Electrostatic force of attraction

The Electrostatic Energy. In Chapter 2 we drew attention to the fact that, when a proton transfer (117) has been carried out in a solvent, the electrostatic fields of two ions have been created and work must have been done to supply the amount of energy associated with these ionic fields. Let us now compare (117) with the process (123), both in aqueous solution at the same temperature. In both cases an (HaO)+ ion will be formed but in (123), when the proton is removed from the (IIS04)-ion, we have to separate the particles against the mutual attraction of the proton and the doubly charged ion (S04)". Consequently, more work must be done against the electrostatic forces of attraction than in the removal of a proton from a neutral particle. 

The crystallographic radius assigned to the ion Fc+++ is comparable with that assigned to the scandium ion Sc+++. The ions K, Ca+t, and Sc+++ have the same number of electrons, and the same closed electronic shells as the argon atom. In aqueous solution there will be electrostatic forces of attraction between Ca++ and Cl, and between 8c+ t+ and Cl- but the quantum-mechanical forces between these ions will be forces of repulsion only. Between Fe+++ and Cl-, on the other hand, there may be quantum-mechanical forces of attraction. In view of the rather intense electrostatic attraction between Fe+++ and a negative ion, a 1 E. Rabinowitch and W. H. Stockmayer, J. Am. Chern. Soc., 64, 341 (1942). 

Water is the most common solvent used to dissolve ionic compounds. Principally, the reasons for dissolution of ionic crystals in water are two. Not stated in any order of sequence of importance, the first one maybe mentioned as the weakening of the electrostatic forces of attraction in an ionic crystal known, and the effect may be alternatively be expressed as the consequence of the presence of highly polar water molecules. The high dielectric constant of water implies that the attractive forces between the cations and anions in an ionic salt come down by a factor of 80 when water happens to be the leaching medium. The second responsible factor is the tendency of the ionic crystals to hydrate. 

Ionic bonding is the electrostatic force of attraction between oppositely charged ions (+ and -), which are formed as a result of electron transfer between atoms. 

Much more heat energy is released (1) when electrostatic forces of attraction between oppositely charged ions (Mg2+ and O2-) are made (1). Suggest questions require lateral thinking rather than recall . 

To melt sodium chloride, very strong (1) electrostatic forces of attraction between positive and negative ions (1) must be overcome. Do not just write strong bonds . 

Ionic compounds are made up of positively charged ions (usually metal ions) and negatively charged ions (usually non-metal ions or polyatomic anions) held together by electrostatic forces of attraction. Molecular compounds are made up of discrete units called molecules. Generally they consist of a small number of nonmetal atoms held together by covalent bonds (sharing of electrons). 

The Na+ and Cl- ions can be considered as negatively and positively charged spheres that attract each other. Since positive (+) and negative (-) charges form an electric field in all directions, the electrostatic force of attraction (ionic bond) is not just in one direction. In the NaCl crystal, each Na+ ion is surrounded by six Cl- ions and each Cl- ion is surrounded by six Na+ ions (Figure 2). Because of this, the structure of NaCl is not a molecule but it is in the form of an ionic crystal in which many ions are found together. 

The electrostatic force of attraction, F, between two charges, qy and q2, separated by a distance, d, is given by... 

The melting point of NaCl is 801°C, of CaCl2 is 782°C, and of AICI3 is 190°C. The electrostatic forces of attraction between ions increase with an increase in the charge. In these ionic solids, the charge on the cations Na", Ca ", and Al ... 

The rest of the atom surrounding the nucleus is where electrons are most likely to be found. The electrons are negatively charged and move around very quickly in electron shells or energy levels. The electrons are held within the atom by an electrostatic force of attraction between themselves and the positive charge of protons in the nucleus (Figure 3.2). 

Electrostatic force of attraction A strong force of attraction between opposite charges. 

Giant ionic structure A lattice held together by the electrostatic forces of attraction between ions. 

Ionic (electrovalent) bond A strong electrostatic force of attraction between oppositely charged ions. 

