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Thursday, 27 July 2017

Points You Should Remember About Covalent Bonds


A covalent bond is a chemical bond that involves sharing of pairs of electronsbetween atoms. These pairs of electrons are known as bonding pairs or shared pair.
Covalent bond is also known as molecular bond. Covalent bonding arises between two atoms of the same element, or of elements which are close to each other in the periodic table. Covalent bonding occurs primarily between non-metals; but, it can also be witnessed between metals and non-metals. Covalent bonds are most likely to occur, when atoms have similar electro negativities.
History of covalence
The term covalence was first used in 1919 in regards to bonding, by Irving Langmuir in article of “Journal of the American Chemical Society”, titled "The Arrangement of Electrons in Atoms and Molecules". 
However, the idea of covalent bonding could be traced to Gilbert N. Lewis, numeral years before 1919, who in 1916 explained the sharing of electron pairs between atoms.
What are various types of covalent bonds?
There exist three types of covalent bonds which is based upon number of shared electron pairs.
Single covalent bond: Single covalent bonds between two atoms are formed, when there exist a mutual sharing of one electron pair. Single covalent bond is denoted by short single line (----).
Double covalent bond: Single covalent bonds between two atoms are formed when there exist mutual sharing of two electron pairs. Double covalent bond is denoted by short double line (=).
Triple covalent bond: Triple covalent bond is formed, when there is sharing of three electron pairs. This bond is denoted by triple short line. 
Polar covalent bond: When a covalent bond is formed between two different atoms, it is said as polar covalent bond.
Non-polar covalent bond: When a covalent bond is formed between two like atoms, it is said as non-polar covalent bond.

Read more. Points You Should Remember About Covalent Bonds

Linde to expand production capacity in Malaysia; invests €30 mn




Linde Malaysia Sdn Bhd (Linde), a member of The Linde Group said that it will invest €30 million to expand its gas and liquid production capacities in central Malaysia.
Linde will construct and commission a new gas and liquid producing air separation unit (ASU) at its site in Hicom Industrial Estate (Hicom). The new ASU will be integrated into the pipeline supply network of existing plants which Linde operates in Bukit Raja and Hicom.
The investment will enable Linde to meet forecast growth in the central Malaysian region through the next decade. The expansion project is expected to be completed by 2018. The facility will also form the cornerstone of a renewed and expanding oxygen supply scheme to leading Japanese glass manufacturer, Nippon Electric Glass Malaysia (NEGM).
“There continues to be a healthy growth momentum and expansion activities across a variety of industries in the central region. Our latest investment further strengthens Linde’s position as a reliable and efficient provider of top quality industrial gases to NEGM and other customers in Malaysia,” said Connell Zhang, managing director for Linde Malaysia.

AkzoNobel, Itaconix bio-based agreement enters commercial phase




AkzoNobel NV has finalised the first application agreement for bio-based polymers to result from its collaboration with Itaconix PLC.
Announced earlier this year, the joint development agreement involves AkzoNobel’s performance additives unit developing applications for Itaconix polymers to be used in the coatings and construction industries. Under the agreement, Itaconix will contribute its proprietary polymers from itaconic acid, which are obtained from sugars through fermentation.
“We are pleased to be announcing the first in a series of agreements to develop these polymers for commercial use. Being able to incorporate polymers made from renewable bio-based raw materials will give a significant sustainability advantage for our customers and also fits closely with our own Planet Possible sustainability agenda of doing more with less,” said Peter Nieuwenhuizen, RD&I director for AkzoNobel’s speciality chemicals business.
“In addition to applications in coatings and construction materials, bio-based polymers have the potential to be used in a range of other everyday essentials, ranging from improving water quality to cleaning and hygiene products,” added Nieuwenhuizen.

RPM appoints new president for industrial segment



RPM International Inc (RPM) said that David Reif, III, formerly group president of the RPM performance coatings group, has been appointed president – RPM industrial segment.
In this role, Reif will provide strategic direction to RPM’s industrial segment businesses. He will report to RPM’s president and chief operating officer (CEO) Ronald Rice.
Reif began his career at KPMG Peat Marwick in 1975 and joined Stonhard Inc in 1986 as executive VP and chief financial officer (CFO) and a minority owner. RPM acquired Stonhard in 1993. Since that time, Reif has served as CFO of RPM, president of its StonCor Group of operating companies, and in June of 2000 was appointed president and CEO of the RPM performance coatings group.
Additionally, RPM also announced the promotion of David Dennsteadt (currently VP) to group president of the RPM performance coatings group, a collection of companies that are global leaders in industrial high-performance coatings and waterproofing products including Carboline, Stonhard, USL and Fibergrate.
Greaves will report to Reif in his capacity as president - RPM industrial segment.

