Chemistry Glossary

 

Absolute scale              See Kelvin scale.

 

Absolute zero               Absolute zero is the lowest temperature possible, at which all motion, even subatomic, ceases.  Absolute zero is theoretically - 273.15 C, 0 Kelvin, -459.67 F or 0 Rankine.

 

AcceleratorSee            Particle accelerator.

 

Acid                               An acid is a chemical compound which contains hydrogen and which releases hydrogen ions (H+).  See also Base and Neutral.

 

Alkali Earth Metals       Alkali earth metals is the group of six elements which make up the old IIA group (simply column 2 for IUPAC) of the periodic table.  These six elements, Beryllium, magnesium, calcium, strontium, barium, and radium, are all highly reactive with a        oxidation state of +2.

 

Alkali Metals                 Alkali metals is the group of six elements which make up part of the old IA group (simply column 1 for IUPAC) of the periodic table.  These six elements, lithium, sodium, potassium, rubidium, cesium, and francium, are all highly reactive and form singly-charged positive ions.  All elements in this group react violently with water to form hydroxides.

 

Alpha particle               An alpha particle is a subatomic particle consisting of two protons and two neutrons.  Alpha particles are emitted during the course of radioactive decay of some elements.

 

Alpha ray                       An alpha ray consists of a stream of Alpha particles.

 

Ångström unit               An Ångström is a measurement unit of length equal to one hundred-millionth (10^-8) of a centimeter.  Named after Anders Jonas Ångström (1814-1874).

 

Antielectrons                 See Positrons.

 

Antimatter                     Antimatter is matter which is a mirror image of normal matter, consisting of particles of opposite charge, spin, and/or magnetic polarity.  Once hypothetical  matter, antimatter can now be artificially created in minute quantities at the expenditure of huge amounts of energy.  In the future it is hoped that antimatter may be a viable source of energy, but today it requires more energy to produce than is created by its annihilation from contact with normal matter.

 

 

Antineutrino                   Antineutrinos are the antiparticle equivalent of neutrinos.

 

Antiparticles                  Antiparticles are mirror images of normal elementary particles.  See also Antimatter.

 

Antiprotons                   Antiprotons are the antiparticle equivalent of protons.

 

Atom                              An atom is the smallest whole unit of any element that cannot be subdivided any further by chemical means.  Once thought to be the smallest possible division of matter, hence Atom (from the Bible) for beginning building block of all things, the atom is now known to be further divisible into the subatomic particles by electrical means, which in turn are even further divisible.

 

Atomic number             The atomic number of an element corresponds to the number of protons in the nucleus of an atom.  When put in order of increasing atomic number, as does the periodic table, it can be seen that atomic number of an element is directly related to its Atomic weight.

 

Atomic weight               The atomic weight of an element is the weight of an element with reference to that of one atom of carbon-12, which has an atomic weight of 12 (hence a unit of atomic weight is equal to 1/12th the weight of a single atom of carbon-12.

 

Baryon                           Baryon is the class of subatomic particles of high weight.  This class includes the proton and the neutron.  See also Lepton and Meson.

 

Base                              A base is a chemical compound which reacts with an Acid in such a way as to produce a salt and water.

 

Beam                             A beam is radiation traveling in a specific direction.

 

Beta particle                 A beta particle is a fast-moving electron which has been emitted by a radioactive substance.

 

Beta ray                         A beta ray consists of a stream of Beta particles.

 

Binding energy             Binding energy is the required energy which to be applied to a nucleus to split it into its constituent protons and neutrons.

 

Bond                              A bond is the link between two or more atoms in a molecule that is caused by the transfer of electrons. See also Covalent bond and Ionic Bond.

 

Breeder reactor            A breeder reactor is a nuclear reactor which creates more fissionable material than it uses (hence the name breeder).

 

Catalyst                         A catalyst is a substance which is used to influence the rate of or start a chemical reaction without being permanently changed itself.

 

CERN                            CERN, the acronym for Center for European Nuclear Research.

 

Chemical equilibrium   Chemical equilibrium is the point in a chemical reaction in which all reaction has halted leaving some of the original material on affected.

 

Cohesion                      Cohesion is the force due to the attraction between molecules, which holds solids or liquids together.

