Transition metals atomic radii

Symbol Fe atomic number 26 atomic weight 55.847 a Group VIII (Group 8) metallic element transition metal atomic radius 1.24A electron configuration [Ar]3d 4s2 most common valence states +2 and -i-3 other oxidization states -1, 0, -1-1, +4 and -i-6 are known but rare most abundant isotope Fe-56 natural isotopes and their abundances Fe-54 (5.90%), Fe-56 (91.52%), Fe-57 (2.245%), Fe-58 (0.33%). 

Fig. 1. Space filling representation of Qq and the hollow cavity within it, shown next to a transition metal atom (radius = 2.0 A) for size comparison. The structures were ray-traced with POV-Ray Tracer 3 downloadable at http //www.povray.org. Note that the atoms are not hard as perhaps suggested here by the metallic surfaces metal atoms can bury themselves significantly within the 71-cloud of the carbon shell through metal-to-carbon bonding...

The above results for ZnS, CdS, and HgS indicate that an additional electron in a transition-metal atom increases its radius by 0.03 A. 

Many main-group atoms have been found to occupy interstitial positions in transition metal carbonyl clusters and there are now examples of H, B, C, N, O, Si, P, S, Ge, As, Sn, and Sb atoms being encapsulated, either fully or partially, within a metal skeleton. In general, the size limitations associated with the internal cavity of the cluster determine the type of atom which can occupy the interstitial site. Although the radius of the cavity is determined primarily by the nuclearity and geometry of the cluster, the size of the metal atoms relative to that of the interstitial atom is a critical factor, and clusters with larger cavities are observed as the ratio of the covalent radius of the main-group atom to that of the transition metal atoms increases. 

The size of the transition-metal atoms decreases shghtly from left to right in the periodic table. What factors must be considered in explaining this decrease In particular, why does the size decrease at aU, and why is the decrease so gradual Predict the largest and smallest radius in each series, and account for your choices ... 

TABLE 4.18 Synopsis for the Structural Parameters Employed in this Work for the Second, Third and Fourth Period Transitional Metals Atomic Number (Z), Atomic Mass (A), Atomic Radius (R), Melting Point (MP), Boiling Point (BP), Density (p) (Horovitz et al., 2000), Finite Difference Electronegativity (x-FD) and Chemical Hardness (rj-FD), Experimental Ionization Potential (EXP-IP) and Electronic Affinity (EXP-EA) (Putz, 2008a), and Their Density Functional Theory Third Order (DFT[3]) Counterpart (Putz, 2006)... 

Binary and ternary structure types with isolated B atoms are listed in Table 1. In the metal borides of the formula (My, Mi ),B or T,(B, E) (M-p, M - = transition metals, E = nonmetal), the influence of the radius ratio as well as the... 

Symbol Dy atomic number 66 atomic weight 162.50 a lanthanide series, inner transition, rare earth metal electron configuration [Xe]4 5di6s2 atomic volume 19.032 cm /g. atom atomic radius 1.773A ionic radius 0.908A most common valence state +3. 

Symbol Hf atomic number 72 atomic weight 178.49 a Group IV B (Group 4) transition metal element atomic radius 1.442A electron configuration [Xe]4/i45d26s2 common valence +4, also exhibits oxidation states +2 and -i-3 most abundant natural isotope Hf-180 isotopes and their natural abundances Hf-176 (5.21%), Hf-177 (18.56%), Hf-178 (27.10%), Hf-179 (13.75%), Hf-180 (35.22%), artificial isotopes 157, 158, 168, 173, 175, 181-183. 

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