Opposite charges attract

All of the material in this text and most of chemistry generally can be understood on the basis of what physicists call the electromagnetic force Its major principle is that opposite charges attract and like charges repel As you learn organic chemistry a good way to start to connect structure to properties such as chemical reactivity is to find the positive part of one molecule and the neg ative part of another Most of the time these will be the reactive sites... 

All of the forces in chemistry except for nuclear chemistry are electrical Opposite charges attract like charges repel This simple fact can take you a long way... 

The world of science is a deliciously excruciating blend of the general and the specific. There are general laws and rules of broad application (E=mc, opposite charges attract), but the precise way in which these laws combine in any particular instance always depends on the specifics of the situation. 

Since opposite charges attract each other, the cations attract the anions, forming an ionic compound. Ionic compounds are neutral so that the number of positive charges would equal the number of negative charges. The potassium cation would attract the chloride anion to form the ionic compound potassium chloride, KC1. We call ionic compounds such as this salts. 

In the mucosal environment, effects of salt, pH, temperature, and lipids need to be taken into consideration for possible effects on viscosity and solubility. A pH range of 4-7 and a relatively constant temperature of 37°C can generally be expected. Observed solution properties as a function of salt and polymer concentration can be referred to as saline compatibility. Polyelectrolyte solution behavior [27] is generally dominated by ionic interactions, such as with other materials of like charge (repulsive), opposite charge (attractive), solvent ionic character (dielectric), and dissolved ions (i.e., salt). In general, at a constant polymer concentration, an increase in the salt concentration decreases the viscosity, due to decreasing the hydrodynamic volume of the polymer at a critical salt concentration precipitation may occur. 

It is a remarkable thing for an ionic compound to dissolve in water. You probably learned at some point that opposite charges attract each other. The energy cost of separating positively charged cations from negatively charged anions is immense. Dissolution occurs only because water interacts very effectively with ions. We will explore this phenomenon more fully in chapter 8. For now, however, you just need to accept that when ionic compounds dissolve in water, they (mostly) separate into ions that freely and independently move around in the solution. Since these ions are free to move around in the solution, the solution conducts electricity. 

The forces holding ions together in ionic solids are electrostatic forces. Opposite charges attract each other. These are the strongest intermolecular forces. Ionic forces hold many ions in a crystal lattice structure... 

Because ions with opposite charges attract each other, an ionic bond results from the attractive force between the positively charged cation and the negatively charged anion. A typical ionic compound is a high-melting solid. In the solid crystal, several anions surround each cation. Each of these anions is attracted equally to the cation. Likewise, each anion is surrounded by several identical cations that are equally attracted to the anion. Because of these multiple interactions, we cannot say that a particular cation is bonded to a particular anion. Therefore, we do not speak of a molecule of an ionic compound, because this would imply one cation associated with one anion. 

A. Opposite charges attract, and the more protons there... 

One could use the Debye-Hiickel ionic-atmosphere model to study how ions of opposite charges attract each other, (a) Derive the radial distribution of cation ( +) and anion (nj concentration, respectively, around a central positive ion in a dilute aqueous solution of 1 1 electrolyte, (b) Plot these distributions and compare this model with Bjerrum s model ofion association. Comment on the applicability of this model in the study of ion association behavior, (c) Using the data in Table 3.2, compute the cation/anion concentrations at Debye-HUckel reciprocal lengths for NaCl concentrations of lO and 10 mol dm", respectively. Explain the applicability of the expressions derived. (Xu)... 

There is, however, a fundamental contradiction. We have stated that opposite charges attract and hke charges repel, and that electrons all have a negative charge. If this is true, then why don t collections of valence electrons explode into flying showers of electrons instead of settling into strong chemical bonds ... 

The algebraic signs of q and q determine whether the force is attractive or repulsive. If q and q2 are like charges, they repel F > 0), whereas opposite charges attract F < 0). In our applications to atomic and molecular structure, it is clumsy and unnecessary to carry the constant 47T6o. We will instead write Coulomb s law in gaussian electromagnetic units, whereby... 

Because opposite charges attract, cations and anions should attract one another. This is exactly what happens when an ionic bond is formed. In the case of pyrite, the iron cations and sulfur anions attract one another to form an ionic compound. 

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