how to use the new weight intervals.
Since now we the abundance and atomic weights of each isotope very accurately, the range will fix the upper and lower limits. By comparing the atomic weight of a particular element in a sample and mapping it on the range interval we can know the source of sample.
For example, oxygen atoms in the water samples contain isotopes. During evaporation fractionation occurs. Water molecules with lighter oxygen atoms evaporate faster leaving behind the water with heavier isotopes.
Similarly, the atomic weight of carbon is smaller in performance-enhancing drugs than in natural testosterone meaning natural testosterone contains higher abundance if heavier carbon atoms. This difference can be used to test whether athletes used these drugs to improve their performance.
The new atomic weight measurements not only account for the presence of isotopes but also consider their relative concentrations in the universe. Carbon 12 makes up 98.89% of all carbon, while carbon 13 is 1.11%, and the natural abundance of carbon 14 is 0.0000000001%. So, the weight interval for carbon will lean more heavily toward carbon 12 and range from 12.0096 to 12.0116. This range will replace the average atomic weight for carbon listed in any chemistry textbook, which is 12.011.

Exceptional Brains

Human beings are endowed with power of thinking. All this is possible due to highly evolved brain. But some of us humans are exceptional. Do they see visions? They can predict the events of future. Following are such incidences from the science field.

Sir P.A.M Dirac is considered as the greatest physicist in Britain after Newton. A stern father made him the man of few words. But this trait turned on an intense internal energy which manifested in the form of beautiful equations when he married Einstein’s relativity with quantum mechanism. On the basis of his research, he envisaged sub atomic particles which have equal and opposite electrical charge and equal mass to particles like electrons. His equations yielded two solutions like quadratic equations. Proof came soon when in a experiment in cloud chamber, a particle, hitherto, unknown was observed following mirror trajectory to the electrons emitted from a radioactive particle. It is clear that in a magnetic field, the particles follow a circular trajectory. So this particle was opposite of electron with equal mass. So his prediction was borne true. This particle is called anti-electron or positron. Soon, it became known that there is antimatter to every type of matter. In fact, now scientists believe that there exist space with antimatter and efforts are on to exploit their potential.

Another such great person was a Russian chemist. His name was Dmitri Ivanovich Mendeleev. At the time when he was on the scene, the concept of atomic number of elements was unknown. Only few elements were known to chemists. The physical parameter which was considered important for distinguishing the elements from each other was atomic weight. He was the first man to arrange the elements in groups based on their properties. His insight of the nature was so great that he left many blank places for elements which were not known then. He gave them names prefixed by eka, dvi and tri added to the element preceding the one with eka prefix. For example, ekaboron was the name of element which occupied next place to Boron. It was later discovered and is called Scandium. He had predicted all the properties of the element to be discovered and they matched almost exactly to the element when discovered. His periodic table is the forerunner of the modern periodic table which has evolved over time and is based on the atomic number concept. It is based on the premise that elements in a group have similar electronic configuration and all the elements fall in periods with elements in group having similar properties but increasing atomic numbers. Each element has an added shell of electrons to the previous one. Incidentally, prefixes eka, dvi and tri have been adapted from Sanskrit and mean one, two and three. This love for Sanskrit is said to be due to the influence from a friend who was a Sanskrit scholar.

Kekule, an organic chemist was another exception. He dreamed dreams about atoms and their arrangement. He did it another way around. To explain the unusual properties of a chemical compound and its strange molecular weight, he was so much involved in the thoughts that he was always lost in the reverie. Even while travelling in bus from his laboratory to his home he was so absorbed in the thoughts of figuring out the formula that will explain the observed properties that he had to be reminded by the conductor about the end of his journey. And one day, he saw a dream in which atoms were dancing. Then heavier of them turned into snakes which were joined to each other as each snake has the tail of other one in his mouth. He woke up and rest of night worked out the formula of the first of the aromatic compounds called Benzene.

Putting the Elements in their Proper Places

Elements are entities of the matter which have different chemical and physical properties. Almost all the elements exist in the form of compounds in which different elements are joined in definite ratios and this ratio is always constant. Water is made up of 2 atoms of hydrogen element and 1 element of oxygen. No matter from where you collect the water, it shall have the same composition.

But notwithstanding the differences, they form groups which are like the siblings. They are similar and dissimilar at the same time meaning that they follow a progression of physical and chemical properties. For example. there are elements which called alkali metals which form hydroxides having high pH solutions in water. Only difference is that pH will be different for hydroxides of different metals.

From the days of alchemy, chemists were fascinated by the elements and trying to group them in such a way that elements closer in nature to one another come in one cluster. It was also observed that by placing the elements in rows and columns, moving along a row, at the end of the row, the next element shall be like the first element of the previous row. They tried to understand why sometimes atoms of different elements have strong affinity for each other whereas other atoms hate each other and have to coerced to react with one another.

On the earth’s surface and subsurface, elements are found in the form of compounds and constitute the minerals. Sand or silica is composed of silicon and oxygen atoms and bauxite is made up from the combination of aluminum, oxygen and hydrogen atoms. The lifetime endeavor of many chemists was divide the elements in groups in such a way that properties of elements adjacent to one another can be predicted by looking at their location. They were trying to place them on the paper with their locations in definite arrangements.

After so much efforts, it was the genius of Dmitri Ivanovich Mendeleev, a 19th Century Russian chemist, who came up with arrangement of 63 elements known in his time based on the periodicity of the properties. In placed them in rows called periods and columns called groups and the periodic table of elements was born. The name periodic indicates the periodicity in the properties of the elements. In his time, the concept of atomic structure of atoms was unknown. No one knew the atomic numbers. But in the end when these concepts became popular, the foundation of the periodic table was put on a more firm bases.

Was it not for the genius of the man that he reserved the place in his table for many elements which were undiscovered yet. Despite the many skeptics, he was proved right again. He was influenced by Bohtlingk, a Sanskrit scholar of Russia who was his friend and was preparing the second edition of his book on the Panini who is known for his grammar of Sanskrit, particularly for his formulation of the 3,959 rules of Sanskrit morphology, syntax and semantics in the grammar known as Ashtadhyayi (अष्टाध्यायी Aṣṭādhyāyī, meaning “eight chapters”), the foundational text of the grammatical branch of the Vedanga, the auxiliary scholarly disciplines of Vedic religion, when he gave the prefixes eka, dvi and tri for unknown elements being 1, 2 and 3 places below known element  in the group of elements. For example “ekaboron” was 1 row below and was ultimately identified as Aluminum and so on.

Although the Periodic Table of the Elements was one of the most fruitful ideas to come out of scientific research in the 19th Century, Mendeleev was never awarded a Nobel Prize for this work, although he came within one vote of it in 1906. The reason cited is that one member of the awarding committee argued, rather eloquently, that Mendeleev’s 1869 work had already been widely accepted as a basic part of chemical knowledge, and had already been put forward by the Italian chemist, Stanislao Cannizzaro.

Dmitri Mendeleev died peacefully during a reading of Jules Verne’s Journey to the North Pole, aged 72 on 20 January, 1907. (This was six years after the Nobel Prizes were first awarded).

Since then, eight elements have been discovered and nearly 30 have been made in the laboratory. Mendeleev has the rare distinction of having an element, that with Atomic Number 101 (Mendelevium), named after him. This synthetic element was obtained by Albert Ghiorso, Glenn T Seaborg and co-workers between 1955 and 1958.