Electrons in atomic orbitals

In Fig. 1 there is indicated the division of the nine outer orbitals into these two classes. It is assumed that electrons occupying orbitals of the first class (weak interatomic interactions) in an atom tend to remain unpaired (Hund s rule of maximum multiplicity), and that electrons occupying orbitals of the second class pair with similar electrons of adjacent atoms. Let us call these orbitals atomic orbitals and bond orbitals, respectively. In copper all of the atomic orbitals are occupied by pairs. In nickel, with ou = 0.61, there are 0.61 unpaired electrons in atomic orbitals, and in cobalt 1.71. (The deviation from unity of the difference between the values for cobalt and nickel may be the result of experimental error in the cobalt value, which is uncertain because of the magnetic hardness of this element.) This indicates that the energy diagram of Fig. 1 does not change very much from metal to metal. Substantiation of this is provided by the values of cra for copper-nickel alloys,12 which decrease linearly with mole fraction of copper from mole fraction 0.6 of copper, and by the related values for zinc-nickel and other alloys.13 The value a a = 2.61 would accordingly be expected for iron, if there were 2.61 or more d orbitals in the atomic orbital class. We conclude from the observed value [Pg.347]

Electron configuration The arrangement of electrons in atomic orbitals. 

The correct answer is (C). Paramagnetism can be seen in atoms with unpaired electrons. Hund s rule allows us to predict the pairing of electrons in atomic orbitals, and, therefore, the magnetic properties of the atom. 

The valence bond method is older and follows quite naturally the notion of two atoms combining to form a molecule by sharing of electrons in atomic orbitals. In this section, we describe bonding in diatomic molecules. 

In the broadest sense, an electron configuration is any description of the complete distribution of electrons in atomic orbitals. Although this can mean either an orbital diagram or the shorthand notation, this text will follow the common convention of referring to only the shorthand notation as an electron configuration. For example,... 

Only electrons in atomic orbitals are involved in the breaking and forming of bonds. 

Equation [23d] has a nice interpretation. The energy of an electron in atomic orbital x is equal to the negative of its Mulliken electronegativity, (/ + A)/2, corrected for charge build-up on atom A, Q. Yaai to which it belongs, corrected in turn for the number of electrons in the x orbital itself (1 - P ), and then corrected by the Madelung terms (Coulomb attractions and repulsions) located throughout the molecule, Q/jY,uj-... 

Tin, Sn, has an atomic number of 50 thus we must place fifty electrons in atomic orbitals. We must also remember the total electron capacities of orbital types s, 2 p, 6 d, 10 and /, 14. The electron configuration is as follows ... 

The TT electrons are placed in molecular orbitals according to the same rules that govern the placement of electrons in atomic orbitals (Section 1.2) the aufbau principle (orbitals are filled in order of increasing energy), the Pauli exclusion principle (each... 

Equation (2.40b) follows from substitution of Eq.(2.39b) into Eq.(2.40a). Equation (2.39d) is an important result. Interpretation of as the number of electrons in atomic orbital k is becoming more evident, if one realizes that the total number of electrons has the following relationship to... 

The probability of finding an electron in atomic orbital t is given by the diagonal part of the bond-order population density Therefore the energy density of... 

Since a magnetic field is produced by an electric current, which consists in a flow of electrons along a conductor, the motion of free electrons in atomic orbits may fairly be supposed to give rise to a similar effect. It is also a reasonable hypothesis that the spin of an electron should be associated with a magnetic moment, and so it proves. 

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