Bishopshalt School is a secondary school and sixth form with academy status based in the London Borough of Hillingdon. It has specialisations in the performing arts. Between 2013 and 2014, the school was used for scenes in the BBC sitcom Big School; the current building within which the school is housed was built in 1858. The school dates back to 1907 when it was first established as Uxbridge County School in the Greenway, it was designed by the architect H. G. Crothall for the Middlesex Education Committee; the Middlesex Education Committee purchased the present site for £6900 in 1925 and in 1928 the school moved there. The original buildings in the Greenway became part of Uxbridge High School. On 6 October the school was opened by Sir John Reith, the Director-General of the BBC. Walter Wilks Sawtell was headmaster of the school from its founding in 1907 until 1929, he remained in the position to oversee the move of the school, before resigning to become rector of Madehurst in Sussex. The school name was changed to Bishopshalt School in 1930 to acknowledge it was no longer in Uxbridge.
It is derived from the history of the site as for 500 years the Bishops of Worcester rested at the grounds of the school on their journeys to and from London. A Cierva C.19 Mk.3 Autogiro landed on the school field in July 1931, piloted by the Cierva Autogiro Company's Flying Manager Reginald A. C. Brie, a former pupil of the school. During the Second World War, the school was used for rallies and inspections of the local Girls' Training Corps. Randalls of Uxbridge, a local family-owned department store, donated three oak chairs to the school in October 1949. In 1969, the school's air raid shelters were replaced by a car park; the shelters had been remained because of the threat of the Cold War. The London Borough of Hillingdon held council meetings in the school hall while the Civic Centre in Uxbridge was under construction. In 1977 the school changed from a grammar school to a comprehensive. An episode of Jeeves and Wooster starring Hugh Laurie and Stephen Fry was filmed in the school grounds.
The school has been used as a filming location, for the film adaptation of Angus and Perfect Snogging, directed by Gurinder Chadha, the BBC comedy Big School. The current Headmaster is Mr Kimberly Rowe, who started in September 2011. Prior Headteachers are: Mr David Bocock. Bishopshalt School specialises in the performing arts, it has its own large playing fields and an ornamental garden for the 6th form students. Bishopshalt has six'houses', five named after bishops that rested at the old mansion, on their first day out from London, going to Worcester in the days of horse-drawn coach travel. Cranmer, De Salis, Manor and Worcester are the houses; the school motto is Fidelis. De Salis house was named after a local family that included Bishop De Salis and his elder brother Cecil Fane De Salis, a benefactor and governor of the school and last owner of the nearby Dawley Court at Goulds Green. Bishopshalt School runs a dramatic society named Bishopshalt Operatic and Dramatic Society, known as BODS; the company is open to students at the school from the tenth to the thirteenth academic year.
They perform annually during December. The latest BODS show was-'Beauty and The Beast.' The Junior BODS are performed in June/July every year. The latest Junior BODS show was- Mary Poppins, it gets the third highest A level results in Hillingdon and above average results at GCSE. Bishopshalt recently won the Hillingdon Maths challenge for Year 7, they have a successful football team as well. Carla Mendonca, Actress Claire Richards, singer Neil Shipperley, footballer Warren Goodhind, footballer Ryan Watson, actor Bernard Miles, actor Raheem Kassam, former editor of Breitbart London and chief adviser to UKIP Leslie Clifford Bateman CMG, Malaysian politician Prof Vernon Bogdanor CBE, Professor of Government at the University of Oxford John Taylor Hughes, Anglican Suffragan bishop of Croydon 1956–1977 and to the Forces 1966–1975. Oswald Morris, cinematographer Bernard Miles, character actor and director Mel Read, Labour MEP for the East Midlands from 1999 to 2004 Nick Simper, Deep Purple bass guitarist Prof Robert Vaughan FRS, Professor of Pure Mathematics at Imperial College London from 1980 to 1998 and at Penn State University from 1999.
