What Is An Atom?

 

What Is An Atom?

  Famous Female Scientists

 These scientists are Caroline Herschel, Mary Anning, Ada Lovelace, Maria Mitchell, Mary Kingsley, Annie Cannon, Marie Curie, Louise Boyd, Gerty Cori, Irene Joliet-Curie, Helen Taussig, Margaret Mead, Barbara McClintock, Dame Kathleen Lonsdale, Ruth Wakefield, Grace Murray Hoppe, Rachel Carson, Chien-Shiung Wu, Mary Leakey, Gertrude Elion, Rosalind Franklin, Rosalyn Yalow, Stephanie Kwolek, Jewel Plummer Cobb, Dian Fossey, Jane Goodall, Ada Yonath, Jocelyn Bell Burnell, Ellen Ochoa.

• Caroline Herschel: – She was a German astronomer. She was the first woman to discover a comet and also to receive honorary membership into the Royal Society. In 1783, Caroline Herschel discovered an open cluster which is known as NGC 2360.
• Mary Anning: – She was an amateur paleontologist and a fossil collector. Anning is sometimes referred as ‘the greatest fossilist the world ever knew’.
• Ada Lovelace: – Ada Lovelace was an English mathematician. She is considered the first computer programmer. She is best known for her work on Charles Babbage’s proposed general-purpose computer.
• Maria Mitchell: – She was the first professional female astronomer of America. She discovered a comet in 1847.
• Mary Kingsley: – She was an English explorer and scientific writer. Kingsley traveled throughout the West Africa.
• Annie Cannon: – Annie Cannon was an American astronomer. She studied bright southern hemisphere stars.
• Marie Curie: – Marie Curie was the first woman to win a Noble prize and the first scientist to win this in two different fields physics and chemistry. She discovered Polonium and Radium.
• Louise Boyd: – Louise Boyd was an American explorer. She made her first trip to arctic in 1926. In 1955, she became the first woman to charter a private plane and fly across the North Pole.
• Gerty Cori: – Gerty Cori was a biochemist. She was the first American woman to win a Noble prize in science. She has done some research work on the metabolic mechanism.
• Irene Joliet-Curie: – She was the daughter of Pierre and Marie Curie. Both her parents were scientists. She served as a nurse radiographer during the World War I.
• Helen Taussig: – She was an American cardiologist. She is also credited with the development of the first successful treatment of ‘blue baby’ syndrome.
• Margaret Mead: – Margaret Mead was an anthropologist. In 1979, she was awarded the highest civilian order of the United States, the Presidential Medal of Freedom.
• Barbara McClintock: – She was an American scientist. She is best known for her discovery of mobile genetic elements. In 1983, she won the Noble Prize in Physiology.

Global warming

 

Global warming

2011-2020 was the warmest decade recorded, with global average temperature reaching 1.1°C above pre-industrial levels in 2019. Human-induced global warming is presently increasing at a rate of 0.2°C per decade.

An increase of 2°C compared to the temperature in pre-industrial times is associated with serious negative impacts on to the natural environment and human health and wellbeing, including a much higher risk that dangerous and possibly catastrophic changes in the global environment will occur.

For this reason, the international community has recognised the need to keep warming well below 2°C and pursue efforts to limit it to 1.5°C.

Greenhouse gases

The main driver of climate change is the greenhouse effect. Some gases in the Earth's atmosphere act a bit like the glass in a greenhouse, trapping the sun's heat and stopping it from leaking back into space and causing global warming.

Many of these greenhouse gases occur naturally, but human activities are increasing the concentrations of some of them in the atmosphere, in particular:

• carbon dioxide (CO2)
• methane
• nitrous oxide
• fluorinated gases

CO2 produced by human activities is the largest contributor to global warming. By 2020, its concentration in the atmosphere had risen to 48% above its pre-industrial level (before 1750).

Other greenhouse gases are emitted by human activities in smaller quantities. Methane is a more powerful greenhouse gas than CO2, but has a shorter atmospheric lifetime. Nitrous oxide, like CO2, is a long-lived greenhouse gas that accumulates in the atmosphere over decades to centuries. Non-greenhouse gas pollutants, including aerosols like soot, have different warming and cooling effects and are also associated with other issues such as poor air quality.