 

Covalent Bond              A covalent bond is a bond in molecules in which an electron pair is shared between one two atoms.

 

Critical mass                Critical mass is the minimal mass of a fissionable material that is required to allow a chain reaction to be self-sustaining.

 

Critical temperature     Critical temperature is the temperature above which a gas cannot be kept as a liquid by pressure alone.

 

Cryogenics                   Cryogenics is the study of very low temperatures.

 

Cryostat                         A cryostat is a vessel which is used to maintain very low temperatures as required in cryogenics.

 

Crystal lattice Crystal lattice is a term used to describe a regular pattern of atoms in a crystalline solid.

 

Cyclotron                       A cyclotron is a particle accelerator in the shape of a circle or oval.

 

Density                          Density is mass per unit volume.

 

Electromagnetic           Electromagnetic interaction is the term used to interaction describe the transfer of photons between charged subatomic particles.  This interaction is infinite in range and has two possible outcomes.  1) If the two particles have like charges then the interaction produces a repulsion or 2) if the two particles have unlike charges then the interaction produces an attraction.

 

Electron                         An electron is a negatively charged subatomic particle, which orbits the nucleus of an atom.

 

Electronegativity           Electronegativity is a term which describes anything having a negative electric charge (attracting electrons).

 

Electropositivity            Electropositivity is a term which describes anything having a positive electric charge (releasing electrons ).

 

Fermion                         Fermion is a grouping of subatomic particles witch have a half-integer spin value.

 

Gluon                             Gluons are subatomic particles with a mass of zero.  They are responsible for strong interactions between quarks.  See also muon and Neutrino.

 

Graviton                         The gravitation is a hypothetical subatomic particle with a zero rest mass and electric charge.  It is the quantum of gravitational interaction.

 

Gram molecule             Gram molecule is the term given to molecular weight of a compound when expressed in grams.  Also called mole.

 

Hadron                          The term hadron applies to any subatomic particles which participate in the strong interaction.

 

Halogen Group             Halogen is the group of five elements which make up the old VIIB group (simply column 17 for IUPAC) of the periodic table.  These five elements, fluorine, chlorine, bromine, iodine, and astatine, are strongly electronegative and good oxidizing agents. Halogens also all emit an unpleasant odor and are corrosive to skin.

 

Heisenberg                   See Uncertainty principle. uncertainty principle

 

HIRL                               HIRL, the acronym for the Heavy Ion Research Laboratory.

 

Inert Gases                   The inert gases are the six elements which make up the old VIIB group (simply column 18 for IUPAC) of the periodic table.  These Six elements are helium, neon, argon, krypton, xenon, and radon.  Under normal conditions elements belonging to this group will not combine with other elements, hence the name inert.  They are also commonly referred to as the noble gases.

 

IUPAC                           IUPAC, the acronym for International Union for Pure and Applied Chemistry.

 

Kelvin scale                  The Kelvin scale is a scale of absolute temperature based on the Celsius temperature scale, that is one Kelvin unit is the same size as one Celsius degree.  The Kelvin scale starts at theoretical absolute zero, making 273.15 Kelvin equal to 0 C.  Note that Kelvin is both a temperature scale and a unit of temperature, therefore does not does not carry the degrees symbol. The Kelvin scale was once called the Absolute scale.

 

Lepton                           Lepton is the class of subatomic particles of low weight.  This class includes the electron, muon and neutrino. See also Baryon and Meson.

 

Linear accelerator        A linear accelerator is a particle accelerator in the form of a straight line.  See also Cyclotron.

 

Macromolecule             Macromolecule is the term used to describe a very large molecule.

 

Meson                                    Meson is the class which abides between the lepton and baryon classes of subatomic particles.  Compared to the other classes mesons are mediate in weight.

 

Metals                            The metals group consists of elements which generally exhibit proprieties such as being a good conductor of both electrical current and heat, having high density, malleable in solid state (all are solid at room temperature except mercury), and are electropositive.  There are some metals which are considered to be on a borderline between non-metals and metals, these elements includes, boron, silicon, germanium, arsenic, antimony, tellurium, and astatine.  These borderline elements are called metalloids and in the electronics field are called semiconductors and are widely used as doping agents in electronic devices such as transistors and diodes.

