General properties of pentarylene

Like the particles of a solid, particles in a liquid are subject to intermolecular attraction; however, liquid particles have more space between them, so they are not fixed in position. The attraction between the particles in a liquid keeps the volume of the liquid constant.

Prediction z

The movement of the particles causes the liquid to be variable in shape. Liquids will flow and fill the lowest portion of a container, taking on the shape of the container but not changing in volume.

The limited amount of space between particles means that liquids have only very limited compressibility. This cohesive "stickiness" accounts for the surface tension of a liquid. Surface tension can be thought of as a very thin "skin" of particles that are more strongly attracted to each other than they are to the particles surrounding them. As long as these forces of attraction are undisturbed, they can be surprisingly strong.

For example, the surface tension of water is great enough to support the weight of an insect such as a water skipper.

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Geological Survey. Cohesive forces are greatest beneath the surface of the liquid, where the particles are attracted to each other on all sides. Particles at the surface are more strongly attracted to the identical particles within the liquid than they are to the surrounding air.

This accounts for the tendency of liquids to form spheres, the shape with the least amount of surface area. When these liquid spheres are distorted by gravity, they form the classic raindrop shape. Particles of a liquid will not only be attracted to one another, but they are generally attracted to the particles that make up the container holding the liquid.

Particles of the liquid are drawn up above the surface level of the liquid at the edges where they are in contact with the sides of the container.

Ketone functional group

The combination of cohesive and adhesive forces means that a slight concave curve, known as the meniscus, exists at the surface of most liquids.

The most accurate measurement of the volume of a liquid in a graduated cylinder will be observed by looking at the volume marks closest to the bottom of this meniscus. One example of capillary action is when someone collects a sample of blood by touching a tiny glass tube to the blood droplet on the tip of a pricked finger.

A liquid that flows very slowly is said to be more viscous than a liquid that flows easily and quickly. A substance with low viscosity is considered to be thinner than a substance with higher viscosity, which is usually thought of as being thicker.

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For example, honey is more viscous than water. Honey is thicker than water and flows more slowly. Viscosity can usually be reduced by heating the liquid. When heated, the particles of the liquid move faster, allowing the liquid to flow more easily.

Because the particles of a liquid are in constant motion, they will collide with one another, and with the sides of the container.

general properties of pentarylene

Such collisions transfer energy from one particle to another. When enough energy is transferred to a particle at the surface of the liquid, it will eventually overcome the surface tension holding it to the rest of the liquid. As the faster particles escape, the remaining particles have lower average kinetic energy, and the temperature of the liquid cools. This phenomenon is known as evaporative cooling. Volatility is more often a property of liquids, but some highly volatile solids may sublime at normal room temperature.

Sublimation happens when a substance passes directly from solid to gas without passing through the liquid state. When a liquid evaporates inside a closed container, the particles cannot escape the system.The alkaline earth metals are one group of elements on the periodic table. The elements highlighted in yellow on the periodic table in the graphic belong to the alkaline earth element group. Here is a look at the location and the properties of these elements:. The alkaline earths are the elements located in Group IIA of the periodic table.

This is the second column of the table. The list of elements that are alkaline earth metals is short. In order of increasing atomic number, the six element names and symbols are:. If element is produced, it will most likely be a new alkaline earth metal. Presently, radium is the only one of these elements that is radioactive with no stable isotopes.

Element would be radioactive, too.

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All of the alkaline earths except magnesium and strontium have at least one radioisotope that occurs naturally. The alkaline earths possess many of the characteristic properties of metals. Alkaline earths have low electron affinities and low electronegativities. As with the alkali metalsthe properties depend on the ease with which electrons are lost.

The alkaline earths have two electrons in the outer shell. They have smaller atomic radii than the alkali metals. The two valence electrons are not tightly bound to the nucleus, so the alkaline earths readily lose the electrons to form divalent cations.

The alkaline earths get their names from their oxides, which were known to humankind long before the pure elements were isolated. These oxides were called beryllia, magnesia, lime, strontia, and baryta. The word "earth" in this use comes from an old term used by chemists to describe a nonmetallic substance that did not dissolve in water and resisted heating. Share Flipboard Email. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph.This article was written by Jack Lloyd.

He has over two years of experience writing and editing technology-related articles. He is technology enthusiast and an English teacher.

