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)

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1905: Annus Mirabilis of Albert Einstein 

Annus mirabilis is a Latin phrase that means “wonderful year”, “miraculous year” or “amazing year”. This term was originally used to refer to the year 1666, and today is used to refer to several years during which events of major importance are remembered.

Albert Einstein singlehandedly added 1905 as another Annus Mirabilis. In this year, his creativity peaked and he made the revolutionary scientific discoveries. He was just 26 years old. During that year he did:

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March: Proved that the light consists of photons thus proving the quantum nature of the light.

May: Proved the existence of the atom.

June: Special Theory of Relativity, which forced the laws of motion by another great physicist Newton as the corollary with the objects moving at lower speeds.

November: The most conscise and beautiful equation relating mass and energy. Proving that mass and energy are two names of the same thing. That enormous amounts of energy are condensed to make small amounts of mass. In other words, enormous amounts of energy are contained in the mass.

E=mc2

And after that he became a superstar

}

Concept of pH in Chemistry

Although the pH of a lake or polluted stream is seldom reported in the media, the people who are monitoring the health of the lake water record it daily religiously. But pH is quite an important physical property of water. pH of a stream gives an indication about the salts and other soluble matter present in the water. These soluble salts affect the organisms living in the water. Also changing pH in a stream can be an indicator of increasing pollution or some other environmental factor.

As we know life on our planet is based on the water. Water is a unique solvent as it dissolves a number of chemicals in it. Water molecule is a simple one with H2O as its formula indicating 2 hydrogen atoms joined to 1 oxygen atom. It V shaped geometry imparts it high polarity with which it is able to break down many salt molecules into individual ions called cations and anions. As such water is slightly ionized into equivalent amounts of hydrogen and hydroxyl ions. The value is 10-07 equivalents, a very very tiny value indeed. But this small value is enough to do all the chemistry. When chemicals dissolve in it, the values of hydrogen and hydroxyl ions become unequal. Particularly when any compound containing hydrogen ions is added to water, hydrogen ions become predominant and solution is said to become acidic and such chemicals are called acids. Examples of acids are hydrochloric acid, nitric acid, citric acid and sulphuric acid. On the other hand, when any chemical which have hydroxyl ions is added to water, hydroxyl ions predominate and water becomes basic and such chemicals are called bases.  Examples of bases are sodium hydroxide, washing soda and potassium hydroxide.

pH is a measure of how acidic/basic water is. It is defined as the minus logarithm of hydrogen ions concentration. Since -log[10-07] is 7, the pH of pure water is 7. The range goes from 0-14. Any solution having pH value less than 7 is acidic and above 7 is basic in nature.

The pH of any natural water determines availability of nutrients like phosphorus, nitrogen, and carbon for aquatic life. Many nutrients like phosphorous are very sensitive to pH since it exists in different forms at different pH values. Only a particualr form is assimilated by the organism.

Similarly, pH determines the solubility of heavy metals which are generally toxic in nature. Heavy metals are generally more soluble at lower pH and hence lower pH gives a warning about the possibility of these heavier and poisonous metals.

pH of Battery acid is 1, vinegar is about 3, milk slightly above 6, baking soda between 8 and 9 & ammonia solution about 12.Diagram of pH. pH 1=battery acid, 2=lemon juice, 3-vinegar, 6.5=milk, 8.5=baking soda, sea water, 10.5=Milk of Magnesia, 12=ammonia, 13=lye. ph 3 to 4=Adult fish die. ph 4-5=Fish reproductionaffected. pH 5-6.5=Normal range for precipitat on. pH 6-8=Normal range of stream pH. pH 1-5=Acid rain.

Is there life on Mars? Again Microbes hold the key

Earliest life of single cell evolved into 3 branches having distinct traits. The branches further subdivide into more branches on the evolutionary tree of life called Phylogenetic tree of life. The first three branches are called Bacteria, archaea and Eucaryota.

