CHEMISTRY GLOSSARY

electrolytes    →   elektroliti

Electrolytes are substances which, when melted or dissolved in water, conduct electric current. By melting or dissolving they are dissociated into electrically charged particles (ions) which are able to conduct electric current. By passing of electric current the transfer of matter occurs. Positively charged particles (cations) travel towards the negative pole (the cathode) and negatively charged particles (the anions) travel towards the positive pole (the anode). Liquid metals, in which the conduction is by free electrons, are not usually regarded as electrolytes. Solid conductors of ions, as in the sodium-sulphur cell, are also known as electrolytes. Depending upon how it conducts electric current, matter can be divided into strong electrolytes, weak electrolytes and nonconductors.

electroplating    →   galvaniziranje

Electroplating (also called electrodeposition) is the deposition of a metallic coating onto an object by putting a negative charge onto the object and immersing it into a solution which contains a salt of the metal to be deposited. The metallic ions of the salt carry a positive charge and are attracted to the part. When they reach it, the negatively charged part provides the electrons to reduce the positively charged ions to metallic form.

Typically, a brass or nickel object is coated with a layer of silver by making use of electrolysis of a silver solution, using the object to be coated as the cathode. The anode consist of pure silver, and the cathode is the object to be plated. The electrolyte is a mixure of silver nitrate with potassium cyanide. The reactions are:

The cyanide ensures a low concentration of silver ions, a condition for providing the best plating results.

seaborgium    →   seaborgij

Seaborgium was discovered by workers at the Nuclear Institute at Dubna (USSR) and by workers at the University of California, Berkeley (USA) in 1974. Named in honour of Glenn T. Seaborg, American nuclear chemist and Nobel prize winner. It is synthetic radioactive metal. Seaborgium was made by bombarding californium-249 with oxygen-18.

erbium    →   erbij

Erbium was discovered by Carl Gustaf Mosander (Sweden) in 1843. Named after Ytterby, a village in Sweden. It is soft, malleable, silvery metal. Reacts slowly with water. Dissolves in acids. Metal ignites and burns readily. Erbium is found with other heavier rare earths in xenotime and euxenite. Erbium oxide is used in ceramics to obtain a pink glaze. Also a few uses in the nuclear industry and as an alloying agent for other exotic metals.

europium    →   europij

Europium was discovered by Eugene Demarcay (France) in 1896. Named for the continent of Europe. It is soft, silvery-white metal. Extremely reactive with oxygen and water. Europium is obtained from monazite sand, which is a mixture of phosphates of calcium, thorium, cerium and most other rare earths. Used with yttrium oxide to make red phosphors for colour televisions.

face-centered cubic lattice    →   plošno centrirana kubična rešetka

Face-centered cubic lattice (fcc or cubic-F), like all lattices, has lattice points at the eight corners of the unit cell plus additional points at the centers of each face of the unit cell. It has unit cell vectors a =b =c and interaxial angles α=β=γ=90°.

The simplest crystal structures are those in which there is only a single atom at each lattice point. In the fcc structures the spheres fill 74 % of the volume. The number of atoms in a unit cell is four (8×1/8 + 6×1/2 = 4). There are 26 metals that have the fcc lattice.

Fehling’s test    →   Fehlingova otopina

Fehling’s test is a chemical test to detect reducing sugars and aldehydes in a solution, devised by the German chemist Hermann Christian von Fehling (1812-1885). Fehling’s solution consists of Fehling’s A (copper(II) sulphate solution) and Fehling’s B (sodium tartarate solution), equal amounts of which are added to the test solution. After boiling, a positive result is indicated by the formation of a brick-red precipitate of copper(I) oxide. Methanal, being a strong reducing agent, also produces copper metal; ketones do not react. The test is now rarely used, having been replaced by Benedict’s test.

selenide    →   selenid

Selenides are compounds having the structure R-Se-R (R not equal to H). They are thus selenium analogues of ethers. Also used for metal salts of H₂Se.

semimetal    →   metaloid

See Metalloid

soldering    →   lemljenje

Soldering is a process of joining metallic surfaces with solder without melting the base material.