 

Mohs scale                   Mohs scale is the standard scale of hardness for materials.  The scale is as follows from softest to hardest:

 

                                       1       talc                  6          orthoclase

                                       2       gypsum           7          quartz

                                       3       calcite             8          topaz

                                       4       fluorite             9          corundum

                                       5       apatite            10        diamond

 

Molar                             Molar is the term used to describe a solution of liquid containing 1 gram molecule per liter.

 

Mole                               See Gram molecule.

 

Muon                              Muons short for mu-mesons, are subatomic particles once belonging to the meson group but later reclassified as belonging to the lepton group.  See also gluon and Neutrino and quark.

 

Neutral                           Neutral is the term used to describe a substance that is neither an acid nor a base and having a pH of exactly 7.

 

Neutrino                         A neutrino is a subatomic particle which as no charge and no rest mass belonging to the Fermion group.  Neutrinos and antineutrinos were hypothetical for a long time, 26 years to be exact, before they were detected because they are very difficult to detect.  To give an idea of just how hard they were to detect, try imagining a solid wall of lead that is 3,500 light years thick, that s the calculated distance an average neutrino would pass through lead before interacting with a particle, which must take place in order for the neutrino to be detected.  So if a neutrino is this hard to detect, just how did physicists detect it, the solution was simpler that you might think. 3,500 light years is the average distance, but many neutrinos would pass only a minute fraction of the distance, while many also would pass much further.  What was needed was a source of billions of antineutrinos and that source was already readily available, it was a U-235 powered reactor.  This common form of nuclear reactor normally produced roughly a billion billion antineutrinos per second.  Now the only problem left to be faced was building the device that would detect the interaction of the           antineutrinos.  The problem was finally solved in 1956, when Fredrick Reines and Clyde Cowan devised a device that did the job, confirming the existence of neutrinos once and for all.  The device was somewhat simple, it consisted of a tank of water and cadmium chloride with devices added to detect the gama rays which would be produced as an indirect result of the antineutrino if it existed. See also gluon and muon and quark.

 

Neutron                          The neutron is a subatomic particle in the baryon class that has no charge and if found in the nuclei of all atoms except hydrogen.  See also Electron and Proton.

 

Noble Gases                See Inert gases.

 

Non-metals                   The Non-metals is a small group of elements which can basically defined as element which are not metals and don t belong to any other major group.  The non-metals generally are brittle, low in density, electronegative, and poor at conducting electricity.  They may be gaseous, liquid, or solid at room temperature and are good oxidizing agents.

 

Nucleus                         The nucleus is the central mass of any atom.  It accounts for almost all total mass of the atom and consists of neutrons and protons, except for the element hydrogen, which has no neutrons. The nucleus carries a net overall positive charge.

 

Particle accelerator     A particle accelerator is a device which is used to accelerate subatomic particles to very high velocities, which in turn increases their energies.  The particle accelerator is used in particle physics research an without it many goals of physics research that have been accomplished today would not have been possible.  See also Cyclotron.

 

Photon                           A photon is a subatomic particle with zero mass and no electrical charge.  It has an infinite life and is its own antiparticle.

 

Positron                         Positrons are the antiparticle equivalent of electrons.

 

Proton                            A proton is a positively charged subatomic particle with a mass of about 1,836 times that of the electron.

 

Quark                             A quark is one of several known subatomic particles from which other subatomic particles are made up.  See also gluon, muon, and neutrino.

 

Rad                                A rad is unit of radiation dosage equal to an energy absorption of .00001 joules per gram.

 

Rankine                         The Rankine scale is a scale of absolute temperature based on the Fahrenheit temperature scale, that is one  Rankine is the same size as one Fahrenheit degree.   The Rankine scale starts at theoretical absolute zero, making 459.67  Rankine equal to 0 F.

 

Rare earth                     Rare earth elements, ironically, also called common earths, all have a valence of 3 and therefore exhibit similar chemical properties.  These elements make up the lanthanoid and actinoid, also called lanthanide and actinide respectively, series of elements.

 

Semiconductors           Semiconductors is a term used to describe elements or compounds which are on the borderline of being an electrical conductor and an electrical insulator.  When lined up end to end in crystal form some have a unique property of allowing electrical current to pass in only one direction, hence the basic concept of the diode.