450px-Phylogenetic_tree

As we can see in this tree, there is a member of archaea family with the name Methanogen. This microbe holds the answer for presence of vast quantities of methane which is trapped inside the ice cages called methane hydrates. These hydrates are found on Earth in the permafrost regions having very low temperatures or under the deep sea floor. Water molecules arrange themselves into octahedral cubes in which molecules of many compounds can fit into them. These are called clathrate compounds. These structures are very fragile and as soon as the overhead pressure is reduced or temperature increases, the structure crumbles and gas is released. So special technology is required to produce the methane from hydrates. In US, carbon dioxide was pumped into the hydrate layer. It substituted into the cages releasing the methane free. It served two important purposes. First the production of fuel gas methane and sequestration of unwanted carbon dioxide. These microbes use carbon dioxide and hydrogen to make their food and also generate methane and water. These microbes are very enterprising. They can use alternative sources of carbon like acetates which are the products formed by another kind of bacteria by breaking the macro-molecules present in the buried organic matter, for their food. One thing these tiny beings hate is oxygen. They work in anaerobic environments like deep buried locations.

Now this microbe is being held responsible for the methane gas found on Mars indicating that there is life on the planet. It means Mars is not a dead planet. Professor James Kasting said if there is anything alive on Mars at this time in its history, it would probably be some form of microbial life living deep beneath the planet’s surface. Perhaps the most likely form of microbial life is a type of bacteria known as methanogenic bacteria, or methanogens for short. The CO2 needed by the methanogens could presumably come from the atmosphere. The H2 could come from chemical reactions between water and certain types of rocks, specifically magnesium- and iron-rich basalts. Such rocks are found on certain parts of the seafloor today on Earth. When they react with water, they form minerals called serpentine minerals. In the process, hydrogen is produced. The reaction that produces methane is thermodynamically favorable, so Methanogens could use the energy released by this reaction to drive their metabolism. Microbes can make many reactions happen at much lower temperature by changing the path of reactions through enzyme catalysts which these microbes synthesize.

Simply Mind Boggling

Scientists speculate that all the fundamental particles were created from the energy immediately after the Big Bang event in which Universe was formed. Then these atoms combined in different permutations and combinations and molecules were born. Context of immediately in the cosmic events is not similar to the usual terms with which define our world. It may be millions of years.

Earth was formed but its climate was not like the present day. There was no life except one algae namely “Blue Algae” known in the scientific language as “Cyanobacteria” where “Cyano” stands for blue color. It thrived in the water which occupied 70% surface of the Earth. All around in the atmosphere was carbondioxide and metals existed in the solution form because there was no oxygen to react with them and precipitate them as ores. Iron was the most abundant of them. So this was the scene about 3.5 billions of years ago.

How did these small living beings sustain themselves? Where from did they get the energy? .

They developed the photosynthesis and harvested the energy of Sun. They also did much of the chemistry which resulted in critically changing the composition of gases in the atmosphere. They learned to break the water molecules into hydrogen and oxygen. They then used the hydrogen along with carbon dioxide to make carbohydrates which are the store house of energy. The oxygen gas which was generated was very reactive and reacted with the metal ions especially iron species and got fixed up and ores were formed. This went on for millions of years. Iron acted as a perfect sink for oxygen which was poison for these bacteria themselves because they thrived in the anaerobic conditions.

But a stage reached when no more free iron ions were available. So the concentration of oxygen began building up in the atmosphere and setting a stage in which the new species of life which use oxygen for breathing to evolve. The life started in the real earnest. The oxygen content stabilized at about 20% by volume in the air. Carbon dioxide has very small percentage. So these humble microbes were responsible for the life as we see today on this Earth.

The algae learned to live with the existing conditions.

How big is the cyanobacteria? It has been estimated that its diameter is about 2 microns if we consider it as a sphere which it is not. But for the sake of simplicity and bring home the point as is done in all the scientific inquiry let us assume that. Such a small size !! But is it really small in comparison to the smaller things nature can go to. Let us compare it to the size of carbon atom. If we calculate the volume of bacteria and volume of carbon atom, and calculate how many atoms of carbon can fit into the bacteria, you shall be surprised that a mind boggling 1000000000000 atoms is the answer. You are in for more surprise if you go down to fundamental particles like electrons and leptons.

