CHEMISTRY GLOSSARY

beta particle    →   beta-čestica

Beta particle is a charged particle emitted from a radioactive atomic nucleus either natural or manufactured. The energies of beta particles range from 0 MeV to 4 MeV. They carry a single charge; if this is negative, the particle is identical with an electron; if positive, it is a positron.

An unstable atomic nucleus changes into a nucleus of the same mass number but different proton number with the emission of an electron and an antineutrino (or a positron and a neutrino)

chlorinity    →   klorinitet

Originally chlorinity (symbol Cl) was defined as the weight of chlorine in grams per kilogram of seawater after the bromides and iodides had been replaced by chlorides. To make the definition independent of atomic weights, chlorinity is now defined as 0.3285233 times the weight of silver equivalent to all the halides.

The Mohr-Knudsen titration method served oceanographers for more than 60 years to determine salinity from chlorinity. This modification of the Mohr method uses special volumetric glassware calibrated directly in chlorinity units. The Mohr method uses potassium chromate (K₂CrO₄) as an indicator in the titration of chloride ions chloride (plus a small amount of bromide and iodide) with a silver nitrate (AgNO₃) standard solution.

The other halides present are similarly precipitated.

A problem in the Mohr titration was that silver nitrate is not well suited for a primary standard. The Danish physicist Martin Knudsen (1871-1949) suggested that a standard seawater (Eau de mer Normale or Copenhagen Normal Water) be created and distributed to oceanographic laboratories throughout the world. This water was then used to standardize the silver nitrate solutions. In this way all chlorinity determinations were referred to one and the same standard which gave great internal consistency.

The relationship between chlorinity Cl and salinity S as set forth in Knudsen's tables is

In 1962, however, a better expression for the relationship between total dissolved salts and chlorinity was found to be

curium    →   kurij

Curium was discovered by Glenn T. Seaborg, Ralph A. James and Albert Ghiorso (USA) in 1944. Named in honour of Pierre and Marie Curie. It is silvery, malleable, synthetic radioactive metal. So radioactive it glows in the dark. Curium was made by bombarding plutonium with helium ions.

einsteinium    →   einsteinij

Einsteinium was discovered by Albert Ghiorso (USA) in 1952. Named in honour of Albert Einstein (1879-1955). It is synthetic radioactive metal. Einsteinium was made by bombarding uranium with neutrons.

fermium    →   fermij

Fermium was discovered by Albert Ghiorso (USA) in 1953. Named in honour of Enrico Fermi. It is synthetic radioactive metal. Fermium was produced by bombarding lighter transuranium elements with still lighter particles or by neutron capture.

Curie    →   Curie

Maria Sklodowska-Curie (1867-1934) Polish-born French chemist who went to Paris in 1891. She married the physicist Pierre Curie (1859-1906) in 1985 and soon began work on seeking radioactive elements other than uranium in pitchblende (to account for its unexpectedly high radioactivity). By 1898 she had discovered radium and polonium although it took her years to purify them. In 1903 the Curies shared the Nobel Prize for physics with Henri Becquerel, who had discovered radioactivity.

darmstadtium    →   darmstadtij

Darmstadtium was discovered by S. Hofmann et al. collaboration at the Heavy Ion Research Laboratory (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany in November 1994. The title honours the Laboratory for Heavy Ion Research (called GSI) in Darmstadt, Germany, where the substance was first made. It is synthetic radioactive metal. The fusion-evaporation reaction using a ⁶²Ni beam on an isotopically enriched ²⁰⁸Pb target produced four chains of alpha-emitting nuclides following the presumed formation of ²⁶⁹110 + ¹n.

decay series    →   raspadni niz

Decay series is a series of decay in which radioactive element is decomposed in different elements until it produces one stable atom.

dubnium    →   dubnij

Dubnium was discovered by workers at the Nuclear Institute at Dubna (USSR) and by workers at the University of California, Berkeley (USA) in 1967. The origin of the name dubnium is the Joint Nuclear Institute at Dubna, Russia, an institute heavily involved in the search for heavy elements. It is synthetic radioactive metal. Dubnium was made by bombarding californium-249 with a beam of nitrogen-15 ions. There are now five known isotopes of dubnium. The longest-lived is dubnium-262, with a half-life of 34 seconds.

francium    →   francij

Francium was discovered by Marguerite Perey (France) in 1939. Named for France, the nation of its discovery. It is highly rare and unstable, radioactive metal. Chemical properties similar to cesium. Francium is formed by decay of actinium. Produced by bombarding radium or astatine with neutrons. Since its isotopes have such short half-lives there are no commercially significant compounds of francium.