Carbocations

Carbocations are species bearing a formal "+" charge on carbon. The have sp² hybridization and trigonal planar geometry, with an empty p orbital on carbon, perpendicular to the plane containing the substituents (see diagrams shown to the right). Carbocations are "hypovalent" species, inasmuch as they have only three shared pairs of electrons around carbon, instead of the usual four. Of course, this incomplete octet around carbon makes carbocations very unstable and very reactive. Nevertheless, carbocations are known to be formed as intermediates in many types of organic reactions. For more details click here.

Courtesy: Dr. Thomas H. Eberlein, Penn State University

Langmuir Isotherm

The chemistry of adsorption is relatively complicated. A host of theories have been used in an attempt to understand the adsorption process. On this article, we will briefly introduce you to some of the math used to model adsorption, but you should be aware that this is only one model. 

We will assume an understanding of basic algebra throughout the discussion. You will need to know how to graph data and how to find the slope and y-intercept of a line. For more details click here.

Derivation of the Langmuir isotherm is here

Courtesy: http://water.me.vccs.edu

Racemic mixture

In chemistry, a racemic mixture, or racemate (pronounced /reɪˈsimeɪt/), is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule. The first known racemic mixture was "racemic acid", which Louis Pasteur found to be a mixture of the two enantiomeric isomers of tartaric acid. For more details click here.

 

Courtesy: http://www.princeton.edu

Valence Shell Electron Pair Repulsion Theory

VSEPR theory proposes that the geometric arrangement of terminal atoms, or groups of atoms about a central atom in a covalent compound, or charged ion, is determined solely by the repulsions between electron pairs present in the valence shell of the central atom. For more details click here.

Courtesy: http://intro.chem.okstate.edu

Valence Bond Theory and Hybrid Atomic Orbitals

The valence-bond approach considers the overlap of the atomic orbitals (AO) of the participation atoms to form a chemical bond. Due to the overlapping, electrons are localized in the bond region. The overlapping AOs can be of different types, for example, a sigma bond may be formed by the overlapping the following AOs.  For more details click here.

 Courtesy: http://www.science.uwaterloo.ca

Blog Special Edition

Calculations reveal carbon-carbon quadruple bond

 Courtesy: Andy Extance, http://www.rsc.org

Nanotechnology Basics: For Students and Other Learners

"The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big." — 

Richard Feynman, Nobel Prize winner in physics 

For more details click here

 

Courtesy: http://www.crnano.org

Basic Molecular Dynamics

A working definition of molecular dynamics (MD) simulation is technique by which one generates the atomic trajectories of a system of N particles by numerical integration of Newton’s equation of motion, for a specific inter-atomic potential, with certain initial condition (IC) and boundary condition (BC).

Consider, for example (see Figure), a system with N atoms in a volume . We can define its internal energy: E ≡ K +U, where K is the kinetic energy. For more details click here.

 Courtesy: Ju Li, Ohio State University, Columbus, OH, USA

Infrared Spectroscopy

The light our eyes see is but a small part of a broad spectrum of electromagnetic radiation. On the immediate high energy side of the visible spectrum lies the ultraviolet, and on the low energy side is the infrared. The portion of the infrared region most useful for analysis of organic compounds is not immediately adjacent to the visible spectrum, but is that having a wavelength range from 2,500 to 16,000 nm, with a corresponding frequency range from 1.9*10¹³ to 1.2*10¹⁴ Hz. For more details click here.