EPSRC Senior Fellow 1991–1996. John Arthur Watts, Conservative MP for Slough from 1983 to 1997, Leader of Hillingdon Borough Council from 1978 to 1984. Citations BibliographyPearce, Ken. Hillingdon Village. Stroud: Sutton Publishing ISBN 978-0-7509-4675-9 Bishopshalt School Website EduBase
Petroleum is a occurring, yellowish-black liquid found in geological formations beneath the Earth's surface. It is refined into various types of fuels. Components of petroleum are separated using a technique called fractional distillation, i.e. separation of a liquid mixture into fractions differing in boiling point by means of distillation using a fractionating column. It consists of occurring hydrocarbons of various molecular weights and may contain miscellaneous organic compounds; the name petroleum covers both occurring unprocessed crude oil and petroleum products that are made up of refined crude oil. A fossil fuel, petroleum is formed when large quantities of dead organisms zooplankton and algae, are buried underneath sedimentary rock and subjected to both intense heat and pressure. Petroleum has been recovered by oil drilling. Drilling is carried out after studies of structural geology, sedimentary basin analysis, reservoir characterisation have been completed, it is refined and separated, most by distillation, into a large number of consumer products, from gasoline and kerosene to asphalt and chemical reagents used to make plastics and pharmaceuticals.
Petroleum is used in manufacturing a wide variety of materials, it is estimated that the world consumes about 95 million barrels each day. The use of petroleum as fuel is controversial due to its impact on global warming and ocean acidification. Fossil fuels, including petroleum, need to be phased out by the end of 21st century to avoid "severe and irreversable impacts for people and ecosystems", according to the UN's Intergovernmental Panel on Climate Change; the word petroleum comes from Medieval Latin petroleum, which comes from Latin petra', "rock", Latin oleum, "oil". The term was used in the treatise De Natura Fossilium, published in 1546 by the German mineralogist Georg Bauer known as Georgius Agricola. In the 19th century, the term petroleum was used to refer to mineral oils produced by distillation from mined organic solids such as cannel coal, refined oils produced from them. Petroleum, in one form or another, has been used since ancient times, is now important across society, including in economy and technology.
The rise in importance was due to the invention of the internal combustion engine, the rise in commercial aviation, the importance of petroleum to industrial organic chemistry the synthesis of plastics, solvents and pesticides. More than 4000 years ago, according to Herodotus and Diodorus Siculus, asphalt was used in the construction of the walls and towers of Babylon. Great quantities of it were found on the banks of the river Issus, one of the tributaries of the Euphrates. Ancient Persian tablets indicate the medicinal and lighting uses of petroleum in the upper levels of their society; the use of petroleum in ancient China dates back to more than 2000 years ago. In I Ching, one of the earliest Chinese writings cites that oil in its raw state, without refining, was first discovered and used in China in the first century BCE. In addition, the Chinese were the first to use petroleum as fuel as early as the fourth century BCE. By 347 AD, oil was produced from bamboo-drilled wells in China. Crude oil was distilled by Arabic chemists, with clear descriptions given in Arabic handbooks such as those of Muhammad ibn Zakarīya Rāzi.
The streets of Baghdad were paved with tar, derived from petroleum that became accessible from natural fields in the region. In the 9th century, oil fields were exploited in the area around Azerbaijan; these fields were described by the Arab geographer Abu al-Hasan'Alī al-Mas'ūdī in the 10th century, by Marco Polo in the 13th century, who described the output of those wells as hundreds of shiploads. Arab and Persian chemists distilled crude oil in order to produce flammable products for military purposes. Through Islamic Spain, distillation became available in Western Europe by the 12th century, it has been present in Romania since the 13th century, being recorded as păcură. Early British explorers to Myanmar documented a flourishing oil extraction industry based in Yenangyaung that, in 1795, had hundreds of hand-dug wells under production. Pechelbronn is said to be the first European site where petroleum has been used; the still active Erdpechquelle, a spring where petroleum appears mixed with water has been used since 1498, notably for medical purposes.