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Properties of the Basic Metals Element Group

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Click once the file for which you want to see and change properties. You may need to select the file's location e.These metrics are regularly updated to reflect usage leading up to the last few days. Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts. The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online.

Clicking on the donut icon will load a page at altmetric. Find more information on the Altmetric Attention Score and how the score is calculated. Cite this: Chem. Article Views Altmetric. Citations Note: In lieu of an abstract, this is the article's first page. Cited By. This article is cited by publications. Gwaltney, Colleen N. The Journal of Organic Chemistry85 19 Rathnamalala, Jacqueline N.

Gayton, Austin L. Dorris, Shane A. Autry, William Meador, Nathan I. Hammer, Jared H. Delcamp, Colleen N. The Journal of Organic Chemistry84 20 The Journal of Physical Chemistry C36 The Journal of Organic Chemistry84 15 The Journal of Physical Chemistry A19 ACS Omega4 3 Chemistry of Materials30 24 Journal of the American Chemical Society51 Bonardi, F. Morlet-Savary, C.These metrics are regularly updated to reflect usage leading up to the last few days.

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Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. Thus far, ruthenium II bipyridyl complexes have proven to be the most efficient TiO 2 sensitizers in dye-sensitized solar cells.

However, a gradual increment in the highest power conversion efficiency has been recognized in the past decade. More importantly, considering that ruthenium is a rare metal, novel dyes without metal or using inexpensive metal are desirable for highly efficient dye-sensitized solar cells. Porphyrins possess an intense Soret band at nm and moderate Q bands at nm. Nevertheless, the poor light-harvesting properties relative to the ruthenium complexes have limited the cell performance of porphyrin-sensitized TiO 2 cells.

On the basis of the strategy, the cell performance of porphyrin-sensitized solar cells has been improved intensively by the enhanced light absorption. Phthalocyanines exhibit strong absorption around and nm and redox features that are similar to porphyrins. However, the cell performance was poor, owing to strong aggregation and lack of directionality in the excited state.

As a result, the power conversion efficiency of up to 3. Perylenes are well-known as chemically, thermally, and photophysically stable dyes and have been used in various optical devices and applications. Nevertheless, the power conversion efficiency remained low compared to other organic dyes.

The origin of such limited cell performance is the poor electron-donating abilities of the perylenes, which makes it difficult to inject electrons from the excited singlet state of the perylenes to the conduction band of the TiO 2 electrode efficiently. View Author Information. Cite this: Acc. Article Views Altmetric. Citations Abstract Recently, dye-sensitized solar cells have attracted much attention relevant to global environmental issues. Cited By. This article is cited by publications.

general properties of pentarylene

Organic Letters22 18 ACS Omega4 12 The Journal of Physical Chemistry C26 Journal of the American Chemical Society25 ACS Energy Letters4 4 The Journal of Physical Chemistry C14Bleachsolid or liquid chemical used to whiten or remove the natural colour of fibresyarnsother textilesand paper.

In textile finishing, the bleaching process is used to produce white cloth, to prepare fabrics for other finishes, or to remove discoloration that has occurred in other processes. Bleach is also used as a disinfectant because of its microbicidal properties. Chlorinesodium hypochloritecalcium hypochlorite, and hydrogen peroxide are commonly used as bleaches.

Sunlight was the chief bleaching agent up to the discovery of chlorine in by Swedish chemist Karl Wilhelm Scheele and the demonstration of its bleaching properties in by French chemist Claude Berthollet.

Bleaching powdera solid combination of chlorine and slaked lime, introduced in by Scottish chemist Charles Tennantwas thereafter produced in large quantity to bleach cloth and paper.

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It had the same effect as chlorine and could be more easily handled and shipped, but it was unstable and contained a large proportion of inert material. It remained the standard bleaching agent until the s, but then it was gradually replaced by liquefied chlorine and solutions of sodium hypochlorite.

In the production of bleaching powder, slaked lime spread on the floors of large rectangular chambers of lead or concrete is exposed to chlorine gas; or lime is propelled through horizontal tubes that are fed with the gas.