Metallic bond An electrostatic force of attraction between the mobile sea of electrons and the regular array of positive metal ions within the solid metal. 

Aluminium oxide is an ionic compound. When it is melted the ions become mobile, as the strong electrostatic forces of attraction between them are broken by the input of heat energy. During electrolysis the negatively charged oxide ions are attracted to the anode (the positive electrode), where they lose electrons (oxidation). 

Nucleus It is that portion of the atom which contains protons and neutrons. It is positively charged and the negatively charged electrons are attracted to the nucleus by the electrostatic forces of attraction. 

The value of the fraction representing the ratio of the conductances of two differently concentrated but fully dissociated solutions can be calculated from Onsager s equation (see III-14) which enables us to determine the effect of electrostatic forces of attraction in strong, i. e. fully dissociated electrolytes. In the case of weak electrolytes, however, it is necessary to substitute ct in Onsager s equation by the real concentration of ions, i. e. by equivalent conductance of a hypothetical, fully dissociated solution is considered. In this way we obtain the following equation ... 

If the viscosity curve is convex, the molecules of both components are polar. This increase in viscosity may also be explained by the electrostatic forces of attraction of the dipoles, which result in an increase of the viscosity. The occurrence of a maximum in the convex curve often corresponds to the presence of a definite additive compound of the components, the existence of which may be verified by other physico-chemical methods. 

Evans and Spurlin have studied the effect of carboxyl groups present in 0-ethylcellulose on its viscosity in dilute solution. Although free carboxyl groups do not affect viscosity, neutralization with metal ions increases the viscosity, especially in non-polar solvents. According to these workers, the effect of bound, metal ions is to produce large electrostatic forces of attraction between the chains to which they are attached. 

In Unit 2.3 we learned about hydrogen bonds. These are inter-molecular electrostatic forces of attraction between certain polar molecules (often water). When an ionic solid is stirred into water, the polar water molecules surround the particles and electrostatic bonds are formed between the oxygen and the metal ion and also between the hydrogen and the anion. These bonds help the solid to dissolve and break into individual ions (Figure 4.6.3). This process is called hydration. 

Generally speaking, chemical forces extend over very short distances a covalent bond can be formed only by a merging of electron clouds. Electric forces extend over longer distances. The electrostatic force of attraction or repulsion between two point charges, q and q2, separated by distance x is given by Coulomb s law ... 

Ionic. Ionic materials are those that are brittle and that conduct electricity when molten but not as solids. Melting points range upwards from about 500°C. Examples are CaO (quicklime), Mgp2, and NaCl (common table salt). The electrons are constrained about each atom, some atoms with excess positive charge (cations) and some with excess negative charge (anions). The ions are packed closely together, held by coulomb (electrostatic) forces of attraction. 

When two solid surfaces come in contact with each other, electrostatic forces of attraction arise as a result of the contact potential, forming electrical double layers. 

Large polyelectrolytes, such as nucleic acids, and polyampholytes, such as proteins, are classified together as macroions. The electrostatic forces of attraction or repulsion between such charged particles play a major role in determining their behavior in solution. 

Lattice energy is directly related to the size of the ions bonded. Smaller ions form compounds with more closely spaced ionic charges. Because the electrostatic force of attraction between opposite charges increases as the distance between the charges decreases, smaller ions produce stronger interionic attractions and greater lattice energies. 

In the cyclopentyl series, 5y/i-elimination occurs from a planar transition state, but a/in -elimination is slightly distorted from a dihedral angle of 180°. Consequently, the preference for n/m -elimination is less marked in the five-than in the six-membered ring systems (Table 12). With the small neutral base trimethylamine, electrostatic forces of attraction between the sulphonate ester and the partially neutralised base balance the normal preference for n/iti-elimination and the reaction is almost non-stereospecific. None of the reactions follows the carbanion mechanism, as general base catalysis is observed for the 2-p-tolylsulphonylcyclopentyl tosylate elimination and the studies on 2-phenylcyclopentyl tosylates revealed large isotope effects (A h/A d) and p values smaller than in the 2-phenylethyl series (see Table 9, p. 209) " . 

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