CHEMISTRY GLOSSARY

lanthanides    →   lantanoidi

Lanthanides (lanthanons, lanthanoids or rare-earth elements) are a series of fourteen elements in the periodic table, generally considered to range in proton number from cerium to lutetium inclusive. It was convenient to divide these elements into the cerium group or light earth: cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu); and the yttrium group or heavy earths: gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) i lutetium (Lu). The position of lanthanum is somewhat equivocal and, although not itself a lanthanide, it is often included with them for comparative purpose. The lanthanides are sometimes simply called the rare earths. Apart from unstable Pm, the lanthanides are actually not rare. Cerium is the 26. most abundant of all elements, 5 times as abundant as Pb. All are silvery very reactive metals.

lanthanides contraction    →   kontrakcija lantanoida

Lanthanides contraction is a reduction of metal and ion diameters from lanthanum to lutetium and it is caused by a core charge growth inside the same shell. Elements which in the periodic system of elements come after lanthanides have, because of lanthanides contraction, smaller diameter than they should have according to their position in the periodic system of elements.

rare earth elements    →   elementi rijetkih zemalja

Rare earth elements (metals) are the elements scandium (Sc), yttrium (Y), and the lanthanides (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu). These elements got their name from the fact that chemists first isolated them in their oxide forms. These oxides somewhat resemble calcium, magnesium and aluminium oxides, sometimes called common earths. Do you want to know more?

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.