Courtesy: Dr. Reusch, http://www2.chemistry.msu.edu

Nuclear Chemistry

Nuclear chemistry is the sub-discipline of chemistry that is concerned with changes in the nucleus of elements. These changes are the source of radioactivity and nuclear power. Since radioactivity is associated with nuclear power generation, the concomitant disposal of radioactive waste, and some medical procedures, everyone should have a fundamental understanding of radioactivity and nuclear transformations in order to evaluate and discuss these issues intelligently and objectively. For more details click here. 

courtesy: http://nnhschemistry.pbworks.com

Courtesy: http://www.sas.upenn.edu

Analytical Chemistry

Analytical chemistry began in the late eighteenth century with the work of French chemist Antoine-Laurent Lavoisier and others; the discipline was further developed in the nineteenth century by Carl Fresenius and Karl Friedrich Mohr. As a pharmacist's apprentice in Frankfurt, Germany, Fresenius developed an extensive qualitative analysis scheme that, when it was later published, served as the first textbook of analytical chemistry. He built a laboratory at his house that opened in 1848. Here he trained students in gravimetric techniques that he had developed. Mohr developed laboratory devices such as the pinch clamp burette and the volumetric pipette. He also devised a colorimetric endpoint for silver titrations. It was his 1855 book on titrimetry, Lehrbuch der Chemisch-Analytischen Titromethode , that generated widespread interest in the technique.

Read more: http://www.chemistryexplained.com/A-Ar/Analytical-Chemistry.html#ixzz2E0G5tLhf

What is science?

The word "science" probably brings to mind many different pictures: a fat textbook, white lab coats and microscopes, an astronomer peering through a telescope, a naturalist in the rainforest, Einstein's equations scribbled on a chalkboard, the launch of the space shuttle, bubbling beakers …. All of those images reflect some aspect of science, but none of them provides a full picture because science has so many facets: more details can be found here.

These images all show an aspect of science, but a complete view of science is more than any particular instance.

 Courtesy: http://undsci.berkeley.edu

Nitrous Oxide - Laughing Gas

,"I am sure the air in heaven must be this wonder working gas of delight". So wrote poet Robert Southey of nitrous oxide, N₂O, also known as nitrogen oxide, dinitrogen monoxide, hyponitrous acid anhydride and facticious air. However, its most well known name is 'laughing gas' due to its intoxicating effects when inhaled.  For more details click here.

 Courtesy: Dr. Ewan Cameron and Dr. Paul May, School of Chemistry, University of Bristol

Polymers

Do you think that daily life would have been easier and colourful without the discovery and varied applications of polymers? The use of polymers in the manufacture of plastic buckets, cups and saucers, children’s toys, packaging bags, synthetic clothing materials, automobile tyres, gears and seals, electrical insulating materials and machine parts has completely revolutionised the daily life as well as the industrial scenario. Indeed, the polymers are the backbone of four major industries viz. plastics, elastomers, fibres and paints and varnishes. The word ‘polymer’ is coined from two Greek words: poly means many and mer means unit or part. The term polymer is defined as very large molecules having high molecular mass (10³-10⁷u).  For more details click here.

Courtesy: S. Anand, http://textbook.s-anand.net/

The Physiology Of Crying

There are three types of tears. The first type is basal tears. Because the eyeball's surface is riddled with irregularities, basal tears create a thin coat over the eye which smoothes out the surface. This helps to protect and lubricate the eye. Without this lubrication, a person would see a very distorted picture, and it would be painful when the eyeball moves. The eye needs this coating all the time so the body must constantly replace these tears due to the loss caused by evaporation. A typical person will produce five to ten ounces a day. In addition, basal tears contain antibacterial chemicals.

Read more: Crying - The Physiology Of Crying - Tears, Eye, Basal, and Irritant - JRank Articles http://social.jrank.org/pages/170/Crying-Physiology-Crying.html#ixzz2DIyBUxXf

Reactions of Alkanes

The alkanes and cycloalkanes, with the exception of cyclopropane, are probably the least chemically reactive class of organic compounds. Despite their relative inertness, alkanes undergo several important reactions that are discussed in the following section. For more click here.

Courtesy: Dr. William Reusch, http://www2.chemistry.msu.edu

Rubber - Chemistry

Rubber is an elastomer—that is, a polymer that has the ability to regain its original shape after being deformed. Rubber is also tough and resistant to weathering and chemical attack. Elastomers can be naturally occurring polymers, such as natural rubber, or they can be synthetically produced substances, such as butyl rubber, Thiokol, or neoprene. For a substance to be a useful elastomer it must possess a high molecular weight and a flexible polymer chain. 

