Chapter 2:- Transition Elements

B.sc 2nd year Book
Advance Inorganic Chemistry
(Page 2)

General Properties of Transitional Elements

In this chapter, let us discuss some general properties of transition elements. Nearly all transition metals are hard, ductile, malleable, and have high electrical and thermal conductivity. With the exceptions of Mn, Zn, Cd and Hg, they have one or more of the typical metal structures at ordinary temperatures. The members of a given transition series are so much different from one another than those of non-transition elements of the same period. The reason is that the electronic configurations of transition elements have been found to differ only in the number of electrons in (n-1)d-subshell while the number of electrons in ns-subshell remains the same. Some other general properties of d-block elements are discussed below:-

Table 2.01: Some Physical Constants of First Transition Series.

Elements:  Sc Ti V Cr Mn Fe Co Ni Cu Zn
1.Electronegativity 1.3 1.5 1.6 1.6 1.5 1.8 1.8 1.8 1.9 1.6
2. Covalent radii(A0) 1.44 1.32 1.22 1.17 1.16 1.16 1.16 1.15 1.17 1.25
3. Density(g/cm-3) 3.01 4.51 6.10 7.19 7.43 7.86 8.90 8.90 8.96 7.14
4. Ionic radii(A0):
(a) M2+ ion:
(b) M3+ ion:
 0.81
0.74		 0.91
0.76		 0.88
0.74		  0.84
0.69		 0.80
0.66		 0.76
0.64		 0.74
0.63		 0.72
0.62		 0.72  —– 0.74
—–
5. Melting point (oC) 1539 1668 1900 1875 1245 1536 1495 1453 1083 419.5
6. Boiling point(oC) 2730 3260 3450 2665 2150 3000 2900 2730 2595 906.0
7. Hydration energies (Kcal mol-1)
(a) For M2+ ions:
(b) For M2+ ions:		 —–
947		 446
1027		 453
1053		 460
1105		 445
1098		 468
1072		 497
1126		 509
—–		 507
—–		 491
—–
8. Ionization energies (KJmol-1)
(a) First (I1):
(b) Second (I2)
(c) Third (I3):		 632.6
12.45.1
2450.6		 659.0
1320.5
2721.3		 650.2
1376.1
2876.6		 652.3
1635.1
2994.9		 716.3
1513.3
3258.1		 762.3
1564.0
2963.9		 758.1
1647.0
3237.6		 736.0
1756.0
3400.7		 744.7
1961.0
3560.6		 906.7
1736.8
3838.8
Ionization potential (eV)
(a) First (I1):
(b) Second (I2)
(c) Third (I3)		 6.56
12.91
24.80		 6.83
13.69
27.50		 6.74
14.26
29.30		 6.76
16.95
31.00		 7.43
15.69
33.70		 7.90
16.21
30.60		 7.86
17.08
33.50		 7.63
18.21
35.20		 7.62
20.34
35.80		 9.39
18.00
39.70
9. Ea0M2+/M (Volts): —– -1.63 -1.13 -0.90 -1.18 -0.44 -0.27 -0.24 +0.34 -0.76
10. Ea0M3+/M2+ (Volts): —– +0.37 -0.255 -0.424 +1.54 +0.771 +1.92 +1.68 +2.00 —–

 

Table 2.02: Some Physical Constants of Second Transition Series.

Elements: Y Zr Nb Mo Tc Ru Rh Pd Ag Cd
1. Electronegativity: 1.2 1.4 1.6 1.8 1.9 2.2 2.2 2.2 1.9 1.7
2. Covalent radii(Ao): 1.80 1.58 1.46 1.39 1.36 1.34 1.34 1.37 1.44 1.54
3. Density (g/cm-3): 4.47 6.49 8.40 1021 11.50 12.20 12.40 12.0 10.51 8.65
4. Ionic radius(Ao) for stable oxidation state: 0.93 0.80 0.70 0.62 —– 0.69 0.86 0.50 1.26 0.97
5. Stable oxidation state: +3 +4 +5 +6 +4 +3 +3 +2 +1 +2
6. Melting point (oC): 1509 1852 2415 2610 2200 2500 1966 1552 960.8 321
7. Boiling point (oC): 2927 1500 3300 5560 —– 4900 4500 3980 2210 765
8. First ionization energy (kJ mol-1): 635.9 669.4 652.7 694.5 698.7 732.8 744.7 803.3 732.2 866.1
9. Heat of fusion
(kJ mol-1):		 11.3 16.7 26.7 27.6 23.0 25.5 21.7 16.7 11.3 6.1
10. Heat of Vaporisation (kJ mol-1): 389.1 502.0 —– 535.5 502.5 602.6 577.4 380.7 286.2 99.9

 

Table 2.03: Some Physical Constants of Third Transition Series.

Elements La Hf Ta W Re Os Ir Pt Au Hg
1. Electronegativity: 1.2 1.3 1.5 1.7 1.9 2.2 2.2 2.2 2.4 1.9
2. Atomic radiusAo): 1.69 1.58 1.46 1.39 1.37 1.26 1.26 1.29 1.44 1.57
3. Density (g/cm-3): 6.17 13.1 16.6 19.3 21.0 22.6 22.5 21.4 19.3 13.6
4. Stable oxidation state: +3 +4 +5 +6 +2 to+7 +4,+6 +3, +4 +2, +4 +1, +3 +2
5. Ionic radius(Ao) for stable oxidation state: 0.81 0.73 0.68 —– 0.67(+4) 0.60(+4) 0.52(+2) 1.37(+1) 1.10
6. Melting point (oC): 920 2222 2996 3410 3180 2700 2454 1769 1063 -38.4
7. Boiling point (oC): 3470 5400 5425 5930 5900 5500 5300 4530 2920 357
8. Ionisation energy (kJ mol-1):
(a) First (I1):		 —– 531.4 577.4 769.8 761.5 841.0 887.1 866.1 891.2 1008.3
9. Heat of fusion
(kJ mol-1):		 —– 21.7 28.4 33.7 33.0 26.28 27.6 21.7 12.7 2.3
10. Heat of Vaporisation (kJ mol-1): —– 6489.5 753.1 774.0 636.0 690.0 648.5 564.8 365.3 58.5

 

The above are the general properties of the transition elements. In the next chapter, we will study the general electronic configurations of these elements.

 

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