Natural causes, such as changes in solar radiation or volcanic activity are estimated to have contributed less than plus or minus 0.1°C to total warming between 1890 and 2010.

Causes for rising emissions

• Burning coal, oil and gas produces carbon dioxide and nitrous oxide.
• Cutting down forests (deforestation). Trees help to regulate the climate by absorbing CO2 from the atmosphere. When they are cut down, that beneficial effect is lost and the carbon stored in the trees is released into the atmosphere, adding to the greenhouse effect.
• Increasing livestock farming. Cows and sheep produce large amounts of methane when they digest their food.
• Fertilisers containing nitrogen produce nitrous oxide emissions.
• Fluorinated gases are emitted from equipment and products that use these gases. Such emissions have a very strong warming effect, up to 23 000 times greater than CO2.

Chemistry

Chemistry

 Chemistry, the science that deals with the properties, composition, and structure of substances (defined as elements and compounds), the transformations they undergo, and the energy that is released or absorbed during these processes. Every substance, whether naturally occurring or artificially produced, consists of one or more of the hundred-odd species of atoms that have been identified as elements. Although these atoms, in turn, are composed of more elementary particles, they are the basic building blocks of chemical substances; there is no quantity of oxygen, mercury, or gold, for example, smaller than an atom of that substance. Chemistry, therefore, is concerned not with the subatomic domain but with the properties of atoms and the laws governing their combinations and how the knowledge of these properties can be used to achieve specific purposes.

The great challenge in chemistry is the development of a coherent explanation of the complex behaviour of materials, why they appear as they do, what gives them their enduring properties, and how interactions among different substances can bring about the formation of new substances and the destruction of old ones. From the earliest attempts to understand the material world in rational terms, chemists have struggled to develop theories of matter that satisfactorily explain both permanence and change. The ordered assembly of indestructible atoms into small and large molecules, or extended networks of intermingled atoms, is generally accepted as the basis of permanence, while the reorganization of atoms or molecules into different arrangements lies behind theories of change. Thus chemistry involves the study of the atomic composition and structural architecture of substances, as well as the varied interactions among substances that can lead to sudden, often violent reactions.

Chemistry also is concerned with the utilization of natural substances and the creation of artificial ones. Cooking, fermentation, glass making, and metallurgy are all chemical processes that date from the beginnings of civilization. Today, vinyl, Teflon, liquid crystals, semiconductors, and superconductors represent the fruits of chemical technology. The 20th century saw dramatic advances in the comprehension of the marvelous and complex chemistry of living organisms, and a molecular interpretation of health and disease holds great promise. Modern chemistry, aided by increasingly sophisticated instruments, studies materials as small as single atoms and as large and complex as DNA (deoxyribonucleic acid), which contains millions of atoms. New substances can even be designed to bear desired characteristics and then synthesized. The rate at which chemical knowledge continues to accumulate is remarkable. Over time more than 8,000,000 different chemical substances, both natural and artificial, have been characterized and produced. The number was less than 500,000 as recently as 1965.

Intimately interconnected with the intellectual challenges of chemistry are those associated with industry. In the mid-19th century the German chemist Justus von Liebig commented that the wealth of a nation could be gauged by the amount of sulfuric acid it produced. This acid, essential to many manufacturing processes, remains today the leading chemical product of industrialized countries. As Liebig recognized, a country that produces large amounts of sulfuric acid is one with a strong chemical industry and a strong economy as a whole. The production, distribution, and utilization of a wide range of chemical products is common to all highly developed nations. In fact, one can say that the “iron age” of civilization is being replaced by a “polymer age,” for in some countries the total volume of polymers now produced exceeds that of iron.

 

Why Are MINERALS Important?

Periodic table

 Periodic table 

This is a chart that shows all the known chemical elements. The table is made up of over a hundred squares. Each square represents one element. A square contains one or two letters that stand for the element’s name, and numbers that tell about that element’s properties.

The location of each square in the table tells many things about each element. First, the elements are organized by atomic number, or how many protons they have. Those on top of the chart have the fewest protons. An element’s place also shows how likely it is to react. It also shows how its electrons are arranged.