Read more: http://www.chemistryexplained.com/Ru-Sp/Rubber.html#ixzz2D7RS7ypY

Modern Strategies in Organic Catalysis

Enantioselective organocatalysis has become a field of central importance for the asymmetric synthesis of chiral molecules. In the last ten years alone, this field has grown at an extraordinary pace from a small collection of chemically unique reactions to a thriving area of general concepts, atypical reactivities, and widely applicable reactions. Moreover, novel modes of substrate activation have been achieved using organic catalysts that can now deliver unique, orthogonal, or complementary selectivities in comparison to many established metal-catalyzed transformations. For more details click here.

Image courtesy of Prof. D. Savoia

Courtesy: Dr. Gérald Lelais, Professor D. W. C. MacMillan, http://www.princeton.edu

What is Astrochemistry?

Astrochemistry is the study of the chemical elements found in outer space, generally on larger scales than the Solar System, particularly in molecular gas clouds, and the study of their formation, interaction and destruction. As such, it represents an overlap of the disciplines of astronomy and chemistry. On the Solar System scale, the study of chemical elements is usually called cosmochemistry.  For more details about astrochemistry click here.

Photo courtesy of Dr. McCall Research Group 2012

Courtesy: Dr. Guido W. Fuchs

Rationale for Studying Physical Chemistry

The various rationales for studying physical chemistry, and speci fically the theoretical component  thereof are presented in what is hoped in THIS coherent package.

 

Courtesy: Dr. C. W. David

Molecular Orbital Concepts

The overlap of the two atomic orbitals (AO’s) results in the formation of two molecular orbitals (MO’s), one of which is lower in energy than the original AO’s (the bonding MO or BMO) and the other higher in energy than the original AO’s (the antibonding MO or ABMO). For more Click Here.

http://www.chem.ufl.edu

Courtesy:  http://research.cm.utexas.edu

Antioxidant Activities of Flavonoids

Flavonoids are compounds found in fruits, vegetables, and certain beverages that have diverse beneficial biochemical and antioxidant effects. Their dietary intake is quite high compared to other dietary antioxidants like vitamins C and E. The antioxidant activity of flavonoids depends on their molecular structure, and structural characteristics of certain flavonoids found in hops and beer confer surprisingly potent antioxidant activity exceeding that of red wine, tea, or soy. For more information click here.

Courtesy: Dr. Donald R. Buhler,  Dr. Cristobal Miranda

Click Chemistry

The term "click chemistry" was introduced by K. Barry Sharpless et al. and denotes the development of a set of powerful, highly reliable, and selective reactions for the rapid synthesis of useful new compounds and combinatorial libraries through heteroatom links. For more details follow this link.

Courtesy: Prof. K. B. Sharpless and co-workers

Atmospheric Chemistry and Greenhouse Gases

Currently, tropospheric ozone (O3) is the third most important greenhouse gas after carbon dioxide (CO2) and methane (CH4). It is a product of photochemistry, and its future abundance is controlled primarily by emissions of CH4, carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOC). There is now greater confidence in the model assessment of the increase in tropospheric O3 since the pre-industrial period, which amounts to 30% when globally averaged, as well as the response to future emissions. For scenarios in which the CH4 abundance doubles and anthropogenic CO and NOx emissions triple, the tropospheric O3 abundance is predicted to increase by an additional 50% above today’s abundance. For more Click Here.

Photo courtesy of http://phys-sci.colorado.edu

Courtesy: http://www.grida.no/climate

Humphry Davy

Humphry Davy named chlorine (Cl, element 17), 1810. Chlorine had been called oxymuriatic acid.

