Group 7 / VIIB; Manganese Group

Manganese has enormous technical importance; most steels need to contain some of the stuff. Your run-of-the-mill battery probably contains manganese compounds, and there are many other uses. Fortunately, it's plentyful and cheap.
Rhenium is rare and mot much used. Technetium does not occur naturally bit must be made "technically" (hence the name) in a nuclear reactor.
 
Table of Basic Data
 
Name
(German) 		Manganese
Mangan 		Technetium
Technetium		 Rhenium
Rhenium
Atomic number 25 43 75
Atomic mass [u] 54,93805 98,9063 186,207
Melting point [K] 1517 2445 3453
Melting point [oC] 1244 2172 3180
Melting point [oF] 2.271 3942 5756
Boiling point [K] 2370 5303 5900
Density [g/cm3] 7,44 11,49 21,03
Ionization energy [eV] 7,435 7,28 7,88
Electro-negativitiy 1,6 1,4 1,5
Atomic radius [pm] 124 135,8 137,0
Ionic radius [pm] 91 56 60
Oxidation numbers 7 bis -3 7 bis -3 7 bis -3
Lattice typ
Transformation temp. [o C]		 bcc
1138
fcc
1095
sc		 hcp
-		 hcp
-
Lattice constant [Å]
(a or c)		 8,89 2,74
4,39		 2,76
4,46
Young's - Modul us [GPa] 208 407 461
Therm. expansion coefficient a
[10-6K-1]		 21 ? 6,8
 
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)