 

Specific heat                Specific heat is the amount of heat energy required to raise 1 gram of a through one Celsius degree.

 

Stable                            The term stable is used to describe anything that shows little or no tendency to decompose.

 

Strong interaction         The term strong interaction is the term that describe the interaction which holds protons and neutrons together in the nucleus of an atom.

 

Synchrocyclotron          A synchrocyclotron is a modified cyclotron which allows for the changing of oscillation frequencies of the accelerator in order to allow for a particles decreasing mass as it as it reaches very high speeds.  See also Synchrotron and Particle accelerator.

 

Synchrotron                   A synchrotron is a modified synchrocyclotron which, as particles reach very high speeds, increases the magnetic fields which hold the particles or course.  Such an arrangement allows for higher possible energies in smaller accelerators.  See also Particle accelerator and cyclotron.

 

Synthetic elements       Synthetic elements are any elements which are know to exist but not naturally (man made).  Most synthetic elements are transuranic and are built up by the addition of subatomic particles, usually by using a particle accelerator.

 

Subatomic                    Subatomic is the term used to describe any particle that is smaller than an atom.

 

Tachyon                         Tachyons are hypothetical subatomic particles which are predicted to travel at a speed greater than light.

 

Tracer                            The term tracer refers to any substance, such as a radioactive isotope, which is identifiable and can be keep track of through the course of a biological or mechanical process.  Tracers are used extensively in the medical field.

 

Transition Metals          Transition metals form a group of elements based on the internal shell structure.  They all have their valence electrons residing in more that one shell unlike other metals, which have their valence electrons contained in a single shell.  Because they have their valence electrons in more than one shell, their oxidation states can vary wildly.

 

Uncertainty principle    The uncertainty principle is the principle that it is impossibility to know both the position and momentum of any subatomic particle simultaneously.  This is because subatomic particles are so small and have so little mass, that just the process of detecting them will alter one of these properties.  Also called the Heisenberg uncertainty principle after its founder, Werner K. Heisenberg (1901-1976).

 

Unstable                        The term unstable is used to describe anything that shows a tendency to decompose.

 

Vector boson                The vector boson is the virtual particle believed to be the cause of the weak force in nuclei.

 

Virtual particle              A virtual particle is a subatomic particle said to exist for an extremely short period of time when two other particles interact.

 

V particle                       The term  V particle refers to any of several known subatomic particles which have half-lives anywhere from 10-10 to 10-6 second and whose track observed in a cloud chamber resembles the shape of the letter V.

 

Weak force                   Weak force is the force in the nuclei of radioactive elements which control the rate of radioactive decay.

 

Weak interaction          The term weak interaction describes the interaction which regulates the way in which a neutron will shed an electron and a neutrino.  As the term implies, it is a weak interaction, though very weak would be more accurate at only about one hundred-billionth as intense as electromagnetic interaction.

 

W particles                    Any of four know subatomic particles which are together responsible for the weak interaction.  The first particle was photon, massless and its own antiparticle, the three other relatively large mass particles are the W+ (positive), the W- (negative), and the Z0 (neutral).Though they were all first predicted to exist in 1967 by Steven Weinberg, the second, Z0, was not discovered until 1984, and the other two, W+ and W-, were discovered a year later, all were reported discovered by Carlo Rubbia.

 

Xi particle                      The term Xi particle refers to one of two subatomic particles belonging to the baryon family with masses of 2,572 and 2,585 times that of the electron.

 

X-ray crystallography   X-ray crystallography is a method used to determine the atomic structure of a crystal.  This is accomplished by passing X-rays through a crystal and onto a x-ray sensitive film plate.

 

X-ray spectrometer      The X-ray spectrometer is a device used in chemical analysis.  A sample is bombarded with X-rays while the X-ray spectrum is measured to identify the sample (every element has its own unique X-ray spectrum).  The X-ray spectrum is measured by measuring its wavelengths.

 

Ylem                               Ylem is a the hypothetical matter believed to have been produced after the big bang and existed before the formation of normal matter (chemical elements).

 

Zwitterion                      A zwitterion is an ion which carries both a negative and a positive electrical charge forming neutral molecules