Humphry Davy (1778–1829), son of an impoverished Cornish woodcarver, rose meteorically to become a leader in the reformed chemistry movement initiated by Antoine-Laurent Lavoisier—albeit a critic of some of its basic premises—and a pioneer in the new field of electrochemistry. For more about Humphry Davy Click Here.

Courtesy: http://www.chemheritage.org

Fullerenes

The 1996 Nobel Prize for Chemistry has been won by Harold W. Kroto, Robert F. Curl and Richard E. Smalley for their discovery in 1985 of a new allotrope of carbon, in which the atoms are arranged in closed shells. The new form was found to have the structure of a truncated icosahedron, and was named Buckminsterfullerene, after the architect Buckminster Fuller who designed geodesic domes in the 1960's. For more click here.

 

 
Courtesy: Dr. Peter Unwin

Biosynthesis of Amino Acids

Click Here for the detailed description of Biosynthesis of Amino Acids

More about Amino Acids Here.

Courtesy: Dr. Bryant Miles and http://swift.cmbi.ru.nl

Enols, Enolates and Tautomerism

enols are compounds that have alcohol groups, -OH, substituted directly onto alkenes, C=C, hence "alkene-ols" or enols.

Enolates are the conjugate bases or anions of enols (like alkoxides are the anions of alcohols) and can be prepared using a base.

Click here for more

 Courtesy: Dr. Ian Hunt, Department of Chemistry, University of Calgary

Point Group Symmetry

The symmetry of a molecule is determined by the existence of symmetry operations performed with respect to symmetry elements. A symmetry element is a line, a plane or a point in or through an object, about which a rotation or reflection leaves the object in an orientation indistinguishable from the original. For more click here or here.

Courtesy: Prof. Reusch, http://www2.chemistry.msu.edu  and
                  Margaret Kastner, Timathy Medlock and Kristy Brown

 

Bragg's Law and Diffraction:

Bragg's Law refers to the simple equation:

n = 2d sin 

derived by the English physicists Sir W.H. Bragg and his son Sir W.L. Bragg in 1913 to explain why the cleavage faces of crystals appear to reflect X-ray beams at certain angles of incidence (theta, ). The variable d is the distance between atomic layers in a crystal, and the variable lambda is the wavelength of the incident X-ray beam (see applet); n is an integer. For more click here.

Courtesy: http://skuld.bmsc.washington.edu 

Major Types Of Chemical Compounds In Plants & Animals

Living systems can be organized into the following levels or categories, starting with the simplest units and proceeding to the largest and most complex levels of organization:

Subatomic particles (electrons, protons and neutrons) form atoms (hydrogen, helium, oxygen, iron, etc.) which form molecules (water, glucose, cellulose, etc.) which form complex macromolecules (glycoproteins, DNA, RNA, etc.) which form subcellular units called organelles (nucleus, mitochondrion, chloroplast, etc.) which form cells which form tissues (muscle, nerve, adipose, epithelial, etc.) which form organs (brain, heart, liver, root, leaf, etc.) which form an individual organism. 

All of the elements are listed in a periodic table by their atomic number or number of protons. In a neutral atom the number of protons is equal to the number of electrons. For more click here.

Courtesy: W. P. Armstrong, http://waynesword.palomar.edu 

Markovnikov's Rule

This is an empirical rule based on Markovnikov's experimental observations on the addition of hydrogen halides to alkenes.

The rule states that : "when an unsymmetrical alkene reacts with a hydrogen halide to give an alkyl halide, the hydrogen adds to the carbon of the alkene that has the greater number of hydrogen substituents, and the halogen to the carbon of the alkene with the fewer number of hydrogen substituents"

Courtesy: Dr. Ian Hunt, Department of Chemistry, University of Calgary

What is Green Chemistry

The term green chemistry is defined as: The invention, design and application of chemical products and processes to reduce or to eliminate the use and generation of hazardous substances. For more click here.