Oil sands have been mined since the 18th century. In Wietze in lower Saxony, natural asphalt/bitumen has been explored since the 18th century. Both in Pechelbronn as in the coal industry dominated the petroleum technologies. Chemist James Young noticed a natural petroleum seepage in the Riddings colliery at Alfreton, Derbyshire from which he distilled a light thin oil suitable for use as lamp oil, at the same time obtaining a more viscous oil suitable for lubricating machinery. In 1848, Young set up a small business refining the crude oil. Young succeeded, by distilling cannel coal at a low heat, in creating a fluid resembling petroleum, which when treated in the same way as the seep oil gave similar products. Young found that by sl
Fellow of the Royal Society
Fellowship of the Royal Society is an award granted to individuals that the Royal Society of London judges to have made a'substantial contribution to the improvement of natural knowledge, including mathematics, engineering science and medical science'. Fellowship of the Society, the oldest scientific academy in continuous existence, is a significant honour, awarded to many eminent scientists from history including Isaac Newton, Charles Darwin, Michael Faraday, Ernest Rutherford, Srinivasa Ramanujan, Albert Einstein, Winston Churchill, Subrahmanyan Chandrasekhar, Dorothy Hodgkin, Alan Turing and Francis Crick. More fellowship has been awarded to Stephen Hawking, Tim Hunt, Elizabeth Blackburn, Tim Berners-Lee, Venkatraman Ramakrishnan, Atta-ur Rahman, Andre Geim, James Dyson, Ajay Kumar Sood, Subhash Khot, Elon Musk and around 8,000 others in total, including over 280 Nobel Laureates since 1900; as of October 2018, there are 1689 living Fellows and Honorary Members, of which over 60 are Nobel Laureates.
Fellowship of the Royal Society has been described by The Guardian newspaper as “the equivalent of a lifetime achievement Oscar” with several institutions celebrating their announcement each year. Up to 60 new Fellows and foreign members are elected annually in late April or early May, from a pool of around 700 proposed candidates each year. New Fellows can only be nominated by existing Fellows for one of the fellowships described below: Every year, up to 52 new Fellows are elected from the United Kingdom and the Commonwealth of Nations which make up around 90% of the society; each candidate is considered on their merits and can be proposed from any sector of the scientific community. Fellows are elected for life on the basis of excellence in science and are entitled to use the post-nominal letters FRS. See Category:Fellows of the Royal Society and Category:Female Fellows of the Royal Society; every year, Fellows elect up to ten new Foreign Members. Like Fellows, Foreign Members are elected for life through peer review on the basis of excellence in science.
As of 2016 there are around 165 Foreign Members, who are entitled to use the post-nominal ForMemRS. See Category:Foreign Members of the Royal Society. Honorary Fellowship is an honorary academic title awarded to candidates who have given distinguished service to the cause of science, but do not have the kind of scientific achievements required of Fellows or Foreign Members. Honorary Fellows include Bill Bryson, Melvyn Bragg, Robin Saxby, David Sainsbury, Baron Sainsbury of Turville and Onora O'Neill. Honorary Fellows are entitled to use the post nominal letters FRS. Others including John Maddox, Patrick Moore and Lisa Jardine were elected as honorary fellows, see Category:Honorary Fellows of the Royal Society. Statute 12 is a legacy mechanism for electing members before official honorary membership existed in 1997. Fellows elected under statute 12 include 4th Earl of Selborne. Prime Ministers of the United Kingdom such as Margaret Thatcher, Neville Chamberlain,Ramsay Macdonald and H. H. Asquith were elected under statute 12, see Category:Fellows of the Royal Society.
The Council of the Royal Society can recommend members of the British Royal Family for election as Royal Fellows of the Royal Society. As of 2016 there are five royal fellows: Charles, Prince of Wales elected 1978 Anne, Princess Royal elected 1987 Prince Edward, Duke of Kent elected 1990 Prince William, Duke of Cambridge elected 2009 Prince Andrew, Duke of York elected 2013Her Majesty the Queen, Elizabeth II is not a Royal Fellow, but provides her patronage to the Society as all reigning British monarchs have done since Charles II of England. Prince Philip, Duke of Edinburgh was elected under statute 12, not as a Royal Fellow; the election of new fellows is announced annually in May, after their nomination and a period of peer-reviewed selection. Each candidate for Fellowship or Foreign Membership is nominated by two Fellows of the Royal Society, who sign a certificate of proposal. Nominations required at least five fellows to support each nomination by the proposer, criticised for establishing an old-boy network and elitist gentlemen's club.
