The substances defined in the preceding discussion are written of molecules that are electrically neutral; the is, the variety of positively-charged protons in the cell nucleus is same to the variety of negatively-charged electrons. In contrast, ions room atoms or assemblies of atom that have a net electric charge. Ion that contain under electrons than protons have actually a net positive charge and are referred to as cations. Conversely, ion that contain an ext electrons 보다 protons have a net negative charge and also are referred to as anions. Ionic compounds contain both cations and also anions in a proportion that results in no net electric charge.

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Note

Ionic compounds save both cations and also anions in a ratio that outcomes in zero electric charge.

In covalent compounds, electrons room shared between bonded atoms and also are concurrently attracted to an ext than one nucleus. In contrast, ionic compounds save cations and anions rather than discrete neutral molecules. Ionic link are hosted together by the attractive electrostatic interactions in between cations and anions. In one ionic compound, the cations and also anions are arranged in an are to type an prolonged three-dimensional range that maximizes the number of attractive electrostatic interactions and also minimizes the number of repulsive electrostatic interaction (Figure 2.7.1). As displayed in Equation 2.7.1, the electrostatic energy of the interaction in between two fee particles is proportional to the product that the fees on the particles and also inversely proportional come the distance in between them:

\< \text electrostatic energy \propto Q_1Q_2 \over r \tag2.7.1\>

where $$Q_1$$ and also $$Q_2$$ are the electric charges on particles 1 and also 2, and $$r$$ is the distance in between them. Once $$Q_1$$ and also $$Q_2$$ are both positive, corresponding to the dues on cations, the cations repel every other and the electrostatic power is positive. As soon as $$Q_1$$ and also $$Q_2$$ space both negative, equivalent to the fees on anions, the anions repel every other and the electrostatic power is again positive. The electrostatic power is negative only as soon as the charges have actually opposite signs; that is, positive charged types are attractive to negative charged species and evil versa.

Note

If the electrostatic power is positive, the particles repel each other; if the electrostatic energy is negative, the particles room attracted to each other.

One example of an ionic link is sodium chloride (NaCl; figure 2.7.3), formed from sodium and chlorine. In creating gaianation.netical compounds, many elements have a propensity to acquire or lose sufficient electrons to achieve the same number of electrons together the noble gas closest to them in the periodic table. When sodium and chlorine come right into contact, each salt atom provides up one electron to become a Na+ ion, through 11 proton in its nucleus but only 10 electrons (like neon), and also each chlorine atom profit an electron to end up being a Cl− ion, v 17 proton in that nucleus and 18 electron (like argon), as shown in component (b) in figure 2.7.1. Solid sodium chloride contains equal number of cations (Na+) and anions (Cl−), thus maintaining electrical neutrality. Every Na+ ion is surrounded by 6 Cl− ions, and each Cl− ion is surrounded by 6 Na+ ions. Due to the fact that of the huge number the attractive Na+Cl− interactions, the full attractive electrostatic power in NaCl is great.

Figure 2.7.3 salt Chloride: an Ionic Solid. The plane of an NaCl decision reflect the regular three-dimensional setup of the Na+ (purple) and also Cl− (green) ions.

Note

Elements in teams 1, 2, and 3 often tend to kind 1+, 2+, and 3+ ions, respectively; elements in teams 15, 16, and 17 tend to form 3−, 2−, and 1− ions, respectively.

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Exercise 2.7.1

Predict the fee on the most typical monatomic ion developed by every element.

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