Oxygen atomic radius

Note that the N3- ion (radius 171 pm) is much larger than the nitrogen atom, for which the covalent radius is only 71 pm. The oxygen atom (radius 72 pm) is approximately half the size of the oxide ion... 

The radii av a2 and coordination numbers zv z2 follow from x-ray analysis (cf. Section I.B), and aQ/2 — 1.25 A corresponds to Pauling s van der Waals radius of 1.40 A for a covalently bound oxygen atom.25 The value of eQlk — 166.9°K was chosen to obtain agreement between calculated and experimental values of the equilibrium vapor pressure of argon hydrate at 0°C. 

Iron corrodes in the presence of oxygen to form rust, which for simplicity can be taken to be iron(lll) oxide. If a cubic block of iron of side 1.5 cm reacts with 15.5 L of oxygen at 1.00 atm and 25°C, what is the maximum mass of iron(III) oxide that can be produced Iron metal has a bcc structure, and the atomic radius of iron is 124 pm. The reaction takes place at 298 K and 1.00 atm. 

Other Covalent Radii. In Cu20 and Ag20 each metal atom is equidistant from two nearest oxygen atoms, the interatomic distances corresponding to the radius values 1.18 and 1.39 A for Cu1 and Agl with coordination number two. In KAg(GN)2, in which each silver atom is similarly attached to two cyanide groups1), the effective radius of Agl is 1.36 A. It has been pointed out to us by Dr. Hoard that the work of Braekken2) indicates the presence of strings —Ag—G=N—Ag—G... 

Figure 2.8 Average radius Rav and effective or trispyrazole [22], oxygen atoms of the charge Zf resulting from the REC correction POM series LnW10 and LnW22, [23] and halo-of different homoleptic compounds nitro- genides F , Cl-, Br" anions [21]. genated ligands of the type bis-pyrazole...

The remaining compounds listed in Table II all adopt structures with infinite metal-metal bonded chains consisting of octahedral cluster units fused on opposite edges. However, because of the large difference in effective ionic radius of the cations concerned, very different lattice types are dictated. The compounds NaMoi 06 (19,22) and Bas(Moit06)8 (17) adopt tunnel structures with the Na+ or Ba2+ ions located in sites along the tunnels with 8-fold coordination by oxygen atoms. 

In the C60 fragment all the carbon atoms are tricoordinated, except Cl and C2, which, being coordinated to an oxygen atom of the metal fragment, are tetracoordinated. As shown in Scheme 1, the sphere of carbon atoms, which has an approximate radius of 3.51 A, is composed of 20 six-membered rings fused with 12 five-membered rings with a repetition of the pyracylene building unit. 

Figure 3. The conformational sphere for pyranoid rings. The perfect chairs are at the north and south poles (0=0 and 180 , respectively). The boat and skew (B and S designations) at the equator permit pseudorotation that is slightly hindered, at least for cyclohexane. The envelopes, E (also called sofas and half-boats), and half-chairs, H, are not observed for rings coiqposed of saturated carbon and oxygen atoms, but are iiqportant forms for rings with unsaturated carbon atoms. The aiqplitude of puckering corresponds to the radius of the sphere.

Table 8. Radius of the minimal cavity enclosed by n oxygen atoms (97)...

Obviously, the minimal radius of the enclosed cavity increases gradually with the number of the coordination sites available (Table 8). Thus, for alkali and alkaline earth cations an upper limit is set at 12 coordinating atoms beyond that, the radius of the minimal cavity, and more impressively that of the equilibrium cavity, would exceed the radius of the cations. Accordingly, all of the known carrier antibiotics specific for alkali ions display 5—8 coordinating oxygen atoms (Table 1), thereby providing an adequate cavity. 

---