Electrons electric charge

The positive or negative charge (commonly symbohzed by Q or g) on a molecule, radical, or particle resulting from the deficient or excess accumulation of electrons. Electric charge need not be an integer value. The SI unit coulomb (abbreviated C) equals the quantity of electricity transferred by an electric current of 1 ampere over the period of 1 second. 

The three particles that make up atoms are protons, neutrons, and electrons. Protons and neutrons are heavier than electrons and reside in the "nucleus," which is the center of the atom. Protons have a positive electrical charge, and neutrons have no electrical charge. Electrons are extremely lightweight and are negatively charged. They exist in a cloud that surrounds the atom. The electron cloud has a radius 10,000 times greater than the nucleus. 

An electron carries one unit of negative electrical charge (Figure 46.2). Its mass is about 1/2000 that of a proton or neutron. Therefore, very little of the mass of an atom is made from the masses of the electrons it contains, and generally the total mass of the electrons is ignored. For example, an atom of iron has a mass of 56 atomic units (au also called Daltons), of which only about 0.02% is due to the 26 electrons. Thus an iron atom (Fe ) is considered to have the same mass as a doubly charged cation of iron (Fe " ), even though there is a small mass difference. 

The electron carries one negative electric charge and has a mass only 1/2000th that of a proton. 

Each proton is about 2000 times heavier than an electron, and its mass is one atomic unit. Importantly, it also carries one unit of positive electric charge (Figure 46.2). The proton is very... 

A neutron is characterized by having no electrical charge but has one unit of atomic mass, the same as that of a proton (Figure 46.2). Neutrons, like protons, reside in the atomic nucleus and contribute to the mass of the atom. The chemistry of an atom, like its size, is determined by the electrons in the atom. The mass of the atom is characterized mainly by the total number of neutrons and protons in the nucleus (atomic binding energies are ignored in this discussion). For mass spectrometric purposes of measurement, it is the mass that is important in establishing m/z values. 

Molecules can interact with energetic electrons to give ions (electron ionization, El), which are electrically charged entities. The interaction used to be called electron impact (also El), although no actual collision occurs. 

Polarizability Attraction. AU. matter is composed of electrical charges which move in response to (become electrically polarized in) an external field. This field can be created by the distribution and motion of charges in nearby matter. The Hamaket constant for interaction energy, A, is a measure of this polarizability. As a first approximation it may be computed from the dielectric permittivity, S, and the refractive index, n, of the material (15), where is the frequency of the principal electronic absorption... 

When two conducting phases come into contact with each other, a redistribution of charge occurs as a result of any electron energy level difference between the phases. If the two phases are metals, electrons flow from one metal to the other until the electron levels equiUbrate. When an electrode, ie, electronic conductor, is immersed in an electrolyte, ie, ionic conductor, an electrical double layer forms at the electrode—solution interface resulting from the unequal tendency for distribution of electrical charges in the two phases. Because overall electrical neutrality must be maintained, this separation of charge between the electrode and solution gives rise to a potential difference between the two phases, equal to that needed to ensure equiUbrium. 

Membrane Efficiency The permselectivity of an ion-exchange membrane is the ratio of the transport of electric charge through the membrane by specific ions to the total transport of electrons. Membranes are not strictly semipermeable, for coions are not completely excluded, particularly at higher feed concentrations. For example, the Donnan eqmlibrium for a univalent salt in dilute solution is ... 

The work on colour centres outlined in Section 3.2.3.1, much of it in the 1930s, and its consequences for understanding electrically charged defects in insulating and semiconducting crystalline materials, helped to stimulate ceramic researches in the electrical/electronic industry. The subject is enormous and here there is space only for a cursory outline of what has happened, most of it in the last 80 years. 

ION An isolated electron or positron, or an atom or molecule, which by loss or gain of one or more electrons has acquired a net electric charge. 

Electrostatic theory proposes that two materials are held together by electrical charges. Electrons are transported between the adhesive and the substrate forming... 

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