Electron charge, unit

The field ( ) is the so-called reaction field which is due in the present case to the ground state dipole of the solute, fx(s), and is given (in A-2 and electron charge units) by (Ref. 3)... 

Vo is given in A electron charge units, r is the closest distance (in A) between the grid points to the indicated solute atom. 

Before beginning a discussion of nuclei and their properties, we need to understand the environment in which most nuclei exist, that is, in the center of atoms. In elementary chemistry, we learn that the atom is the smallest unit a chemical element can be divided into that retains its chemical properties. As we know from our study of chemistry, the radii of atoms are approximately 1-5 x 10-10 m, or 1 -5 A. At the center of each atom we find the nucleus, a small object (r 1-10 x 10-15 m) that contains almost all the mass of the atom (Fig. 1.1). The atomic nucleus contains Z protons, where Z is the atomic number of the element under study, Z being number of protons and is thus the number of positive charges in the nucleus. The chemistry of the element is controlled by Z in that all nuclei with the same Z will have similar chemical behavior. The nucleus also contains N neutrons, where N is the neutron number. Neutrons are uncharged particles with masses approximately equal to the mass of a proton ( 1 u). Each proton has a positive charge equal to that of an electron. The overall charge of a nucleus is +Z electronic charge units. 

Most of the atom is empty space in which the electrons surround the nucleus. (Electrons are small, negatively charged particles with a charge of — 1 electronic charge units and a mass of about 1/1840 of the proton mass.) The negatively charged electrons are bound by an electrostatic (Coulombic) attraction to the positively charged nucleus. In a neutral atom, the number of electrons in the atom equals the number of protons in the nucleus. 

A related unit, normality (N), refers to the number of equivalents of a chemical per liter of water. An equivalent is the amount of a chemical that either possesses, or is capable of transferring in a given reaction, 1 mol of electronic charge. If a chemical has two electronic charge units per molecule, 1 mol of the chemical constitutes two equivalents [e.g., a mole of sulfate (SO2-) is equal to two equivalents, and a one molar (1 M) solution of sodium sulfate (Na2S04) is two normal (2 N)]. 

Fig. 2. Configuration, geometry, and partial atomic charges for the cyclic hydrogen bonded dimer of acetic acid. The partial atomic charges in brackets are the polarized charges for the H4 and Oiv atoms, in the dimer configuration shown. The partial charges should be divided by 1000 to obtain electronic charge units.

At this point it is possible to compute, for each bond, a very important quantity the polarity parameter Oj, which is a measure (in electronic charge units) of the positive electric charge transferred, in the 7th bond, from the atom Aj to the atom B. This parameter, defined by the equation ... 

Figure 4 Solid line shows pair correlation function obtained via LFT for a liquid composed of polyballs of radius 83 nm in water at room temperature. The charge per polyball is 2000 electron charge units, and the number density of polyballs is 1.0 x I0 cm . The concentration of impurity ions is 9.2 x 10 cm This figure is taken from Ref. 50, where further details of the calculation are given. The two dashed lines refer to results obtained u.sing approximate pair potentials which are described in Ref. 50...

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