CHEMISTRY GLOSSARY

relative molecular mass    →   relativna molekularna masa

Relative molecular mass (M_r) is the ratio of the average mass per molecule or specified entity of a substance to 1/12 of the mass of nuclide ¹²C. Also called molecular weight. It is equal to the sum of the relative atomic masses of all the atoms that comprise a molecule. For example

M_r(H₂SO₄) = 2·A_r(H) + A_r(S) + 4·A_r(O)

= 2·1.0079 + 32.066 + 4·15.999

= 2.0158 + 32.066 + 63.996

= 98.078

thallium    →   talij

Thallium was discovered by Sir William Crookes (England) in 1861. The origin of the name comes from the Greek word thallos meaning green twig or green shoot. It is soft grey metal that looks like lead. Tarnishes in moist air. Reacts in heated moist air and in acids. Compounds highly toxic by inhalation or ingestion. Cumulative effects. Thallium is found in iron pyrites. Also in crookesite, hutchinsonite and lorandite. Most is recovered from the by-products of lead and zinc refining. Its compounds are used in rat and ant poisons. Also for detecting infrared radiation.

ununbium    →   ununbij

Ununbium was discovered by S. Hofmann et al. collaboration at the Heavy Ion Research Laboratory (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany in February 1996. The new element has not yet been officially named, but it is known as ununbium, according to the system designated by the IUPAC for naming new elements. It is synthetic radioactive metal. Using the electromagnetic velocity filter SHIP, fusion-like residues of the reaction of ⁷⁰Zn with enriched ²⁰⁸Pb targets were measured. Two chains of localized alpha-emitters were identified as originating with ²⁷⁷112 + ¹n.

ununquadium    →   ununkvadij

The discovery of ununquadium was reported informally in January 1999 following experiments towards the end of December 1998 involving scientists at Dubna (Joint Institute for Nuclear Research) in Russia and the Lawrence Livermore National Laboratory, USA. The new element has not yet been officially named, but it is known as ununquadium, according to the system designated by the IUPAC for naming new elements. It is synthetic radioactive metal. Only few atoms of element 114 (²⁸⁹114) has ever been made (through a nuclear reaction involving fusing a calcium atom with a plutonium atom) isolation of an observable quantity has never been achieved.

unununium    →   unununij

Unununium was discovered by S. Hofmann et al. collaboration at the Heavy Ion Research Laboratory (Gesellschaft für Schwerionenforschung, GSI) in Darmstadt, Germany in December 1994. The new element has not yet been officially named, but it is known as unununium, according to the system designated by the IUPAC for naming new elements. It is synthetic radioactive metal. In bombardments of ²⁰⁹Bi targets with ⁶⁴Ni using the velocity selector SHIP facility to discriminate in favor of the fused product, ²⁷²111 + ¹n, three sets of localized alpha-decay chains were observed with position-sensitive detectors.

work    →   rad

Work is the energy required to move an object against an opposing force. Work is usually expressed as a force times a displacement.

When a constant force F acts on a point-like object while the object moves through a displacement s, the force does work W on the object. If force and displacement are at a constant angle Θ to each other, the work is expressed by the scalar product of these two vectors:

When the force F on a point-like object is not constant that is, it depends on the position of the object, the work done by force while object moves from initial position with coordinates (x_i, y_i, z_i) to final position with coordinates (x_f, y_f, z_f)is given by expression:

Where F_x, F_y and F_z are scalar components of the force.

SI unit for work is joule (J); 1 J = 1 Nm = 1 kg m² s^-2. The electron-volt (eV) is commonly used in atomic and nuclear physics.