You are watching: All compounds have an electrical charge of
The substances defined in the preceding discussion are created of molecules that room electrically neutral; the is, the number of positively-charged protons in the cell core is equal to the number of negatively-charged electrons. In contrast, ions are atoms or assemblies of atom that have actually a net electrical charge. Ions that contain fewer electrons 보다 protons have a net optimistic charge and also are referred to as cations. Conversely, ion that contain more electrons 보다 protons have actually a net an unfavorable charge and are called anions. Ionic compounds save on computer both cations and also anions in a ratio that results in no net electrical charge.
In covalent compounds, electrons room shared in between bonded atoms and are simultaneously attracted to more than one nucleus. In contrast, ionic compounds save cations and anions quite than discrete neutral molecules. Ionic link are held together by the attractive electrostatic interactions between cations and anions. In an ionic compound, the cations and anions are arranged in an are to type an expanded three-dimensional range that maximizes the number of attractive electrostatic interactions and minimizes the number of repulsive electrostatic interactions (Figure \(\PageIndex1\)). As displayed in Equation \(\refEq1\), the electrostatic energy of the interaction in between two charged particles is proportional to the product that the dues on the particles and inversely proportional come the distance in between them:
\< \text electrostatic energy \propto Q_1Q_2 \over r \labelEq1\>
where \(Q_1\) and also \(Q_2\) are the electric charges on particles 1 and 2, and \(r\) is the distance in between them. Once \(Q_1\) and also \(Q_2\) are both positive, equivalent to the fees on cations, the cations repel every other and also the electrostatic power is positive. Once \(Q_1\) and \(Q_2\) room both negative, equivalent to the fees on anions, the anions repel every other and the electrostatic power is again positive. The electrostatic power is an unfavorable only when the charges have actually opposite signs; the is, positively charged varieties are attractive to negatively charged varieties and angry versa.
If the electrostatic energy is positive, the corpuscle repel each other; if the electrostatic energy is negative, the particles space attracted to each other.
One example of an ionic link is salt chloride (NaCl; figure \(\PageIndex3\)), developed from sodium and chlorine. In developing snucongo.orgical compounds, many facets have a propensity to get or lose sufficient electrons to obtain the same number of electrons as the noble gas closest to them in the regular table. As soon as sodium and also chlorine come into contact, each sodium atom gives up an electron to come to be a Na+ ion, through 11 protons in that nucleus yet only 10 electron (like neon), and each chlorine atom profit an electron to end up being a Cl− ion, v 17 proton in the nucleus and also 18 electron (like argon), as shown in part (b) in number \(\PageIndex1\). Solid salt chloride includes equal number of cations (Na+) and also anions (Cl−), thus maintaining electrical neutrality. Each Na+ ion is surrounded by 6 Cl− ions, and each Cl− ion is surrounded by 6 Na+ ions. Because of the big number the attractive Na+Cl− interactions, the full attractive electrostatic power in NaCl is great.
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Consistent with a propensity to have the same variety of electrons together the nearest noble gas, when developing ions, aspects in teams 1, 2, and also 3 tend to shed one, two, and three electrons, respectively, to kind cations, such as Na+ and Mg2+. They then have actually the same number of electrons together the nearest noble gas: neon. Similarly, K+, Ca2+, and also Sc3+ have 18 electrons each, favor the nearest noble gas: argon. In addition, the elements in group 13 lose three electron to kind cations, such together Al3+, again attaining the same number of electrons as the noble gas closest to them in the routine table. Because the lanthanides and also actinides formally belonging to team 3, the most common ion developed by these elements is M3+, whereby M represents the metal. Conversely, elements in teams 17, 16, and also 15 regularly react to obtain one, two, and also three electrons, respectively, to type ions such together Cl−, S2−, and P3−. Ions such as these, i beg your pardon contain only a solitary atom, are called monatomic ions. The fees of most monatomic ions acquired from the main group facets can be predicted by merely looking at the periodic table and also counting how numerous columns an aspect lies indigenous the too much left or right. For example, barium (in team 2) develops Ba2+ to have actually the same variety of electrons as its nearest noble gas, xenon; oxygen (in team 16) creates O2− to have the same number of electrons as neon; and cesium (in team 1) develops Cs+, which has the same variety of electrons as xenon. Note that this method is ineffective for most of the shift metals. Some common monatomic ions are detailed in Table \(\PageIndex1\).
|Li+ lithium||Be2+ beryllium||N3− nitride (azide)||O2− oxide||F− fluoride|
|Na+ sodium||Mg2+ magnesium||Al3+ aluminum||P3− phosphide||S2− sulfide||Cl− chloride|
|K+ potassium||Ca2+ calcium||Sc3+ scandium||Ga3+ gallium||As3− arsenide||Se2− selenide||Br− bromide|
|Rb+ rubidium||Sr2+ strontium||Y3+ yttrium||In3+ indium||Te2− telluride||I− iodide|
|Cs+ cesium||Ba2+ barium||La3+ lanthanum|