The certificate of election includes a statement of the principal grounds on which the proposal is being made. There is no limit on the number of nominations made each year. In 2015, there were 654 candidates for election as Fellows and 106 candidates for Foreign Membership; the Council of the Royal Society oversees the selection process and appoints 10 subject area committees, known as Sectional Committees, to recommend the strongest candidates for election to Fellowship. The final list of up to 52 Fellowship candidates and up to 10 Foreign Membership candidates is confirmed by the Council in April and a secret ballot of Fellows is held at a meeting in May. A candidate is elected if she secures two-thirds of votes of those Fellows present and voting. A maximum of 18 Fellowships can be allocated to candidates from Physical Sciences and Biological Sciences. A further maximum of 6 can be ‘Honorary’, ‘General’ or ‘Royal’ Fellows. Nominations for Fellowship are peer reviewed by sectional committees, each with 15 members and a chair.
Members of the 10 sectional committees change every 3 years to mitigate in-group bias, each group covers different
World War II
World War II known as the Second World War, was a global war that lasted from 1939 to 1945. The vast majority of the world's countries—including all the great powers—eventually formed two opposing military alliances: the Allies and the Axis. A state of total war emerged, directly involving more than 100 million people from over 30 countries; the major participants threw their entire economic and scientific capabilities behind the war effort, blurring the distinction between civilian and military resources. World War II was the deadliest conflict in human history, marked by 50 to 85 million fatalities, most of whom were civilians in the Soviet Union and China, it included massacres, the genocide of the Holocaust, strategic bombing, premeditated death from starvation and disease, the only use of nuclear weapons in war. Japan, which aimed to dominate Asia and the Pacific, was at war with China by 1937, though neither side had declared war on the other. World War II is said to have begun on 1 September 1939, with the invasion of Poland by Germany and subsequent declarations of war on Germany by France and the United Kingdom.
From late 1939 to early 1941, in a series of campaigns and treaties, Germany conquered or controlled much of continental Europe, formed the Axis alliance with Italy and Japan. Under the Molotov–Ribbentrop Pact of August 1939, Germany and the Soviet Union partitioned and annexed territories of their European neighbours, Finland and the Baltic states. Following the onset of campaigns in North Africa and East Africa, the fall of France in mid 1940, the war continued between the European Axis powers and the British Empire. War in the Balkans, the aerial Battle of Britain, the Blitz, the long Battle of the Atlantic followed. On 22 June 1941, the European Axis powers launched an invasion of the Soviet Union, opening the largest land theatre of war in history; this Eastern Front trapped most crucially the German Wehrmacht, into a war of attrition. In December 1941, Japan launched a surprise attack on the United States as well as European colonies in the Pacific. Following an immediate U. S. declaration of war against Japan, supported by one from Great Britain, the European Axis powers declared war on the U.
S. in solidarity with their Japanese ally. Rapid Japanese conquests over much of the Western Pacific ensued, perceived by many in Asia as liberation from Western dominance and resulting in the support of several armies from defeated territories; the Axis advance in the Pacific halted in 1942. Key setbacks in 1943, which included a series of German defeats on the Eastern Front, the Allied invasions of Sicily and Italy, Allied victories in the Pacific, cost the Axis its initiative and forced it into strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France, while the Soviet Union regained its territorial losses and turned toward Germany and its allies. During 1944 and 1945 the Japanese suffered major reverses in mainland Asia in Central China, South China and Burma, while the Allies crippled the Japanese Navy and captured key Western Pacific islands; the war in Europe concluded with an invasion of Germany by the Western Allies and the Soviet Union, culminating in the capture of Berlin by Soviet troops, the suicide of Adolf Hitler and the German unconditional surrender on 8 May 1945.
