Functional groupIn organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest of the molecule's composition. This enables systematic prediction of chemical reactions and behavior of chemical compounds and the design of chemical synthesis. The reactivity of a functional group can be modified by other functional groups nearby.
X-ray spectroscopyX-ray spectroscopy is a general term for several spectroscopic techniques for characterization of materials by using x-ray radiation. When an electron from the inner shell of an atom is excited by the energy of a photon, it moves to a higher energy level. When it returns to the low energy level, the energy which it previously gained by the excitation is emitted as a photon which has a wavelength that is characteristic for the element (there could be several characteristic wavelengths per element).
Perpetual motionPerpetual motion is the motion of bodies that continues forever in an unperturbed system. A perpetual motion machine is a hypothetical machine that can do work infinitely without an external energy source. This kind of machine is impossible, as it would violate either the first or second law of thermodynamics, or both. These laws of thermodynamics apply regardless of the size of the system.
Nuclear warfareNuclear warfare, also known as atomic warfare, is a military conflict or prepared political strategy that deploys nuclear weaponry. Nuclear weapons are weapons of mass destruction; in contrast to conventional warfare, nuclear warfare can produce destruction in a much shorter time and can have a long-lasting radiological result. A major nuclear exchange would likely have long-term effects, primarily from the fallout released, and could also lead to secondary effects, such as "nuclear winter", nuclear famine, and societal collapse.
Structural unitIn polymer chemistry, a structural unit is a building block of a polymer chain. It is the result of a monomer which has been polymerized into a long chain. There may be more than one structural unit in the repeat unit. When different monomers are polymerized, a copolymer is formed. It is a routine way of developing new properties for new materials. Consider the example of polyethylene terephthalate (PET or "polyester").
Nuclear weapons of the United KingdomIn 1952, the United Kingdom became the third country (after the United States and the Soviet Union) to develop and test nuclear weapons, and is one of the five nuclear-weapon states under the Treaty on the Non-Proliferation of Nuclear Weapons. The UK initiated a nuclear weapons programme, codenamed Tube Alloys, during the Second World War. At the Quebec Conference in August 1943, it was merged with the American Manhattan Project.
Reactivity seriesIn chemistry, a reactivity series (or activity series) is an empirical, calculated, and structurally analytical progression of a series of metals, arranged by their "reactivity" from highest to lowest. It is used to summarize information about the reactions of metals with acids and water, single displacement reactions and the extraction of metals from their ores.
Inductive effectIn chemistry, the inductive effect in a molecule is a local change in the electron density due to electron-withdrawing or electron-donating groups elsewhere in the molecule, resulting in a permanent dipole in a bond. It is present in a σ (sigma) bond, unlike the electromeric effect which is present in a π (pi) bond. The halogen atoms in an alkyl halide are electron withdrawing while the alkyl groups have electron donating tendencies.
