Weak forces

Strong adsorbate-substrate forces lead to chemisorption, in which a chemical bond is fomied. By contrast, weak forces result inphysisorption, as one calls non-chemical physical adsorption. 

Induced dipole/mduced dipole attractions are very weak forces individually but a typical organic substance can participate m so many of them that they are collectively the most important of all the contributors to mtermolecular attraction m the liquid state They are the only forces of attraction possible between nonpolar molecules such as alkanes... 

The stmcture of the particles inside the nucleus was the next question to be addressed. One step in this direction was the discovery of the neutron in 1932 by Chadwick, and the deterrnination that the nucleus was made up of positively charged protons and uncharged neutrons. The number of protons in the nucleus is known as the atomic number, Z. The number of neutrons is denoted by A/, and the atomic mass is thus A = Z - - N. Another step toward describing the particles inside the nucleus was the introduction of two forces, namely the strong force that holds the protons and neutrons together in spite of the repulsion between the positive charges of the protons, and the weak force that produces the transmutation by P decay. 

Sorption of nonionic, nonpolar hydrophobic compounds occurs by weak attractive interactions such as van der Waals forces. Net attraction is the result of dispersion forces the strength of these weak forces is about 4 to 8 kj/mol ( 1 2 kcal/mol). Electrostatic interactions can also be important, especially when a molecule is polar in nature. Attraction potential can develop between polar molecules and the heterogeneous sod surface that has ionic and polar sites, resulting in stronger sorption. 

Radiometric forces Weak forces that cause the motion of particulate matter, including diffusiophoresis, thermophoresis, and photophoresis. 

Weak Forces Maintain Biological Structure and Determine Biomolecular Interactions... 

Weak Forces Restrict Organisms to a Narrow Range of Environmental Conditions... 

Why is it important that weak forces, not strong forces, mediate biomolecnlar recognition ... 

Why does the central role of weak forces in biomolecnlar interactions restrict living systems to a narrow range of environmental conditions ... 

Accelerators are responsible for many fundamental discoveries as well as many practical applications. An example of a fundamental discovery was the observation of the W and Z particles that carry the weak force that is responsible, along with the strong and electromagnetic forces, for the fact that the sun shines. An example of a practical application is the use of accelerator beams to kill cancerous tumors in patients. 

Helium is a monatomic gas and, as yet, no stable compounds of helium have been found. The attractive forces between the atoms of helium are unusually weak, as shown by the normal boiling point. To liquefy helium, it must be cooled to — 268.9°C or 4.2°K. No other element or compound has a boiling point as low. Helium has another distinction which reflects these weak forces it is the only substance known which cannot be solidified at any temperature unless it is subjected to pressure. Helium becomes solid at 1.1 °K at a pressure of 26 atmospheres. 

Graphite is another solid form of carbon. In contrast to the three-dimensional lattice structure of diamond, graphite has a layered structure. Each layer is strongly bound together but only weak forces exist between adjacent layers. These weak forces make the graphite crystal easy to cleave, and explain its softness and lubricating qualities. 

The interest in this area may be seen to stem from the biological area where the phenomenon is well known and accounts for the regularity in the structure of natural proteins and polynucleotides. Such polymers are efficiently synthesized by enzymes which arc capable of organizing monomer units within regularly structured molecular-scale spaces and exploiting weak forces such as hydrogen bonds and Van der Waal forces to control the polymerization process.. 

Due to the relatively weak forces between the layers of MMT, water and other polar molecules can enter between the unit layers, causing the lattice to expand in the thickness direction. The charge deficiency on the sheet surface is typically balanced by exchangeable cations adsorbed between the unit layers and around their edges because of the substitution of ions of different valence. 

Primary structures are stabilized by covalent peptide bonds. Higher orders of structure are stabilized by weak forces—multiple hydrogen bonds, salt (electrostatic) bonds, and association of hydrophobic R groups. 

To answer Staudinger s critics, Carothers knew he had to resolve three issues. First, he would have to build one of Staudinger s macromolecules. Next, he would have to confirm that they were indeed long-chained molecules, not merely aggregates of smaller molecules, as others claimed. Finally, he would have to prove that the forces holding the chains together were ordinary valence bonds, rather than a mysterious weak force. 

As already mentioned, the HGT principle has been known for many years however, until about 15 years ago, it was regarded as only a weak force in the evolutionary events involved in the development of primeval cells, whose organisation must have been very simple. They probably had a loose structure which could easily be modified by HGT processes. An important characteristic of Woese s model is the nature of the evolutionary process Woese assumes that cell design could be achieved only by the overall performance of HGT. It was the community as a whole,... 

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