So this is the scale at which the machinery of the Nature works. On one side are the atomic sized particles and on the other are gigantic stars. But one thing is sure that at the base of everything are the fundamental particles. It is also a fact that things behave very differently on the different scale levels. Electrons can behave as particles under one set of conditions and as a wave in the diffraction experiments. Or they may be behaving as they are but with our existing knowledge  we try to explain the things the way which give reasonable answers.

So let us salute to the “Cyanobacteria” to create favorable conditions for the existing worlds to forms and initiation of the diverse kinds of species on this Earth.

Chemistry by Nature

Nature is a great chemist. It synthesizes millions of compounds every moment ranging from simple molecules like methane to very complex molecules like carbohydrates, cellulose and proteins. Most of these compounds are synthesized by plants. From the plants they are passed on to animals because the animals cannot synthesize their food by themselves. But there are many chemical reactions occurring inside the cells like breaking down the complex molecules and unlocking the energy which is stored in them.

Where does all the energy locked inside the different molecules come from? Most of it is derived from the Sun light. In many cultures like Hindus and Egyptians, Sun is worshiped as the harbinger of life. They may not be knowing the scientific facts behind it. Energy tries to dissipate and some storage is required to held it at one place and use it whenever required. Cells are the prime example.

How do the plants get hold of the energy. They carry out a reaction called photosynthesis in which they combine carbon dioxide and water in the presence of sunlight. All this work is done with the help of a big organic molecule called Chlorophyll. The products of this reaction are sugar and oxygen. When human beings consume the sugar, they break it down again to carbon dioxide and water and energy absorbed from the sun is unlocked and nourishes our bodies.

This reaction is a fuel burning reaction. But unlike the burning of fuels it happens at a very low temperature (body temperature) in our bodies although both reactions are exothermic in nature. How is this achieved? First of all, only those reactions are possible which results in products having lower energy than the reactants. But to initiate the reaction, the system has to cross a energy hill called energy of activation.

Catalysts are capable of making the reactions occur at low temperatures because they lower the energy of activation. In our bodies there are specialized proteins which are called enzymes which act as catalysts. These are very specific and one enzyme is specialized for only one task.

Catalysts also determine the kind of product that is synthesized. For example, the hydrogenation of unsaturated oils can be carried out by reaction with hydrogen. In the case of using a catalyst, only cis addition to the double bond is allowed whereas without catalyst in addition to elevated temperature and pressure conditions, the product formed is a mixture of both cis and trans products.

Since in the nature most of the reactions are carried out at ambient conditions, enzymes are generally utilized by the nature. In the case of molecules having asymmetric carbon centres a mixture of 50:50 ratio is produced without enzymes. These are called stereo-isomers and rotate the light in left and right direction. But in nature only one of these forms is synthesized. After all animals consume only one form of stereoisomers.

So nature is a great chemist.

By any means tenable or Untenable

Thermodynamics is the most important branch of the science dealing with the energy, work and conversions of one form of energy into other forms. It cuts across many branches of the courses like physics, chemistry and engineering. All the students in these streams have to come face to face with this subject.

Its laws have become so perfect that they can be bound into mathematical equations. First law of thermodynamics is concerning the conservation of energy.  Suppose there are two systems which are having energies A & B. If they are connected, then the energy of the resultant system shall be A+B.

But there is a catch. This law does not impose any restrictions on the donors and recipients of the energy. For example, we can heat the water by extracting (suppose we are having such an extracting machine) heat from the ice. After all the total has to remain constant and sum of the energies of two systems. But the common experience is contrary to this. Heat always flow from higher temperature to lower temperature.

To address this difficulty, second law of thermodynamics was proposed. This takes into account the natural phenomena. Another thermodynamic function called “Entropy” was formulated. This is the measure of randomness of the system. All the systems in nature tends towards chaos or randomness.