Following the Potsdam Declaration by the Allies on 26 July 1945 and the refusal of Japan to surrender under its terms, the United States dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August respectively. With an invasion of the Japanese archipelago imminent, the possibility of additional atomic bombings, the Soviet entry into the war against Japan and its invasion of Manchuria, Japan announced its intention to surrender on 15 August 1945, cementing total victory in Asia for the Allies. Tribunals were set up by fiat by the Allies and war crimes trials were conducted in the wake of the war both against the Germans and the Japanese. World War II changed the political social structure of the globe; the United Nations was established to foster international co-operation and prevent future conflicts. The Soviet Union and United States emerged as rival superpowers, setting the stage for the nearly half-century long Cold War. In the wake of European devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia.
Most countries whose industries had been damaged moved towards economic expansion. Political integration in Europe, emerged as an effort to end pre-war enmities and create a common identity; the start of the war in Europe is held to be 1 September 1939, beginning with the German invasion of Poland. The dates for the beginning of war in the Pacific include the start of the Second Sino-Japanese War on 7 July 1937, or the Japanese invasion of Manchuria on 19 September 1931. Others follow the British historian A. J. P. Taylor, who held that the Sino-Japanese War and war in Europe and its colonies occurred and the two wars merged in 1941; this article uses the conventional dating. Other starting dates sometimes used for World War II include the Italian invasion of Abyssinia on 3 October 1935; the British historian Antony Beevor views the beginning of World War II as the Battles of Khalkhin Gol fought between Japan and the fo
Malaysian nationality law
Malaysian nationality law is the law of Malaysia that deals with citizenship and other forms of nationality. Nationality law is mentioned in the Constitution of Malaysia. Citizenship law was first implemented in several Malaysian states before the country achieved independence and sovereignty; the Straits Settlements, consisting of Penang, Malacca and Labuan, was the first entity to introduce nationality laws in the region. The Naturalization Act of 1867 stated that: any person, whilst residing in the Colony, may present a memorial to the Governor in Council, praying that the privileges of naturalisation may be conferred upon him, it provided that: such memorial shall state to the best of the knowledge and belief of the memorialist, his age, place of birth, place of residence, trade or occupation, the length of time during which he has resided within the Colony, that he is permanently settled in the Colony, or is residing within the same, with attempt to settle therein. The criteria to be a Malaysian citizen are: Every person born before Malaysia Day, a citizen of Malaysia by virtue of these provisionsEvery person who before Merdeka Day 1957, was a citizen of Malaysia by virtue of any of the provisions of the Federation of Malaya Agreement, 1948, whether by operation of law or otherwise Every person born within Malaysia on or after Merdeka Day and before October 1962 Every person born within Malaysia after September 1962, of whose, at least, one parent was at the time of the birth either a citizen or a permanent resident in Malaysia, or, not born a citizen of any other country Every person born outside Malaysia on or after Merdeka Day whose father was a citizen at the time of his birth and either was born in Malaysia or was at the time of the birth in service under the Government of Malaysia or of a State Every person born outside Malaysia on or after Merdeka Day whose father was a citizen at the time of the birth if the birth was, or is, within 1 year of its occurrence or within such longer period as in any particular case was or is allowed by the Malaysian Government, registered at a consulate of Malaysia or, if it occurred in Singapore, Brunei or North Borneo, registered with the Federal GovernmentEvery person born on or after Malaysia Day, having any of the qualifications specified belowEvery person born within Malaysia of whose parents one at least is at the time of the birth either a citizen or permanently resident in Malaysia and Every person born outside Malaysia whose father is at the time of the birth a citizen and either was born in Malaysia or is at the time of the birth in the service of the Federation or of a State and Every person born outside Malaysia whose father is at the time of the birth a citizen and whose birth is, within 1 year of its occurrence or within such longer period as the Malaysian Government may in any particular case allow, registered at a consulate of Malaysia or, if it occurs in Brunei or in a territory prescribed for this purpose by order of the Yang di-Pertuan Agong, registered with the Malaysian Government and Every person born in Singapore of whose parents one at least is at the time of the birth a citizen and, not born citizen otherwise than by virtue of this paragraph and Every person born within Malaysia, not born a citizen of any country otherwise than by virtue of this paragraph A person can become a citizen of Malaysia either by registration or naturalisation.
