Ions Electron Configurations and Sizes

This case is similar to the third type in Table 8.2, and the bond polarities cancel. The molecule has no dipole moment. 

This case is analogous to the water molecule, and the polar bonds result in a dipole moment oriented as shown  

IBLG See questions from Ions, Ionic Compounds, and Bond Energies  

Atoms in stable compounds usually have a noble gas electron configuration. 

Unless otherwise noted, all art on this page is Cengage Learning 2014. 

When two nonmetals react to form a covalent bond, they share electrons in a way that completes the valence electron configurations of both atoms. That is, both nonmetais attain nobie gas eiectron configurations. 

When a nonmetal and a representative-group metal react to form a binary ionic compound, the ions form so that the vaience eiectron configuration of the nonmetal achieves the eiectron configuration of the next nobie gas atom and the valence orbitals of the metal are emptied. In this way both ions achieve noble gas electron configurations. 

These generalizations apply to the vast majority of compounds and are important to remember. We will deal with covalent bonds more thoroughly later, but now we will consider what implications these rules hold for ionic compounds. 

In the solid state of an ionic compound the ions are relatively close together, and many ions are simultaneously interacting  

In the gas phase of an ionic substance the ions would be relatively far apart and would not contain large groups of ions  

The presence of polar bonds does not always yield a polar molecule. 

The SO3 molecule Because the electronegativity of oxygen (3.4) is greater than that of sulfur (2.6), each oxygen has a partial negative charge, and the sulfur has a partial positive charge  

As we will see later, there are exceptions to these rules, but they remain a useful place to start. 

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Types of Chemical Bonds electronegativity Bond Polarity and Dipole Moments Ions Electron Configurations and Sizes Predicting Formulas of Ionic Compounds Sizes of Ions... 

The simplest reactions to study, those of coordination complexes with solvent, are used to classify metal ions as labile or inert. Factors affecting metal ion lability include size, charge, electron configuration, and coordination number. Solvents can by classified as to their size, polarity, and the nature of the donor atom. Using the water exchange reaction for the aqua ion [M(H20) ]m+, metal ions are divided by Cotton, Wilkinson, and Gaus7 into four classes ... 

The following discussion is restricted to such structural elements already observed in transition metal fluorides, whereas others, examples of which are not known yet, were omitted. Later on influences will be described that may affect crystal structures by means of size, charge, electronic configuration and bonding of the constituent ions of a compound. 

The number of ligand donor atoms that surround a central metal ion in a complex is called the coordination number of the metal. Thus, platinum(II) has a coordination number of 4 in Pt(NH3)2Cl2, and iron(III) has a coordination number of 6 in [Fe(CN)6]3-. The most common coordination numbers are 4 and 6, but others are well known (Table 20.4). The coordination number of a metal ion in a particular complex depends on the metal ion s size, charge, and electron configuration, and on the size and shape of the ligands. 

All the lanthanides have similar outer electronic configuration and display mainly + 3 oxidation state in their compounds, therefore, lanthanides have exceedingly similar chemical properties. Their similarity is much closer than that of ordinary transition elements because lanthanides differ mainly in the number of 4/electrons which are buried deep in the atoms of lanthanides and thus don t influence their properties. Moreover, due to lanthanide contraction there is a very small difference in the size of all the fifteen tri valent lanthanide ions. Thus, for all practical purposes, the size of these ions is almost identical which results in similar chemical properties of these elements. 

Describe the general properties of metals and nonmetals and understand how trends in metallic behavior relate to ion formation, oxide acidity, and magnetic behavior understand the relation between atomic and ionic size and write ion electron configurations ( 8.5) (SPs 8.6-8.8) (EPs 8.47-8.65)... 

For these three materials, all have nearly equal anion and cation masses, similar closed shell electronic configurations, and nearly the same ratios of anion to cation ionic radii, —1.35 [64]. Yet aside from the RW vibrational modes, the characteristic vibrational patterns differ significantly. This is especially true for the crossing modes which appear to exist across the Brillouin zone only for RbBr and for the optical modes which are seen in NaF but not in KCl and RbBr. The differences certainly lie with the quite different balance of forces, Coulombic versus short-range repulsions, attributable to the range of sizes and polarizabilities of the ions, particularly of the anions. This absence of similarity also illustrates the importance of close collaborations between theoretical and experimental groups in the analysis and interpretation of HAS data. 

The coordination number of the metal center depends on the size of the metal ion, the charge of the ion, the electronic configuration, and on the size and shape of the ligands. Coordination numbers of 4 and 6 are most common, but they can range from anywhere between 2 to 9. 

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