Electrical charges electrically neutral atoms

Since the nucleus has positive charge, it attracts electrons (each with negative charge). If a nucleus attracts the number of electrons just equal to the nuclear charge, an electrically neutral atom is formed. Consider a nucleus containing two protons, a helium nucleus. When the helium atom has two electrons as well (2— charge), an electrically neutral helium atom results ... 

Ions are derived from electrically neutral atoms (or groups of atoms) but differ from them in that they possess an electrical charge. This charge is positive for the hydrogen ion and for ions derived from metals (or nonmetallic groups such as NH4) and negative for ions derived from nonmetals or acidic radicals. 

It is important to understand that the atomic charges refer to atoms that are not spherical. Consequently the centroid of electronic charge of an atom does not in general coincide with the nucleus, and each atom therefore has an electric dipole moment—or, more generally, an electric dipolar polarization (since only the dipole moment of electrically neutral atoms is origin independent). 

Electrically neutral atoms with nuclear charge Z > I are not hydrogenlike, but have inure than a single orbital electron. With more than one electron in an atom, it is necessary to determine the relationship of one... 

Count the total number of valence electrons contributed by the electrically neutral atoms. If the species being considered is an ion, add one electron to the total for each negative charge subtract one for each positive charge. 

Mass spectrometry is based on the physical properties of the atomic nucleus. The atomic nucleus of any chemical element consists of protons and neutrons. In an electrically neutral atom the number of positively charged protons in the nucleus equals the number of negatively charged electrons in the shells. The number of protons (Z = atomic number) determines the chemical properties and the place of the element in the periodic table of the elements. The atomic number Z of a chemical element is given as a subscript preceding the elemental symbol (e.g., jH, gC, 17CI, 2eF or 92 )-Besides the protons, uncharged neutrons with nearly the same mass in comparison to the protons (m = 1.67493 x 10 kg versus nip = 1.67262 x 10 kg) stabilize the positive atomic nucleus. In contrast to the mass of the protons and neutrons in the nucleus, the mass of the electrons is relatively small at = 9.10939 x 10 kg. 

Atoms are composed of a positively charged concentrated center called the nucleus surrounded hy negatively charged electrons. The nucleus contains positively charged protons and zero-charged neutrons. In electrically neutral atoms there are equal numbers of protons and electrons. 

As discussed in detail in Chapter 5, an atom consists of a very small, very dense, positively charged nucleus surrounded by a diffuse distribution of negatively charged particles called electrons. The number of positive charges in the nucleus defines the identity of the element to which the atom corresponds. Electrically neutral atoms contain the same number of electrons outside the nucleus as positive charges (protons) within the nucleus. Ions are formed when neutral atoms lose or gain electrons. An Na+ ion is formed when a sodium atom loses one electron, and a Cl ion is formed when a chlorine atom gains one electron. 

Every atom has one nucleus, which has most of the mass of the atom and has a positive electric charge of Z units. Z is called the atomic number. In an electrically neutral atom there are Z electrons in motion about the nucleus. 

Chapter 2 shows you that elements are arranged in the periodic table in order of increasing atomic number. The atomic number of an element equals the number of protons in the nucleus of an atom of that element. The atomic number identifies an element. The atomic number appears above the symbol for each element in the periodic table. Any atom with only 1 proton in its nucleus is a hydrogen atom, the element with an atomic number of 1. The atomic number of carbon, for example, is 6. Every atom of carbon has 6 protons in its nucleus. Likewise, any atom that has 6 protons in its nucleus is a carbon atom. If an atom has 7 protons in its nucleus, it s not carbon it s the next element, nitrogen. For a neutral atom, the atomic number also equals the number of electrons about the nucleus. An electrically neutral atom must have the identical number of positive and negative charges. 

In an electrically neutral atom, or an atom in which the number of positive charges equals the number of negative charges, the number of protons must equal the number of electrons. Thus, for a neutral atom, the atomic number is not only the number of protons in an atom, but it is also the number of electrons. An atom may gain and lose electrons, and that is why the number of electrons is not an identifying characteristic for an element like the number of protons is. An atom caimot lose or gain protons. The particle that results from... 

The number of electrons in an electrically neutral atom is easy to determine—it is equal to the number of protons. Protons and electrons have the same magnitude of charge, just opposite signs, so equal numbers of protons and electrons will give an atom a net charge of zero, which is what electrically neutral means. 

The individual atom is formed by a positively charged nucleus composed of protons and neutrons surrounded by a negatively charged electron cloud. An electrically neutral atom contains equal numbers of electrons and protons. If an electrically neutral atom absorbs or emits one or more electrons, a negative ion or positive ion, respectively, is created. 

The reaction that takes place at the sacrificial anode is the conversion of electrically neutral atoms to positively charged ions released to a plating bath ... 

The multiple energetic collisions cause molecules to break apart, eventually to form only atoms, both charged and neutral. Insertion of sample molecules into a plasma discharge, which has an applied high-frequency electric field, causes the molecules to be rapidly broken down into electronically excited ions for all of the original component atoms. 

Zeolites are crystalline alumina-silicates having a regular pore structure. Their basic building blocks are silica and alumina tetrahedra. Each tetrahedron consists of silicon or aluminum atoms at the center of the tetrahedron with oxygen atoms at the comers. Because silicon and aluminum are in a +4 and +3 oxidation state, respectively, a net charge of -1 must be balanced by a cation to maintain electrical neutrality. 

At any interface between two different phases there will be a redistribution of charge in each phase at the interface with a consequent loss of its electroneutrality, although the interface as a whole remains electrically neutral. (Bockris considers an interface to be sharp and definite to within an atomic layer, whereas an interphase is less sharply defined and may extend from at least two molecular diameters to tens of thousands of nanometres the interphase may be regarded as the region between the two phases in which the properties have not yet reached those of the bulk of either phase .) In the simplest case the interface between a metal and a solution could be visualised as a line of excess electrons at the surface of the metal and an equal number of positive charges in the solution that are in contact with the metal (Fig. 20.2). Thus although each phase has an excess charge the interface as a whole is electrically neutral. 

As you probably know, an atom consists of a dense, positively charged nucleus surrounded at a relatively large distance by negatively charged elections (Figure 1.2). The nucleus consists of subatomic particles called neutrons, which are electrically neutral, and protons, which are positively charged. Because an atom is neutral... 

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