In cases by registration, where a person is by operation of law is a citizen but have yet to be registered, such person is entitled to citizenship upon application and be registered as a citizen of Malaysia. For cases by naturalisation, this refers to the process of admitting a person not a citizen of Malaysia to citizenship; this is subjected to the conditions of the Federal Government. Any person holding Malaysian citizenship is disallowed to hold any other country's citizenship. Malaysia does not allow dual citizenship; those applying for citizenship by registration must have "an elementary knowledge of the Malay language". Those applying to become naturalised citizens must have "an adequate knowledge of the Malay language" and have resided in the country for ten of the past twelve years, including the twelve months preceding the application; these requirements are set out by Part III of the Constitution. Permanent residency in the states of Sabah and Sarawak are distinct from the other 11 Malaysian states.
While Sabah and Sarawak each has autonomy in immigration affairs, permanent residents of Sabah and Sarawak are exempted from the immigration controls of their own states. A Malaysian citizen born to a Sabah or Sarawak permanent resident would have Sabah or Sarawak permanent residency, regardless of where the person was born. Birth in Sabah or Sarawak alone does not make a person a permanent resident unless one of his/her parents is a permanent resident. A person may become a Sabah or Sarawak permanent resident by obtaining Permanent Residence status issued by the respective state immigration departments; the permanent residency status of a person is indicated by a letter on his/her MyKad below the photo, with H for Sabahans, K for Sarawakians, none for Peninsular Malaysians. A similar scheme is used in Malaysian passports, differentiated by the letter prefix of the passport number:H for Sabahans, K for Sarawakians, A for Peninsular Malaysians. All Malaysian citizens are Commonwealth citizens and are
Chemistry is the scientific discipline involved with elements and compounds composed of atoms and ions: their composition, properties and the changes they undergo during a reaction with other substances. In the scope of its subject, chemistry occupies an intermediate position between physics and biology, it is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant chemistry, the formation of igneous rocks, how atmospheric ozone is formed and how environmental pollutants are degraded, the properties of the soil on the moon, how medications work, how to collect DNA evidence at a crime scene. Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are four types of chemical bonds: covalent bonds, in which compounds share one or more electron; the word chemistry comes from alchemy, which referred to an earlier set of practices that encompassed elements of chemistry, philosophy, astronomy and medicine.
It is seen as linked to the quest to turn lead or another common starting material into gold, though in ancient times the study encompassed many of the questions of modern chemistry being defined as the study of the composition of waters, growth, disembodying, drawing the spirits from bodies and bonding the spirits within bodies by the early 4th century Greek-Egyptian alchemist Zosimos. An alchemist was called a'chemist' in popular speech, the suffix "-ry" was added to this to describe the art of the chemist as "chemistry"; the modern word alchemy in turn is derived from the Arabic word al-kīmīā. In origin, the term is borrowed from the Greek χημία or χημεία; this may have Egyptian origins since al-kīmīā is derived from the Greek χημία, in turn derived from the word Kemet, the ancient name of Egypt in the Egyptian language. Alternately, al-kīmīā may derive from χημεία, meaning "cast together"; the current model of atomic structure is the quantum mechanical model. Traditional chemistry starts with the study of elementary particles, molecules, metals and other aggregates of matter.
This matter can be studied in isolation or in combination. The interactions and transformations that are studied in chemistry are the result of interactions between atoms, leading to rearrangements of the chemical bonds which hold atoms together; such behaviors are studied in a chemistry laboratory. The chemistry laboratory stereotypically uses various forms of laboratory glassware; however glassware is not central to chemistry, a great deal of experimental chemistry is done without it. A chemical reaction is a transformation of some substances into one or more different substances; the basis of such a chemical transformation is the rearrangement of electrons in the chemical bonds between atoms. It can be symbolically depicted through a chemical equation, which involves atoms as subjects; the number of atoms on the left and the right in the equation for a chemical transformation is equal. The type of chemical reactions a substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws.
