No Added Chemicals

The International Year of Chemistry 2011 ( IYC 2011) is a worldwide celebration of the achievements of chemistry and its contributions to the well-being of humankind. Under the unifying theme “ Chemistry—our life, our future ,” IYC 2011 will offer a range of interactive, entertaining, and educational activities for all ages. The Year of Chemistry is intended to reach across the globe, with opportunities for public participation at the local, regional, and national level. The goals of IYC2011 are to increase the public appreciation of chemistry in meeting world needs, to encourage interest in chemistry among young people, and to generate enthusiasm for the creative future of chemistry. The year 2011 will coincide with the 100th anniversary of the Nobel Prize awarded to Madame Marie Curie—an opportunity to celebrate the contributions of women to science. The year will also be the 100th anniversary of the founding of the International Association of Chemical Societies, pr...

Aufbau Principle The Aufbau principle (from the German Aufbau meaning "building up, construction": also Aufbau rule or building-up principle ) is used to determine the electron configuration of an atom , molecule or ion . The principle postulates a hypothetical process in which an atom is "built up" by progressively adding electrons. As they are added, they assume their most stable conditions ( electron orbitals ) with respect to the nucleus and those electrons already there.

A clathrate, clathrate compound or cage compound is a chemical substance consisting of a lattice of one type of molecule trapping and containing a second type of molecule. The name clathrate complex used to refer only to the inclusion complex of hydroquinone, but recently it has been adopted for many other weak composites which consist of a host molecule (forming the basic frame) and a guest molecule (held in the host molecule by inter-molecular interaction). Clathrates are also called host-guest complexes, inclusion compounds, and adducts (chiefly in the case of urea and thiourea). They used to be called molecular compounds. A clathrate hydrate, in particular, is a special type of gas hydrate in which a lattice of water molecules encloses molecules of a trapped gas. Large amounts of methane naturally frozen in this form have been discovered both in permafrost formations and under the ocean sea-bed. Researchers have begun to investigate silicon and germanium clathrates for possible...

The Collision theory , proposed by Max Trautz and William Lewis in 1916 and 1918, qualitatively explains how chemical reactions occur and why reaction rates differ for different reactions. This theory is based on the idea that reactant particles must collide for a reaction to occur, but only a certain fraction of the total collisions have the energy to connect effectively and cause the reactants to transform into products. This is because only a portion of the molecules have enough energy and the right orientation (or "angle") at the moment of impact to break any existing bonds and form new ones. The minimal amount of energy needed for this to occur is known as activation energy . Particles from different elements react with each other by releasing activation energy as they hit each other. If the elements react with each other, the collision is called successful, but if the concentration of at least one of the elements is too low, there will be fewer particles for the oth...

The idea to organize the International Chemistry Olympiad (IChO) was born in the former Czechoslovakia. The political situation in Czechoslovakia in the spring of 1968 was very tumultuous. Under new leaders the country was in an economic reform. Groups of intellectuals strove after a “socialism with a human face”. There was a smell of independence in the air. The people were full of activities, they wanted more contacts with other countries. One of the new ideas was to organize an International Chemical Olympiad (this was the first name for this competition). In 1968 the Chemistry Olympiad (ChO) was a part of a secondary school system already in all countries of the Soviet block. The ChO in the Soviet Union was a model for all other countries. This was a basis on which the idea of IChO was built. The teachers in the countries were already acquainted with the competition and its firm system (from the school round to the national round) was worked out. The Ministry of Education of the...

Valence shell electron pair repulsion (VSEPR) theory is a model in chemistry used to predict the shape of individual molecules based upon the extent of electron-pair electrostatic repulsion. It is also named Gillespie - Nyholm theory after its two main developers. The acronym "VSEPR" is sometimes pronounced "vesper" for ease of pronunciation.