CHEMISTRY GLOSSARY

thorium    →   torij

Thorium was discovered by Jöns Jakob Berzelius (Sweden) in 1828. Named after Thor, the mythological Scandinavian god of war. It is heavy, grey, soft, malleable, ductile, radioactive metal. Tarnishes in air; reacts with water. Reacts violently with oxidants. Thorium is found in various minerals like monazite and thorite. Used in making strong alloys. Also in ultraviolet photoelectric cells. It is a common ingredient in high-quality lenses. Bombarded with neutrons make uranium-233, a nuclear fuel.

transition metal    →   prijelazni element

This group of metals is distinguished from other metals not by their physical properties, but by their electronic structure. Transition metals are elements characterized by a partially filled d subshell. The First Transition Series comprises scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni) and copper (Cu). The Second and Third Transition Series include the lanthanides and actinides, respectively.

The transition metals are noted for their variability in oxidation state. Thus, manganese has two electrons in its outside shell and five electrons in the next shell down, and exhibits oxidation states of +1, +2, +3, +4, +5, +6, and +7.

They are also characterised by the fact that well into the series, going from left to right, the properties of the succeeding metals do not differ greatly from the preceding ones.

wavenumber    →   valni broj

Wavenumber is the number of wave cycles per unit distance.

There are unfortunately two different definitions of the wavenumber.

Wavenumber, k, is most frequently defined as

with wavelength λ, phase velocity of wave v_p, and angular frequency ω.

Less frequently it is defined simply as

One must be careful to note which definition is in use. Wavenumbers are used extensively in infrared spectroscopy, and usually have units of cm^-1.

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.

X-rays    →   X-zrake

X-rays are electromagnetic radiation of shorter wavelength than ultraviolet radiation (10^-11 m to 10^-9 m or 0.01 nm to 1 nm) produced by bombardment of atoms by high-quantum-energy particles. X-rays can pass through many forms of matter and they are therefore used medically and industrially to examine the internal structure.

yttrium    →   itrij

Yttrium was discovered by Carl Gustaf Mosander (Sweden) in 1843. Named after Ytterby, a village in Sweden. It is silvery, ductile, fairly reactive metal. Exposed surfaces form oxide film. Easily combustible, reacts with oxygen in water to release hydrogen. Yttrium is found in minerals such as monazite, xenotime and yttria. Combined with europium to make red phosphors for colour TV’s. Yttrium oxide and iron oxide combine to form a crystal garnet used in radar.