Barium atom

For arrangements (a) and (b) the structure factor in the first order is 4Ba for planes with hSG even and kSG + lSG even, and 0 for all other planes. These arrangements are definitely eliminated by the experimental data for example, (411)SG is absent, and (521)sg> with smaller interplanar distance, reflects very strongly at the same wave length. Such wide discrepancies cannot be explained as due to the effect of sulfur and oxygen atoms. The barium atoms are, therefore, located as in (c). Because of the presence of other atoms no attempt was made to determine the two parameters involved. 

Example Determination of Barium in alkaline-earth mixtures affords a potential matrix interference due to absorption. It has been observed that an intense and useful absorption line for barium atoms, occurring at 553.6 nm, lies in the centre of a broad absorption band for Ca (OH)2, that extends from 540 to 560 nm. 

Although the structural features of the anionic part of all compounds 12-16 are comparable, these structures are entirely different with respect to the cationic parts and relative positions of cations and anions within the unit cell. In the crystal lattice of 12 each potassium atom has long-range interactions with seven carbon atoms. In 13 and 14 each barium atom has an interaction with two carbon atoms [C(l) and C(3)] of two adjacent... 

Barium hydroxide octahydrate, Ba(OH)2 8 H20, is a crystalline compound that contains eight water molecules clustered around the barium atom. We ll learn more about hydrates in Section 14.15. 

Figure 24 The same as in Figures 22 and 23, but for the free (Ba) and encaged ( Ba) barium atom [29].

Neutron activation analysis (NAA) technique has also been used for determining low levels of barium in human blood (Olehy et al. 1966). This technique is based on the interaction of the nuclei of individual barium atoms with neutron irradiation, resulting in the emission of x-rays (photons). Detection limits of 7 pg barium/L of erythrocyte and 66 pg barium/L of plasma were obtained (Olehy et al. 1966). The advantages of the NAA technique are its nondestructive nature of sample and minimum sample manipulation. Disadvantages of this technique include its high costs and a nuclear reactor may not be readily available to many laboratories. 

Similar insertions of strontium or barium atoms into M14— M14 bonds also afforded Mi4-group (II) compounds (equation 71)3a. 

The barium in barium sulfate (BaS04) is the Ba2+ ion. Does this ion have a different number of neutrons than the neutral barium atom ... 

The barium ion and the barium atom have the same number of neutrons. 

Definite layers, more than one molecule thick, can however be obtained on metals under certain special conditions. Instances of these are the monatomic layer of caesium on top of a monatomic layer of oxygen, and the similar layers of alternate oxygen and barium atoms, which are of such importance for thermionic emission (Chap. VIII, 4). 

Fig. 4. ORTEP drawing (50% probability level) of Ba(N(SiMe3)2 )2(THF)2 showing the distorted tetrahedral ligand geometry around the barium atom. The Ba—N and Ba—O bond distances have average values of 2.592(6) and 2.731(20) A, respectively, and the O-Ba-O, O-Ba-N, and N-Ba-N bond angles have a range of 91.44(2)—128.54(21)°, respectively. (Redrawn from Ref. 28.)...

Fig. 6. ORTEP drawing of Ba[N(SiMe3)2]2(THF) 2. The molecule resides on a crystallographic two-fold axis that intersects the bridging nitrogen atoms. The geometry around each barium atom is crudely tetrahedral with internal angles in the range of 83.3(3)-136.1(3)°. (Redrawn from Ref. 28.)...

Fig. 20. ORTEP drawing of [BaCpj fjU-l,4-pyrazine) showing the pyramidal geometry around each barium atom. Each barium atom lies 0.65 A out of the plane defined by the two ring centroids and the nitrogen atom of the pyrazine ligand. (Redrawn from Ref. 103.)...

Fig. 26. ORTEP drawing of Ba2(OCPh3 )4 (THF)3 showing the square pyramidal coordination geometry around each barium atom. The two square pyramids share a common triangular face comprising the three -oxygen atoms of the alkoxide ligands. (Redrawn from Ref. 49.)...

Fig. 32. The structure of Ba4(tmhd)8 (r-Bu groups omitted for clarity). The barium atoms occupy the vertices of a fairly regular rhombohedron with an average Ba---Ba distance of 4.152(5) A. The /3-diketonate ligands bridge and chelate the metal centers in four distinct bonding modes. (Redrawn from Ref. 177.)...

---