the production of thymoquinone from thymol and carvacrol
the production of thymoquinone from thymol and carvacrol
the production of thymoquinone from thymol and carvacrol
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CHAPTER 3<br />
TRANSITION METALS AND COORDINATION<br />
CHEMISTRY<br />
3.1. Definition <strong>and</strong> Physical Properties <strong>of</strong> Transition Metals<br />
The transition metals constitute groups 3 through 12 <strong>of</strong> <strong>the</strong> periodic table.<br />
They’re <strong>the</strong> elements which have partially filled d-shells <strong>and</strong> Zn, Cd <strong>and</strong> Hg are<br />
included even though <strong>the</strong>ir d-shells are entirely filled. The first row transition metals<br />
have <strong>the</strong> electronic configuration [Ar] 3d n 4s m where n is between1-10 <strong>and</strong> m is<br />
between1-2. The second row has <strong>the</strong> configuration [Kr] 4d 5s, <strong>and</strong> <strong>the</strong> third row have<br />
<strong>the</strong> configuration [Xe] 5d 6s (Solomons 1988).<br />
IIIB, IVB, VB, VIB, VIIB, VIII, IB, IIB elements <strong>of</strong> <strong>the</strong> periodic table are <strong>the</strong><br />
transition metals that are <strong>the</strong> most concern. As with all metals, <strong>the</strong> transition elements<br />
are both ductile <strong>and</strong> malleable, <strong>and</strong> conduct electricity <strong>and</strong> heat. Similarities occur<br />
within a period as well as within a group due to last electrons (Solomons 1988).<br />
The elements in <strong>the</strong> periodic table as shown in Figure 3.1 are <strong>of</strong>ten divided into<br />
four categories: (1) main group elements, (2) transition metals, (3) lanthanides, <strong>and</strong> (4)<br />
actinides. The main group elements include <strong>the</strong> active metals in <strong>the</strong> two columns on <strong>the</strong><br />
extreme left <strong>of</strong> <strong>the</strong> periodic table <strong>and</strong> <strong>the</strong> metals, semimetals, <strong>and</strong> nonmetals in <strong>the</strong> six<br />
columns on <strong>the</strong> far right. The transition metals are <strong>the</strong> metallic elements that serve as a<br />
bridge, or transition, between <strong>the</strong> two sides <strong>of</strong> <strong>the</strong> table. The lanthanides <strong>and</strong> <strong>the</strong><br />
actinides (f block elements) at <strong>the</strong> bottom <strong>of</strong> <strong>the</strong> table are sometimes known as <strong>the</strong> inner<br />
transition metals because <strong>the</strong>y have atomic numbers that fall between <strong>the</strong> first <strong>and</strong><br />
second elements in <strong>the</strong> last two rows <strong>of</strong> <strong>the</strong> transition metals. f-block elements are not<br />
traditionally treated as transition elements since f electrons do not affect bonding.<br />
Transition metals are more electronegative than <strong>the</strong> main group metals; <strong>the</strong>refore <strong>the</strong>y<br />
are more likely to form covalent compounds (Morrison 1992).<br />
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