Химия. Экология. Медицина



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GREAT CHEMISTS

Iva Jankovic, group 25. Science adviser is Olga Levashova.


There were many great chemists in history, as well as modern chemistry scientists. As medical students we should know more about some of them, if not all.

1. Robert Boyle is scientist known as first “Modern Chemist”. He was born in Ireland in 1627, and died in 1691. He is famous because was an early proposer of the elemental nature of matter and the nature of vacuum. He was also one of the firsts to apply scientific method. His famous book is called “The Skeptical Chemist”.

2. Antoine Lavoisier is a French chemist (1743-1794) known as “The Father of Modern Chemistry”. He explained the relationship between oxygen and metals, role of oxygen in plant respiration and animals and showed that water was made of hydrogen and oxygen, and that air was composed mainly of oxygen and nitrogen in its gaseous state.

3. John Dalton (1766-1844) is an English scientist who identified and presented atomic theory. He also did a research on color blindness and identified chemical compounds and reactions affected by interaction between atoms.

4. Dmitri Mendeleev (1834-1907) is Russian scientist who created the periodic table of elements.

5. Rosalind Franklin (1920-1958) was an English scientist who discovered DNA structure in genetics.

6. Louis Pasteur (1822-1895) is a French scientist who discovered the process of Pasteurization of vaccines for rabies and anthrax. He also discovered the asymmetrical molecular structure on certain crystals.

7. Marie Curie (1867-1934) was Polish scientist who discovered Polonium and Radium, and won a Nobel prize in 1911.

These are some of the great chemists with big discoveries. There are many more of then that we should know about since they did something important for our world and society.

ERNEST RUTHERFORD

Abdulrahman Abughadeh, group 25. Science adviser is Olga Levashova.


Ernest Rutherford, 1st Baron Rutherford of Nelson (30 August 1871 – 19 October 1937) was a New Zealand-born physicist who became known as the father of nuclear physics considers him to be the greatest experimentalist since Michael Faraday (1791–1867).

In early work he discovered the concept of radioactive half-life, proved that radioactivity involved the transmutation of one chemical element to another, and also differentiated and named alpha and beta radiation. This work was done at McGill University in Canada. It is the basis for theNobel Prize in Chemistry he was awarded in 1908 "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances".

Rutherford moved in 1907 to the Victoria University of Manchester (today University of Manchester) in the UK, where he and Thomas Roydsproved that alpha radiation was helium ions. Rutherford performed his most famous work after he became a Nobel laureate. In 1911, although he could not prove that it was positive or negative, he theorized that atoms have their charge concentrated in a very small nucleus,and thereby pioneered the Rutherford model of the atom, through his discovery and interpretation of Rutherford scattering in his gold foil experiment. He is widely credited with first "splitting the atom" in 1917 in a nuclear reaction between nitrogen and alpha particles, in which he also discovered (and named) the proton.

CARBON

Asma Zain Alabden Abd Alrhem, group 25. Science adviser is Olga Levashova.


Carbon (from Latin: carbo "coal") is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. There are three naturally occurring isotopes, with 12C and 13C being stable, while 14C is radioactive, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity.

There are several allotropes of carbon of which the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form. For example, diamond is highly transparent, while graphite is opaque and black. Diamond is the hardest naturally-occurring material known, while graphite is soft enough to form a streak on paper (hence its name, from the Greek word "γράφω" which means "to write"). Diamond has a very low electrical conductivity, while graphite is a very good conductor. Under normal conditions, diamond, carbon nanotube and graphene have the highest thermal conductivities of all known materials.

All carbon allotropes are solids under normal conditions with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen. The most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and other transition metal carbonyl complexes. The largest sources of inorganic carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil and methane clathrates. Carbon forms more compounds than any other element, with almost ten million pure organic compounds described to date, which in turn are a tiny fraction of such compounds that are theoretically possible under standard conditions.

Carbon is the 15th most abundant element in the Earth's crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is present in all known life forms, and in the human body carbon is the second most abundant element by mass (about 18.5%) after oxygen. This abundance, together with the unique diversity of organic compounds and their unusual polymer-forming ability at the temperatures commonly encountered on Earth, make this element the chemical basis of all known life.

The different forms or allotropes of carbon (see below) include the hardest naturally occurring substance, diamond, and also one of the softest known substances, graphite. Moreover, it has an affinity for bonding with other small atoms, including other carbon atoms, and is capable of forming multiple stable covalent bonds with such atoms. As a result, carbon is known to form almost ten million different compounds; the large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements. At atmospheric pressure it has no melting point as its triple point is at 10.8 ± 0.2 MPa and 4,600 ± 300 K (~4,330 °C or 7,820 °F), so it sublimes at about 3,900 K.

Carbon sublimes in a carbon arc which has a temperature of about 5,800 K (5,530 °C; 9,980 °F). Thus, irrespective of its allotropic form, carbon remains solid at higher temperatures than the highest melting point metals such as tungsten or rhenium. Although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature.

Carbon compounds form the basis of all known life on Earth, and the carbon-nitrogen cycle provides some of the energy produced by the Sun and other stars. Although it forms an extraordinary variety of compounds, most forms of carbon are comparatively unreactive under normal conditions. At standard temperature and pressure, it resists all but the strongest oxidizers. It does not react with sulfuric acid, hydrochloric acid, chlorine or any alkalis. At elevated temperatures carbon reacts with oxygen to form carbon oxides, and will reduce such metal oxides as iron oxide to the metal.

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