Group 16 / VIA; Chalcogenides

or Oxygen Group
Chalcogenides comes from Greek and means "ore formers". That is true enough since most ores are oxides or sulfides (plus a few carbonates). In less graecophilic times like right no (2011; Euro crisis, allegedly started by the Greeks but in truth by the American way of life), we call those elements "oxygen group"
Nothing needs to be said about the importance of oxygen (O). You can't do without for more then a few minutes, because oxidizing some of the slime inside you produces the energy needed to keep your entropy down and to get you going.
Sulfur (S), if disliked in steel, is an important element in many products, e.g. you car tires. Sulfuric acid (H2SO4 is produced in large quantities (100 Mio tons per year) since it is indispensable in the chemical industry.
Selenium (Se) is found inside copy machines and in some solar cells. Tellurium (Te) is also found in high-tech compounds but only in small quantities.
Polonium (Po) is radioactive, so forget it.
Table of Basic Data
 
Name
(German)		 Oxygen
Sauerstoff		 Sulfur
Schwefel		 Selenium
Selen 		Tellurium
Tellur 		Polonium
Polonium
Atomic number 8 16 34 52 84
Atomic mass [u] 16,0 32,07 78,96 127,6 208,98
Melting point [K] 54,75 386 490 722,7 527
Melting point [oC] -218,25 113 217 449,7 254
Melting point [oF] -360 235 422 842 489
Boiling point [K] -90,19 717,82 958,1 1263 1235
Density [g/cm3] 1,33 2,06 4,82 6,25 9,20
Ionization energy [eV] 13,62 10,36 9,75 9,01 8,42
Electronegativitiy 3,5 2,4 2,5 2,0 1,8
Atomic radius [pm] 60,4 104 116 143,2 167,5
Ionic radius [pm] 132 29 69 97 65
Oxidation numbers -2, -1 6, 4, 2, -2 6, 4, -2 6, 4, 2, -2 6, 4, 2
Lattice typ
Transformation temp. [oC]		 sc
 op
 r
 r
 op
Lattice constant [Å]
(a or c)		 ? ? ? 4,45
5,91		 ?
Young's - Modul us [GPa] ? ? ? 4,12 ?
Therm. expansion coefficient a
[10-6K-1]		 ? ? ? ? ?
 
In case of doubt all numbers are for room temperatures
fcc = face centered cubic; lattice const. = a
bcc = body centered cubic
sc = simple cubic
hp = simple hexagonal
hcp = hexagonal close packed; lattice constants a and c.
op = simple orthorhombic, monoclinic, triclinic
tp = simple tetragonal
dia = diamond structure
r = trigonal or rhomboedral trigonal

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© H. Föll (Iron, Steel and Swords script)