Atoms with more than two electrons atomic properties and periodic trends

Atoms with more than two electrons atomic properties and periodic trends 

The energy difference between valence shell. y and p electrons in an atom is of secondary importance for our description of a molecule if the atom uses both s and p electrons for bond formation, or if we describe the molecule using molecular orbitals formed from sp hybridized atomic orbitals. The mean valence electron ionization energies may therefore be used to define a set of electronegativity coefficients. The magnitudes of these electronegativity coefficients are found to increase across a period, and - with a few exceptions - to decrease down a group. 

Finally we provide the basis for later discussions of the charge distributions in molecules by defining the electric dipole moment of an atom and showing how it may be calculated from the charge density. 

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