Tag: Atom

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

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Story of two charged dots

Once upon a time many years ago, there were two charged particles. They came to existence within a short span of time to one another. How do we trace their journeys in the time? Well scientists use cloud chamber to trace their paths in the space with time. This is a writer’s device so it can be extraordinary and perfect.
From their trajectories it is clear that they had opposite charges but very far apart in the beginning. But their traces were of opposite slope and thus they were heading to a collision in future. Force of attraction also began playing its part in bringing them closer and closer.
Eventually they met and neutralised their charge and became an atom. Although being one but had their independent existences also. The resultant product was stable for many years.
Then under the influence of external forces and due to a sense of ennui, the atom began to become unstable. It began to expand. Both charges began distancing from each other. Like the universe which is expanding continuously, the charged dots started loosing communication with each other and becoming more and more independent identities again as they were in the beginning. Soon they will be out of the view of cloud chamber screen. The scientist shall have to zoom out the screen to see them both moving away from one another and losing out the finer details in the process. Story will come to an end.

Optical Isomerism

Everything is identical about these twins. Number of atoms, type of atoms are same. Only difference is the spatial arrangement of atoms or groups of atoms attached to the carbon atoms. There is one more trait of these twins-they are mirror images of one another. They are called stereoisomers. Stereo means spatial.

There is a slight differences in the reactivity of these members. One very interesting property of these molecules is that they rotate the light passing through their solution in equal and opposite directions called Levo and Dextro.

When such compounds are synthesized in the laboratory, we obtain both isomers in equal amounts and there is no optical activity because effect of one type isomers is nullified by the effect in opposite direction.

But in nature, synthesis of macro-molecules like carbohydrates, lipids and oils by the biological enzyme driven reactions we exclusively obtain only one kind of isomers-mostly levo-rotatary. This is due to enzymes which are proteins and very specific catalysts whereas industrial catalysts are surface active and both isomers are manufactured in equal amounts. Special techniques are required to separate them into pure Levo or Dextro isomers. Due to this reason the cost of these isomers increases manifolds. It has been found that some diseases respond to specific isomers. Such medicine are called stereo-specific medicine.

Carbon Dating

There are atoms which have same chemical properties but different atomic weights. They have same atomic mass because number of protons are identical but additional neutrons make then different in weight. Such atoms are called isotopes.

For example carbon which has 6 protons and 6 neutrons have an isotope which have 6 protons but 8 neutrons.  They are presented as C14 and C12. Addition of protons make them less stable and many of them are radioactive. The rate at which a particular atom decays is independent of temperature, light or darkness. During decay the atom is trying to achieve state of minimum energy and produces atoms with lower atomic numbers and energy.

The rate of decay is expressed in terms of half life. For example a given weight of C14 atoms will become half in weight in 5600 years. precisely.  Then the remaining mass will again take 5600 years to become 1/4 th and so on. This property has many uses and one of the most popular one is carbon dating to determine the age of wood.

Vegetation absorbs CO2 and the same C14/C12 proportion is found in wood as in the atmosphere as long as the tree is alive.But, after a tree is felled it no longer absorbs CO2 from the atmosphere. Inside the dead wood, the C14 brothers slowly disappear, and are not replaced. So, a piece of wood from a Pharaoh’s tomb contains a far lower C14/C12 proportion than a tree that has recently been felled. This type of clock is particularly useful to archaeologists, and allows them to date wood between 200 and 20,000 years old.  The ratio of C14/C12 is measured using a ratio recording mass spectrometer.

A Soccer Ball and C60 Molecule

Carbon, a small atom with atomic weight of 12 amu and atomic number of 6, is the element on which the life on this planet is based. Carbon atom forms 4 single electron bonds of sp3 configuration and hence can combine with 4 different atoms including carbon atoms. Thus it can form giant or macromolecules often found in nature. Some examples are carbohydrates, hydrocarbons, proteins, lipids and so on.

Buckminster Fuller

Carbon as such exists in two allotropic forms namely diamond and graphite with very different physical properties. While diamond is the hardest material and inert towards chemicals, graphite is active, chemically not inert and conducts electricity with ease and has a structure made of hexagonal sheets separated by electron clouds. There sheets can slip over each other making graphite a lubricant. Scientists has been able to separate these 1 atom thick sheets which have extraordinary properties like many times stronger than steel, easily foldable and superconductor of electricity. These sheets has been named Graphene.

Possibilities do not end here. In the interstellar dust, giant molecules of carbon which are very stable and inert have been detected. One of them is C60 molecule. If it was to be superstable and chemically inert, it should have a closed structure. Smalley and Kroto who were awarded Nobel Prize for the discovery looked towards the domes constructed by Buckminster Fuller outlined above. They called this molecule Buckminsterfullerene in his honor. A soccer ball is known as truncated icosahedron which has 60 vertices, 32 faces: 12 of which are pentagonal and 20 hexagonal. Famous architect Buckminster Fuller constructed biosphere structures which are very stable and energy efficient because a sphere has maximum volume but minimum surface area.

