Bismuth was discovered by Claude Geoffroy (France) in 1753. The origin of the name comes from the German words Weisse Masse meaning white mass; now spelled wismut and bisemutum. It is hard, brittle, steel-grey metal with a pink tint. Stable in oxygen and water. Dissolves in concentrated nitric acid. Bismuth can be found free in nature and in minerals like bismuthine (Bi2S3) and in bismuth ochre (Bi2O3) Main use is in pharmaceuticals and low melting point alloys used as fuses.
Cadmium was discovered by Friedrich Strohmeyer (Germany) in 1817. The origin of the name comes from the Latin word cadmia meaning calamine (zinc carbonate, ZnCO3), or from the Greek word kadmeia with the same meaning. It is soft, malleable, blue-white metal. Tarnishes in air, soluble in acids, insoluble in alkalis. Boiling cadmium gives off a weird, yellow-colored vapour that is poisonous. Cadmium can cause a variety of health problems, including kidney failure and high blood pressure. Cadmium is obtained as a by product of zinc refining. The mayor use of cadmium is in electroplating of steel to protect it from corrosion. Also used to make nickel-cadmium batteries. The ability of cadmium to adsorb neutrons has made it of great importance in the design of nuclear reactors. Its compounds are found in paint pigments and a wide variety of intense colours.
Caesium was discovered by Robert Bunsen and Gustav Kirchhoff (Germany) in 1860. The origin of the name comes from the Latin word caesius meaning sky blue or heavenly blue. It is very soft, light grey, ductile metal. Reacts readily with oxygen. Reacts explosively with water. Caesium is found in pollucite [(Cs4Al4Si9O26)·H2O] and as trace in lepidolite. Used as a ’getter’ to remove air traces in vacuum and cathode-ray tubes. Also used in producing photoelectric devices and atomic clocks. Since it ionises readily, it is used as an ion rocket motor propellant.
Calcium was discovered by Sir Humphry Davy (England) in 1808. The origin of the name comes from the Latin word calix meaning lime. It is fairly hard, silvery-white metal. Exposed surfaces form oxides and nitrides. Reacts with water and oxygen. Occurs only in compounds. Calcium is obtained from minerals like chalk, limestone and marble. Pure metal is produced by replacing the calcium in lime (CaCO3) with aluminium in hot, low pressure retorts. Used by many forms of life to make shells and bones. Virtually no use for the pure metal, however two of its compounds are, lime (CaO) and gypsum (CaSO4), are in great demand by a number of industries.
Cyanide process is a method for separating a metal from an ore. Crushed ore is treated with cyanide ion to produce a soluble metal cyanide complex. The complex is washed out of the ore and reduced to metallic form using an active metal (usually zinc).
Dissolved substance is a solid, liquid or gas matter dissolved in a solvent. Depending upon the particle size of dissolved substance, solutions differ in properties and can be divided into real solutions (diameter of particles is smaller than 1 nm), colloid solutions (diameter of particles is from 1 nm to 200 nm) and suspensions (diameter of particles is greater than 200 nm).
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
Chromium was discovered by Louis-Nicholas Vauquelin (France) in 1797. The origin of the name comes from the Greek word chroma meaning colour. It is very hard, crystalline, steel-grey metal. The pure metal has a blue-white colour. It is hard, brittle and corrosion-resistant at normal temperatures. Hexavalent compounds toxic by skin contact. The most important chromium mineral is chromite [Fe,Mg(CrO4)]. Produced commercially by heating its ore in the presence of silicon or aluminium. Used to make stainless steel. It gives the colour to rubies and emeralds. Iron-nickel-chromium alloys in various percentages yield an incredible variety of the most important metals in modern technology.
Formaldehyde (methanal) is a colourless gas, HCHO; r.d. 0.815 (at -20 °C); m.p. -92 °C; b.p. -21 °C. It is the simplest aldehyde, made by the catalytic oxidation of methanol (500 °C; silver catalyst) by air. It forms two polymers: methanal trimer and polymethanal.
Generalic, Eni. "Koloidno srebro." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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Periodic Table