During the mid-1800s, many chemists looked for patterns that explained how elements interacted. Back then, scientists didn’t know about the protons, neutrons and electrons that make up atoms. But they did understand that elements had different atomic weights.  An atomic weight is the average weight of one atom of an element.

In 1869, the Russian chemist Dimitri Mendeleev lined up the 63 known elements in order by their atomic weights. He saw trends in the elements’ properties that varied over specific intervals, or periods. Other scientists were working on their own periodic tables, but Mendeleev published his table first.

The periodic table continued to grow as scientists discovered more elements. These include the noble gases, identified in 1890. This is a group of elements such as helium that don’t like to react with other elements. Starting in the 1940s, scientists found many new elements by colliding atoms or pieces of atoms.

At the end of 2018, chemists confirmed four elements that had never been observed before. That brought the number of known elements to 118 and completed the 7th row of the table.

Chemical engineering

 Chemical engineering

Chemical engineering, the development of processes and the design and operation of plants in which materials undergo changes in their physical or chemical state. Applied throughout the process industries, it is founded on the principles of chemistry, physics, and mathematics.

The laws of physical chemistry and physics govern the practicability and efficiency of chemical engineering operations. Energy changes, deriving from thermodynamic considerations, are particularly important. Mathematics is a basic tool in optimization and modeling. Optimization means arranging materials, facilities, and energy to yield as productive and economical an operation as possible. Modeling is the construction of theoretical mathematical prototypes of complex process systems, commonly with the aid of computers.

History

Chemical engineering is as old as the process industries. Its heritage dates from the fermentation and evaporation processes operated by early civilizations. Modern chemical engineering emerged with the development of large-scale, chemical-manufacturing operations in the second half of the 19th century. Throughout its development as an independent discipline, chemical engineering has been directed toward solving problems of designing and operating large plants for continuous production.

Manufacture of chemicals in the mid-19th century consisted of modest craft operations. Increase in demand, public concern at the emission of noxious effluents, and competition between rival processes provided the incentives for greater efficiency. This led to the emergence of combines with resources for larger operations and caused the transition from a craft to a science-based industry. The result was a demand for chemists with knowledge of manufacturing processes, known as industrial chemists or chemical technologists. The term chemical engineer was in general use by about 1900. Despite its emergence in traditional chemicals manufacturing, it was through its role in the development of the petroleum industry that chemical engineering became firmly established as a unique discipline. The demand for plants capable of operating physical separation processes continuously at high levels of efficiency was a challenge that could not be met by the traditional chemist or mechanical engineer.

A landmark in the development of chemical engineering was the publication in 1901 of the first textbook on the subject, by George E. Davis, a British chemical consultant. This concentrated on the design of plant items for specific operations. The notion of a processing plant encompassing a number of operations, such as mixing, evaporation, and filtration, and of these operations being essentially similar, whatever the product, led to the concept of unit operations. This was first enunciated by the American chemical engineer Arthur D. Little in 1915 and formed the basis for a classification of chemical engineering that dominated the subject for the next 40 years. The number of unit operations—the building blocks of a chemical plant—is not large. The complexity arises from the variety of conditions under which the unit operations are conducted.

In the same way that a complex plant can be divided into basic unit operations, so chemical reactions involved in the process industries can be classified into certain groups, or unit processes (e.g., polymerizations, esterifications, and nitrations), having common characteristics. This classification into unit processes brought rationalization to the study of process engineering.

The unit approach suffered from the disadvantage inherent in such classifications: a restricted outlook based on existing practice. Since World War II, closer examination of the fundamental phenomena involved in the various unit operations has shown these to depend on the basic laws of mass transfer, heat transfer, and fluid flow. This has given unity to the diverse unit operations and has led to the development of chemical engineering science in its own right; as a result, many applications have been found in fields outside the traditional chemical industry.

Study of the fundamental phenomena upon which chemical engineering is based has necessitated their description in mathematical form and has led to more sophisticated mathematical techniques. The advent of digital computers has allowed laborious design calculations to be performed rapidly, opening the way to accurate optimization of industrial processes. Variations due to different parameters, such as energy source used, plant layout, and environmental factors, can be predicted accurately and quickly so that the best combination can be chosen.