Energy and entropy considerations are invariably important in all chemical studies. Chemical substances are classified in terms of their structure, phase, as well as their chemical compositions, they can be analyzed using the tools of e.g. spectroscopy and chromatography. Scientists engaged in chemical research are known as chemists. Most chemists specialize in one or more sub-disciplines. Several concepts are essential for the study of chemistry; the particles that make up matter have rest mass as well – not all particles have rest mass, such as the photon. Matter can be a mixture of substances; the atom is the basic unit of chemistry. It consists of a dense core called the atomic nucleus surrounded by a space occupied by an electron cloud; the nucleus is made up of positively charged protons and uncharged neutrons, while the electron cloud consists of negatively charged electrons which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons.
The nucleus is dense. The atom is the smallest entity that can be envisaged to retain the chemical properties of the element, such as electronegativity, ionization potential, preferred oxidation state, coordination number, preferred types of bonds to form. A chemical element is a pure substance, composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol Z; the mass number is the sum of the number of neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same
Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a reduction process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions; the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in simple terms: Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. Reduction is a decrease in oxidation state by a molecule, atom, or ion; as an example, during the combustion of wood, oxygen from the air is reduced, gaining electrons from carbon, oxidized. Although oxidation reactions are associated with the formation of oxides from oxygen molecules, oxygen is not included in such reactions, as other chemical species can serve the same function; the reaction can occur slowly, as with the formation of rust, or more in the case of fire.
There are simple redox processes, such as the oxidation of carbon to yield carbon dioxide or the reduction of carbon by hydrogen to yield methane, more complex processes such as the oxidation of glucose in the human body. "Redox" is a portmanteau of the words "reduction" and "oxidation". The word oxidation implied reaction with oxygen to form an oxide, since dioxygen was the first recognized oxidizing agent; the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions. The meaning was generalized to include all processes involving loss of electrons; the word reduction referred to the loss in weight upon heating a metallic ore such as a metal oxide to extract the metal. In other words, ore was "reduced" to metal. Antoine Lavoisier showed. Scientists realized that the metal atom gains electrons in this process; the meaning of reduction became generalized to include all processes involving a gain of electrons. Though "reduction" seems counter-intuitive when speaking of the gain of electrons, it might help to think of reduction as the loss of oxygen, its historical meaning.
Since electrons are negatively charged, it is helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes when they occur at electrodes; these words are analogous to protonation and deprotonation, but they have not been adopted by chemists worldwide. The term "hydrogenation" could be used instead of reduction, since hydrogen is the reducing agent in a large number of reactions in organic chemistry and biochemistry. But, unlike oxidation, generalized beyond its root element, hydrogenation has maintained its specific connection to reactions that add hydrogen to another substance; the word "redox" was first used in 1928. The processes of oxidation and reduction occur and cannot happen independently of one another, similar to the acid–base reaction; the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction.
When writing half-reactions, the gained or lost electrons are included explicitly in order that the half-reaction be balanced with respect to electric charge. Though sufficient for many purposes, these general descriptions are not correct. Although oxidation and reduction properly refer to a change in oxidation state — the actual transfer of electrons may never occur; the oxidation state of an atom is the fictitious charge that an atom would have if all bonds between atoms of different elements were 100% ionic. Thus, oxidation is best defined as an increase in oxidation state, reduction as a decrease in oxidation state. In practice, the transfer of electrons will always cause a change in oxidation state, but there are many reactions that are classed as "redox" though no electron transfer occurs. In redox processes, the reductant transfers electrons to the oxidant. Thus, in the reaction, the reductant or reducing agent loses electrons and is oxidized, the oxidant or oxidizing agent gains electrons and is reduced.
The pair of an oxidizing and reducing agent that are involved in a particular reaction is called a redox pair. A redox couple is a reducing species and its corresponding oxidizing form, e.g. Fe2+/Fe3+ Substances that have the ability to oxidize other substances are said to be oxidative or oxidizing and are known as oxidizing agents, oxidants, or oxidizers; that is, the oxidant removes electrons from another substance, is thus itself reduced. And, because it "accepts" electrons, the oxidizing agent is called an electron acceptor. Oxygen is the quintessential oxidizer. Oxidants are chemical substances with elements in high oxidation states, or else electronegative elements that can gain extra electrons by oxidizing another substance. Substances that have the ability to reduce other substances are said to be reductive or reducing and are known as