A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds. Two atoms of the same element bonded in a molecule do not form a chemical compound, since this would require two different elements. There are four types of compounds, depending on how the constituent atoms are held together: molecules held together by covalent bonds ionic compounds held together by ionic bonds intermetallic compounds held together by metallic bonds certain complexes held together by coordinate covalent bonds. A chemical formula specifies the number of atoms of each element in a compound molecule, using the standard abbreviations for the chemical elements and numerical subscripts. For example, a water molecule has formula H2O indicating two hydrogen atoms bonded to one oxygen atom. Many chemical compounds have a unique CAS number identifier assigned by the Chemical Abstracts Service. Globally, more than 350,000 chemicals compounds have been registered for use.
A compound can be converted to a different chemical composition by interaction with a second chemical compound via a chemical reaction. In this process, bonds between atoms are broken in both of the interacting compounds, new bonds formed. Any substance consisting of two or more different types of atoms in a fixed stoichiometric proportion can be termed a chemical compound, it follows from their being composed of fixed proportions of two or more types of atoms that chemical compounds can be converted, via chemical reaction, into compounds or substances each having fewer atoms. The ratio of each element in the compound is expressed in a ratio in its chemical formula. A chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using the standard abbreviations for the chemical elements, subscripts to indicate the number of atoms involved. For example, water is composed of two hydrogen atoms bonded to one oxygen atom: the chemical formula is H2O.
In the case of non-stoichiometric compounds, the proportions may be reproducible with regard to their preparation, give fixed proportions of their component elements, but proportions that are not integral. Chemical compounds have a unique and defined chemical structure held together in a defined spatial arrangement by chemical bonds. Chemical compounds can be molecular compounds held together by covalent bonds, salts held together by ionic bonds, intermetallic compounds held together by metallic bonds, or the subset of chemical complexes that are held together by coordinate covalent bonds. Pure chemical elements are not considered chemical compounds, failing the two or more atom requirement, though they consist of molecules composed of multiple atoms. Many chemical compounds have a unique numerical identifier assigned by the Chemical Abstracts Service: its CAS number. There is varying and sometimes inconsistent nomenclature differentiating substances, which include non-stoichiometric examples, from chemical compounds, which require the fixed ratios.
Many solid chemical substances—for example many silicate minerals—are chemical substances, but do not have simple formulae reflecting chemically bonding of elements to one another in fixed ratios. It may be argued that they are related to, rather than being chemical compounds, insofar as the variability in their compositions is due to either the presence of foreign elements trapped within the crystal structure of an otherwise known true chemical compound, or due to perturbations in structure relative to the known compound that arise because of an excess of deficit of the constituent elements at places in its structure. Other compounds regarded as chemically identical may have varying amounts of heavy or light isotopes of the constituent elements, which changes the ratio of elements by mass slightly. Compounds are held together through a variety of different types of bonding and forces; the differences in the types of bonds in compounds differ based on the types of elements present in the compound.
London dispersion forces are the weakest force of all intermolecular forces. They are temporary attractive forces that form when the electrons in two adjacent atoms are positioned so that they create a temporary dipole. Additionally, London dispersion forces are responsible for condensing non polar substances to liquids, to further freeze to a solid state dependent on how low the temperature of the environment is. A covalent bond known as a molecular bond, involves the sharing of electrons between two atoms; this type of bond occurs between elements that fall close to each other on the periodic table of elements, yet it is observed between some metals and nonmetals. This is due to the mechanism of this type of bond. Elements that fall close to each other on the periodic table tend to have similar electronegativities, which means they have a similar affinity for electrons. Since neither element has a stronger affinity to donate or gain electrons, it causes the elements to share electrons so both elements have a more stable octet.
Ionic bonding occurs when valence electrons are transferred between elements. Opposite to covalent bonding, this chemical bond creates two oppositely charged ions; the metals in ionic bonding lose their valence electrons, becoming a pos
Stewart Wallis is an advocate for a new economic system. He worked for Oxfam from 1992 to 2002, for which he was awarded an OBE. From 2003 to 2016, he was Executive Director of the New Economics Foundation. Wallis is the Chair for the Wellbeing Economy Alliance, a new major initiative to create a global new economy movement, he was born on the son of George and Jean Wallis. He took the tripos in Natural Sciences at Fitzwilliam College, Cambridge and, in 1976, obtained a MSc in Business and Economics from the London Business School. In 2016, Stewart was awarded an honorary Doctorate by Lancaster University, his business career began in marketing and sales with Rio Tinto Zinc from 1970 to 1974. He spent 1976 to 1983 with the World Bank in Washington, D. C. working on industrial and financial development in East Asia. He worked for Robinson Packaging in Derbyshire from 1983 to 1992, the last five as Managing Director, he joined Oxfam in 1992 as International Director with responsibility, for 2500 staff in seventy countries and for all Oxfam's policy, research and emergency work worldwide.
He was awarded the OBE for services to Oxfam in June 2002. Stewart was the Executive Director of the New Economics Foundation from November 2003 until December 2015, he was a Trustee of the Overseas Development Institute and Habitat for Humanity and a member of the UK Social Investment Task Force. He was vice chair of the World Economic Forum's Global Agenda Council on values and a Steward of their Inclusive Growth Initiative, he has since come out of retirement to voluntarily help to run the Wellbeing Economy Alliance. Other recent roles include the Chair of the Conservation Farming Trust, a Trustee of Devon Community Foundation. A Finer Future, by Hunter Lovins, John Fullerton, Stewart Wallis and Anders Wijkman, 2017. ISBN 9780865718982 Authored chapters on "A New Economic System Based on Core Human Values" in the book "Why Love Matters" and "Towards a Peaceful Economy" in the book "Peacefulness"-Both edited by Scherto Gill and David Cadman. Democracy and Capitalism, Lord Dahrendorf with commentaries by Professor Gerry Stoker, Ruth Lea, Stewart Wallis and Vince Cable MP, Hansard Society, 2006.
ISBN 978-0-900432-48-4. OldE conomicsNewEconomics.pdf In 1974, he married Dee Wallis who died in 1982. In 1987, he inherited a stepson, he has two with Dee and two with Mary Jane. Biography of Stewart Wallis on the website of the Wellbeing Economy Alliance: https://wellbeingeconomy.org/who-we-are Biography of Stewart Wallis on the website of the New Economics Foundation http://www.neweconomics.org/about/stewart-wallis Who's who entry Stewart Wallis interviewed by Edi Lush 28/01/2012 on YouTube
Ōmae Station is a railway station on the Agatsuma Line in Tsumagoi, Gunma Prefecture, operated by East Japan Railway Company. This station is 840.4m AMSL. Ōmae Station is a terminal station of the Agatsuma Line, is located 55.3 rail kilometers from the opposing terminus of the line at Shibukawa Station. Ōmae Station has a single side platform. The station is unattended. Ōmae Station was opened on 7 March 1971. The station was absorbed into the JR East network upon the privatization of the Japanese National Railways on 1 April 1987. Tsumagoi Onsen Agatsuma River Japan National Route 144 Japan National Route 406 JR East Station information