Iodine Ionic bonding

F or a completely ionic bond the ionicity, I, must be 1 for a completely covalent bond, 1 = 0. For the alkali iodides the ionicity and hence the number of iodine 5p electrons (y = 5 + 1) should increase from Lil to Csl since the electronegativity difference between iodine and the alkali increases. This implies that the iodine ion configuration, 5 5p, should most closely approach the 5s 5p xenon configuration for Csl. Since is decreased by increases in the 5p population, we would... 

Organic substances such as methane, naphthalene, and sucrose, and inorganic substances such as iodine, sulfur trioxide, carbon dioxide, and ice are molecular solids. Salts such as sodium chloride, potassium nitrate, and magnesium sulfate have ionic bonding structures. All metal elements, such as copper, silver, and iron, have metallic bonds. Examples of covalent network solids are diamond, graphite, and silicon dioxide. 

The correct answer is choice B. Potassium iodide is formed from a metal, potassium, and a nonmetal, iodine. The type of bonding that forms between metals and nonmetals is ionic bonding. 

Using electron-dot structure, diagram the formation of an ionic bond between potassium and iodine. 

According to the NMR chemical shifts ofthe a-CF2 group, the ionic character of the iodine-X bond increases for substituents X in the order Cl < OSO2CH3 < OSO3H < OTf. Even for the most electronegative triflate group the I-OTf bond is strongly polarized but not really ionic in nature [13c] (Scheme 2.145). 

Scheme 2.145 For aryl perfluoroalkyliodonium reagents — even for the triflates - the iodine—counterion bond is strongly polarized but not completely ionic [13c].

Figure 2. The tetrahedron of bonding types. Typical examples are metallic-copper ionic-NaCL covalent network-diamond van der Waals, molecular-iodine. Hydrogen bonding would be represented by the cross-hatched area near to van der Waals types of bonding.

Just as the atom takes on a significance in learning about chemistry which is not justified in terms of the (lack of) role that discrete atoms play in chemical processes, once learners have been taught about molecules there is a tendency to apply the molecule schema to all structures. The role of valency in limiting, if not exactly determining, molecular formulae, may be extended to metals and to ionic materials. Metals may be seen by students to consist of discrete molecules of similar atoms, in a similar way to iodine or phosphoms. In the ionic case, valency is seen by many students to indicate the number of ionic bonds that can be formed, and not just the charge on the ions. 

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