Hydrogen peroxide is commonly used to bleach cotton cloth, with sodium chlorite and sodium hypochlorite as alternatives. Wood and animal fibres are bleached by acidic reducing agents such as sulfur dioxide. In the pulp and paper industry chlorine dioxide, hydrogen peroxide, sodium peroxide, sulfur dioxide, sodium bisulfite, and sodium hydrosulfite are commonly used. Synthetic fibres are bleached with either oxidizing or reducing agents, depending on their chemical composition.

Optical bleaches, fluorescent white chemicals giving off a bluish-white light, are not true bleaches. Various bleach solutions are used as disinfectants.

general properties of pentarylene

For example, dilute about 5 percent sodium hypochlorite solutions are used to sanitize food-processing equipment. Stronger solutions, ranging from about 10 to 20 percent bleach, may be used in hospitals, laboratories, and other settings where sanitization against potentially infectious microorganisms is critical. Article Media. Info Print Cite. Submit Feedback. Thank you for your feedback.

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Get exclusive access to content from our First Edition with your subscription. Subscribe today. Learn More in these related Britannica articles: fibre. Fibrein textile production, basic unit of raw material having suitable length, pliability, and strength for conversion into yarns and fabrics. A fibre of extreme length is a filament.

Fibres can occur naturally or can be produced artificially.Woodthe principal strengthening and nutrient-conducting tissue of trees and other plants and one of the most abundant and versatile natural materials.

Produced by many botanical species, including both gymnosperms and angiospermswood is available in various colours and grain patterns. It is strong in relation to its weight, is insulating to heat and electricityand has desirable acoustic properties.

As a material, wood has been in service since humans appeared on Earth. Today, in spite of technological advancement and competition from metalsplasticscementand other materials, wood maintains a place in most of its traditional roles, and its serviceability is expanding through new uses. In addition to well-known products such as lumberfurniture, and plywood, wood is the raw material for wood-based panels, pulp and paperand many chemical products.

Finally, wood is still an important fuel in much of the world. In botanical terms, wood is part of the system that conveys water and dissolved minerals from the roots to the rest of the plantstores food created by photosynthesisand furnishes mechanical support. It is produced by an estimated 25, to 30, species of plants, including herbaceous ones, though only 3, to 4, species produce wood that is suitable for use as a material.

Wood-producing forest trees and other woody plants are of two categories: gymnosperms and angiosperms. Gymnosperms, or cone-bearing trees, produce softwoodssuch as pine and spruceand angiosperms produce temperate and tropical hardwoodssuch as oakbeechteakand balsa. It should be noted that the distinction implied by hardwood and softwood is not true in all cases.

Some hardwoods—e. Wood is a material of great economic importance. It is found throughout the world and can be sustainably managed as a renewable resource—in contrast to coalores, and petroleumwhich are gradually exhausted. By means of its harvesting in forestsits transportation, its processing in workshops and industries, and its trade and use, wood provides jobs and supports economic development and, in some countries, basic subsistence.

Indicative of this importance is the continued high demand for wood and wood products. On a weight basis, the consumption of wood exceeds by far that of other materials. More than half of roundwood log production is consumed as fuel, mainly in less-developed countries. Production of paper and paperboard has shown the most rapid increase among wood products; this trend is expected to continue as consumption per person in the less-developed countries approaches that in the developed nations.

Rising world population is the driving force of increasing consumption of wood and consequent deforestation. The depletion of many forests, especially in the tropics, makes uncertain the provision of an adequate wood supply to satisfy the anticipated need. Article Media.

Info Print Print. Table Of Contents. Submit Feedback. Thank you for your feedback. Introduction Production and consumption of wood Harvesting of wood Management Marking, felling, and processing Utilization of wood Primary products Roundwood products Sawn wood Production at the sawmill Yield and grading Veneer Plywood and laminated wood Plywood Laminated wood Particleboard Fibreboard Pulp and paper Treatments Drying Preservation Chemical products Products of chemical processing Extractives Wood as a material Structure and composition Macrostructure Earlywood, latewood, and pores Heartwood and sapwood Rays and resin canals Radial and tangential sections Microstructure Ultrastructure and chemical composition Variation of structure and defects Properties of wood Sensory characteristics Density and specific gravity Hygroscopicity Shrinkage and swelling Mechanical properties Thermal properties Electric properties Acoustic properties Degradation Bark and bark products.

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What Are the Properties of the Alkaline Earth Metals?

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general properties of pentarylene

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