Ionic bonds in sodium chloride

Figure 3.12 Simplified diagram of ionic bonding in sodium chloride.

The strength of the ionic bond in sodium chloride arises from the electrostatic attraction between the sodium and chloride ions. These strong bonds explain why the properties of sodium chloride are so different from those of its constituent elements. For example,... 

The force of attraction between the l-i- charge on the sodium cation and the 1- charge on the chloride anion creates the ionic bond in sodium chloride. Recall that sodium chloride is the scientific name for table salt. Chemists call table salt by its scientific name because the word salt can actually be used to describe any one of thousands of different ionic compounds. Other salts that are commonly found in a laboratory include potassium chloride, magnesium oxide, and calcium iodide. 

Figure II.3 Donation and gain of an electron to form an ionic bond in sodium chloride. Reproduced from Tortora and Derrickson (2009) Principles of Anatomy and Physiology, 12th edn, Wiley International Student Version, New York. 2009 John Wiley Sons. Reprinted with permission of John Wiley Sons, Inc.

The ionic bonding in sodium chloride occurs when the valence electron from the third shell of the sodium atom is transferred to the chlorine atom. 

The ionic bonding in sodium chloride can also be described in terms of electron configurations. The sodium atom has the configuration Is 2s 2p 3s and the chlorine atom is Is 2s 2p 3s 3p. In the formation of sodium chloride, the electron in the 3s orbital of sodium is transferred to the half-filled 3p orbital of the chlorine atom. The sodium ion has the configuration Is 2s 2p and the chloride ion has the configuration Is 2s 2p 3s 3p. ... 

Ionic bonding in sodium chloride, NaCI showing a all electrons and b only the outer or valence electrons. The curved arrow indicates the transfer of an electron from the sodium atom to the chlorine atom... 

Fisure 2.11 Schematic representations of (a) the formation of Na and Cl ions and (b) ionic bonding in sodium chloride (NaCl). 

The bonds in sodium chloride are ionic Cl is present as chloride ion (Ch) Ch reacts ... 

In ionic bonding, atoms gain and lose electrons in order to achieve a noble gas electron configuration. Here s how Lewis symbols show this electron gain and loss in the ionic bonding of sodium chloride ... 

The bond in sodium chloride, for instance, is largely ionic. Sodium has transferred an electron to chlorine to give Na" and Cl" ions, which are held together in the solid by electrostatic attraction. The C-C bond in ethane, however, is fully covalent. The two bonding electrons are shared equally by the two equivalent carbon atoms, resulting in a symmetrical electron distribution in the bond. Between these two extremes lie the great majority of chemical bonds, in which the electrons are attracted somewhat more strongly by one atom than by the other. We call such bonds, in which the electron distribution is unsymmetrical, polar covalent bonds. 

A pure covalent bond (an H-H bond for example) exhibits 0 % ionic character while a polar covalent bond like hydrogen fluoride (H-F) exhibits 42 % ionic character. Bonds in sodium chloride (NaCl) are normally considered as ionic. These sodium chloride bonds exhibit 72 % ionic character. This emphasizes that the transition between covalent bonds over polar covalent bonds to ionic bonds is very fluent. No bonds actually exhibit 100 % ionic character since the bond electrons always will be located around the less electronegative atom at least for just a very little percentage of the time. 

Year 12 Australian students asked about sodium chloride were found to often volunteer a description of how ions might be formed through an electron transfer event (i.e. from sodium atom to chlorine atom). It was also common for these students to refer to molecules of NaCl, and some believed that there were two types of bond in sodium chloride either that the NaCl molecules had internal covalent bonds, but were ionically bonded to other molecules, or vice versa (Butts Smith, 1987). Some of the students thought that this assumed molecular nature of sodium chloride explained why the solid did not conduct electricity, believing that ions were only formed from the molecules on dissolving. One student thought that each ion would have one ionic bond, and five physical bonds (p. 196). 

The ionic bond is the most obvious sort of electrostatic attraction between positive and negative charges. It is typified by cohesion in sodium chloride. Other alkali halides (such as lithium fluoride), oxides (magnesia, alumina) and components of cement (hydrated carbonates and oxides) are wholly or partly held together by ionic bonds. 

Fig. 4.3. The formation of an ionic bond - in this case between a sodium atom and a chlorine atom, making sodium chloride.

The ionic model, the description of bonding in terms of ions, is particularly appropriate for describing binary compounds formed from a metallic element, especially an s-block metal, and a nonmetallic element. An ionic solid is an assembly of cations and anions stacked together in a regular array. In sodium chloride, sodium ions alternate with chloride ions, and large numbers of oppositely charged ions are lined up in all three dimensions (Fig. 2.1). Ionic solids are examples of crystalline... 

In the classroom, ionic bonding is mostly introduced by the example of simple ionic substances like sodium chloride. Starting from the electronic configuration of... 

Formation of the ionic bond between sodium and chloride ions in the NaCl crystal. 

When two or more ions bond together chemically, it is called an ionic bond. In an ionic bond, the ions are attracted to one another because they have opposite charges. In general, ionic bonds form between a metal and a nonmetal. Since sodium is a metal and chlorine is a nonmetal, when they bond, an ionic bond is formed and sodium chloride is produced. 

A is correct. Sodium chloride is a protolypic example of an ionic bond. In a coordinate covalent bond, both shared electrons come from the same atom for instance, a Lewis base (i.e., ammonia) or oxygen-containing compound (i.e., water). Although both shared electrons come from the same atom, a coordinate covalent bond is a single bond similar in chemical properties to a covalent bond. 

Films of the complexes are stable in water at a pH of 7 while they dissolve at pH 5. This can be explained by the pKa value of retinoic acid, which is, for example, 6.05 in 150 mM NaCl and 6.49 in 5 mM NaCl [163]. Therefore, the anionic retinoic moieties within the complexes will be protonated at pH values lower than the pKa which lead to the cleavage of the ionic bonds in the complexes. The first experiments to evaluate the release properties of retinoic acid from thin films of the complexes were performed by using FTIR and surface tension measurements. Films were immersed in solutions of 0.15 m sodium chloride at pH 5 for both methods. The increase of the absorbance at 1255 cm-1 (C-0 stretch vibration) [186] in the FTIR spectra was used as a qualitative measure for the release of retinoic acid from the PEI-retinoate complexes. For comparison, the spectra of the complex and of the non-com-plexed retinoic acid are shown at wave numbers around 1255 cm 1 (Fig. 26, insert curves a and b). The time-dependency of the absorbance, which is a relative measure of the amount of released retinoic acid, is shown in Fig. 26. It can be seen that the increase of the absorbance, and therefore the release... 

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