Graphene: Size Zero Allotrope

Carbon is the atom on which the life on the earth is based. Though it is not a complicated element having only 6 atomic number, it ability to form compounds with hydrogen, oxygen, sulfur and host of other atoms and its ability for catenation makes it the most distinguished element for us. We owe our existence to it. Most of the macromolecules which are bodies are composed of contain carbon, hydrogen and oxygen.

This simple element show another very surprising properties. One of them is the allotropy. Two allotrope are two different arrangements in which an element can exist. Till 2004, two allotropes of carbon, diamond and graphite were recognized. A simple change in the way atoms are arranged geometrically can drastically alter their properties.

Diamond is network of tetrahedrons in which each carbon is joined with 4 other carbon atoms and so on. This forms a network which is the hardest material in the world. It sparkles in the light as the light is refracted at so many faces and unable to escape.

Graphite on the other hand is the form in which carbon atoms form honeycomb structures of hexagons joined to each other in the layers. The attraction between layers is not much and layers can slip over one another giving it a lubrication ability. Since there are are free electrons between the layers on each carbon, they form a tunnel in which electrons can move. Thus graphite also conducts electricity.

Now comes the Graphene. If you peel each layer, you have a two dimensional material which is thinnest material in the world. It is only 1 carbon atom thick and but at the same time it is the strongest material in the world, 100 times stronger than the steel.

Only limitation presently is its manufacture on commercial level in the purest form because contamination of even in single alien atom can spoil all the properties.

So many uses are already envisaged for this material. Since it conducts electricity better than any other material and unbreakable and very thin, future cellphones and other electronic touch screen gadgets shall be made from this. These shall be very thin, would not break on falling and could be folded to suit the pockets.

Another use shall be in the bionic devices because it is flexible and highly resistant to the corrosion caused by electrolytes present in the cells of human beings. These devices can be inserted at any place for many years without worrying for replacement.

At present scientists are trying to explore methods of making it on commercial scale. May be some genius like Kary Mullis device something like Polymerase chain reaction (PCR)  to multiply it million folds from a single copy. Nothing is impossible.

What Color are the Atoms?

Atoms are the smallest units of matter which are independent and have a definite address. Atoms of different elements are different in many aspects but size and atomic weight are the main attributes. I think there is no such thing as color of things. Color exists only when there is light.When the darkness falls, the color of things begins to dissolve and black color takes over everything. Black color thus obliterate all the differences due to colors. May be this is the reason why in Hindu mythology many Gods are dark complexioned. Take for example Rama, Krishna and Draupadi, all of them are dark in complexion. Although it is strange to explain why so many of Hindus prefer the fair color. So how can a thing have red color and black color at two instances of time? Light a bulb and again colors come back but there is different between the colors of things in different kinds of lights.

Sunlight is a mixture of many colors which are different waves. All the waves are the part of what is called light spectrum. Our eyes can see limited spectrum of light called visible spectrum which is from violet to red. Violet and beyond region called ultra violet have higher energy. On the opposite end is the red color and lower energy infra red. Birds and bees are endowed with more complex eyes and are capable of seeing into the infrared and ultra violet ranges also. The plants have exploited this capability and deposit substances on the flower strategically on flowers so that bees reach the target directly.

Our eyes have light receptors called cones and rods. They gather light from the target and send to the brain for generating a composite picture. The rods are more numerous than cones. The rods are meant for collecting the faint lights and operate when the light is dim like the sailors panning the stars in sky or when we are out in remote village on a clear night. Due to the plenty of light during the nights also these days, the services of the rods are seldom impressed upon. Now the main role is played by the cones. It is not known why these rods have not been traded with cones during the evolution.

When the light falls upon a substance, different energy centers in the substance become excited. These centers are electrons, atoms or molecules rotation, vibration of atoms joined with different kinds of bonds like single, double or triple. Depending upon the available spectrum of rays falling on the substance, those matching these centers are absorbed. This match is very much defined depending on the structure of the molecules.

From the visible spectrum, some of the wave length rays are absorbed. Those which does not match any center is not absorbed and reflected back. This is the color which reaches our eye and is responsible for the color which we attribute to the substance.

Most of the optical analytical instruments use monochromatic light beams to shine on the atoms and molecules. Monochromatic light is pure light beam of single energy and generally matches a particular wavelength emitted by an excited atoms of single elements. Thus they are able to determine the concentration of a particular element in a solution.