In search of new materials with exceptional properties




In an interview, Srinivasa Raghavan, Professor and Patrick & Marguerite Sung Chair, Department of Chemical & Biomolecular Engineering, University of Maryland (College Park) with Chemical Today Magazine discusses about his passion for inventing materials that can adapt to the environment and transform into something much better - to have a positive impact on the society.
The aim of our team is to invent new materials with exceptional properties. Our focus is primarily on “soft” matter and “complex” fluids ie, those with a jelly-like or gooey or slimy consistency. These are very important materials because we are all examples of soft matter ie, we are made up of cells that have a gel-like interior. Also, we are surrounded by soft matters everywhere, including the foods we eat (jelly, ketchup) and the consumer products we use (toothpaste, shampoo) etc.
One particular direction of our research is the creation of responsive or “smart” systems. That is, we invent materials that adapt to their environment, such as changing from one shape to another in response to the external temperature. We invent materials that can change its viscosity. We have made a fluid that is 1000 times as viscous as honey, but when we shine ultraviolet light on it, the fluid’s viscosity drops one million times and approaches that of water. When we then shine visible light, the fluid viscosity can be returned to its original value. Another example is a container or capsule that can hold drugs. This can travel through our blood, but the moment it reaches a particular destination (eg, a cancer tumour), it will open up and release its contents.

New triple-layered catalyst to split water into hydrogen, oxygen




Splitting water into hydrogen and oxygen to produce clean energy can be simplified with a single catalyst developed by scientists at Rice University and the University of Houston.
The electrolytic film produced at Rice and tested at Houston is a three-layer structure of nickel, graphene and a compound of iron, manganese and phosphorus. The foamy nickel gives the film a large surface, the conductive graphene protects the nickel from degrading and the metal phosphide carries out the reaction.
The research is published in the journal Nano Energy.
Rice chemist Kenton Whitmire and Houston electrical and computer engineer Jiming Bao and their labs developed the film to overcome barriers that usually make a catalyst good for producing either oxygen or hydrogen, but not both simultaneously.
“Regular metals sometimes oxidize during catalysis,” Whitmire said. “Normally, a hydrogen evolution reaction is done in acid and an oxygen evolution reaction is done in base. We have one material that is stable whether it’s in an acidic or basic solution.”
The discovery builds upon the researchers’ creation of a simple oxygen-evolution catalyst revealed earlier this year. In that work, the team grew a catalyst directly on a semiconducting nanorod array that turned sunlight into energy for solar water splitting.
Electrocatalysis requires two catalysts, a cathode and an anode. When placed in water and charged, hydrogen will form at one electrode and oxygen at the other, and these gases are captured. But the process generally requires costly metals to operate as efficiently as the Rice team’s catalyst.
The new catalyst also requires less energy, Whitmire said. “If you want to make hydrogen and oxygen, you have to put in energy, and the more you put in, the less commercially viable it is,” he said. “You want to do it at the minimum amount of energy possible. That’s a benefit of our material: The overpotential (the amount of energy required to trigger electrocatalysis) is small and quite competitive with other materials. The lower you can get it, the closer you come to making it as efficient as possible for water splitting.”

Scientists design new cathode for sodium-based batteries




Scientists at the Institute of Chemistry (IOC) of Chinese Academy of Sciences (CAS) and the US Department of Energy’s (DOE) Brookhaven National Laboratory have designed a new type of cathode that could make the mass production of sodium batteries more feasible.
Batteries based on plentiful and low-cost sodium are of great interest to both scientists and industry as they could facilitate a more cost-efficient production process for grid-scale energy storage systems, consumer electronics and electric vehicles.
Lithium batteries are commonly found in consumer electronics such as smartphones and laptop computers, but in recent years, the electric vehicle industry also began using lithium batteries, significantly increasing the demand on existing lithium resources.
“Just last year, the price of lithium carbonate tripled, because the Chinese electric vehicle market started booming,” said Xiao-Qing Yang, a physicist at the chemistry division of Brookhaven Lab and the lead Brookhaven researcher on this study.
In addition, the development of new electrical grids that incorporate renewable energy sources like wind and solar is also driving the need for new battery chemistries. Because these energy sources are not always available, grid-scale energy storage systems are needed to store the excess energy produced when the sun is shining and the wind is blowing.
Scientists have been searching for new battery chemistries using materials that are more readily available than lithium. Sodium is one of the most desirable options for researchers because it exists nearly everywhere and is far less toxic to humans than lithium.

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