Courtesy: http://www.incaweb.org

Top 15 Chemical Additives in Your Food

We don't just want our food to taste good these days: It also has to look good. As a result, food producers use any of 14,000 laboratory-made additives to make our food appear fresher, more attractive or last longer on the shelf.

monosodium glutamate (MSG)

1. 1-METHYLCYCLOPROPENE
2. ARTIFICIAL COLORS
3. ARTIFICIAL FLAVORING
4. ASPARTAME
5. ASTAXANTHIN
6. BENZOIC ACID/SODIUM BENZOATE
7. BHA (BUTYLATED HYDROXYANISOLE) AND BHT (BUTYLATED HYDROXYTOLUENE)
8. CANTHAXANTHIN
9. EMULSIFIERS
10. HIGH-FRUCTOSE CORN SYRUP
11. MONOSODIUM GLUTAMATE (MSG)
12. OLESTRA
13. PARTIALLY-HYDROGENATED OILS
14. POTASSIUM BROMATE
15. SODIUM NITRITE AND NITRATE

 Courtesy and Read more at: http://phys.org/news183110037.html#jCp

The Photoelectric Effect

The most dramatic prediction of Maxwell's theory of electromagnetism, published in 1865, was the existence of electromagnetic waves moving at the speed of light, and the conclusion that light itself was just such a wave.  Click me to find out more.

Courtesy: Michael Fowler, University of Virginia

Molecule of the Week - Lucifer Yellow

Molecule of the Week - Lucifer Yellow

The dye’s fluorescence under UV light makes it ideal for visualizing living and fixed cells. The lithium salt is the most water-soluble, but ammonium and potassium salts are also used.

Chemical Bond

A chemical bond is an attraction between atoms brought about by a sharing of electrons between to atoms or a complete transfer of electrons. There are three types of chemical bonds: More find out here.

Courtesy: http://staff.jccc.net

Black Body Radiation

Do not all fix’d Bodies, when heated beyond a certain degree, emit Light and shine; and is not this Emission perform’d by the vibrating motion of its parts? For more click here.

Courtesy: Dr. Michael Fowler, University of Virginia

Aromatic Substitution Reactions

The chemical reactivity of benzene contrasts with that of the alkenes in that substitution reactions occur in preference to addition reactions. Find out more details here.

Courtesy: http://www2.chemistry.msu.edu

NANOTECHNOLOGY INTRODUCTION

What is Nanotechnology?

The term "nanotechnology" has evolved over the years via terminology drift to mean "anything smaller than microtechnology," such as nano powders, and other things that are nanoscale in size, but not referring to mechanisms that have been purposefully built from nanoscale components.  For more details click here.

smaller

faster

better

the nanoscale mantra

Courtesy: http://www.nanotech-now.com

Announcement

Blog's Special Edition

FAC blog's special edition column will start soon. Initially it will be on monthly basis. Later, will be upgraded to weekly edition. Thanks to all for those who have given strong support and valuable suggestions. Keep visiting the blog and continue your valuable suggestions.

Thanks to all

Have nice day

Administrator

 

Organoboron Chemistry

Boron in Organic Synthesis

Courtesy: WINPLT, http://www.chem.wisc.edu

Rutgers Researchers Say Daily Drinking Can Be Risky

Rutgers Researchers Say Daily Drinking Can Be Risky

Great art in a test tube

2010 Nobel Prize in Chemistry: Creating Complex Carbon-Based Molecules Using Palladium

New ways of linking carbon atoms together has allowed scientists to make medicines and better electronics. (Credit: iStockphoto/Liang Zhang)

 Courtesy: http://www.nobelprize.org

World University Rankings

The Times Higher Education World University Rankings 2012-2013 powered by Thomson Reuters are the only global university performance tables to judge world class universities across all of their core missions - teaching, research, knowledge transfer and international outlook. The top universities rankings employ 13 carefully calibrated performance indicators to provide the most comprehensive and balanced comparisons available, which are trusted by students, academics, university leaders, industry and governments. 

More details are here

Courtesy: Thomson Reuters