Noble gases electronegativity

Stable noble gas compounds are restricted to those of xenon. Most of these compounds involve bonds between xenon and the most electronegative elements, fluorine and oxygen. More exotic compounds containing Xe—S, Xe—H, and Xe—C bonds can be formed under carefully controlled conditions, for example in solid matrices at liquid nitrogen temperature. The three Lewis structures below are examples of these compounds in which the xenon atom has a steric munber of 5 and trigonal bipyramidal electron group geometry. 

The method has been confined to main-group compounds presumably because of irregularities expected with unsymmetrical charge distributions in transition metal ions. The noble gas compounds remain outside the scope of the method because of the way in which electronegativity is defined (atom compactness relative to interpolated noble atom compactness). The main weakness of the method when applied to fluorides is in the somewhat arbitrary choice of fluorine bond energies. 

True, except for the group 18 noble gas elements, which are not assigned an electronegativity number. The trend is that electronegativity decreases with an increasing number of shells down any one atomic group (vertical column) of the periodic table. 

The strength of this attraction is based on two factors the distance from the nucleus to the outermost electrons, and the valence electron pattern. The distance factor is a function of the fact that the closer the nucleus is to the outer electrons, the greater the power of the nucleus in pulling in other electrons. This is similar to the observation that a magnet works best when close to an object. As the valence electron pattern approaches the noble gas valence electron pattern, the more effective the element is at attracting electrons. Noble gases have virtually no electronegativity, as they rarely react. 

Se, S, Cl. Se has the lowest electronegativity because it has the largest atomic size, meaning that its nucleus is farther from the outer electrons. Chlorine is closer to having the noble gas valence electron pattern than is sulfur. 

Nonmetals have higher electronegativity because they are gainers of electrons, this being their best pathway to achieving a noble gas valence electron pattern. 

The Pearson concept of hard and soft acids and bases considers the number of electrons in the outer shell. Elements with a saturated outer shell and low tendency for polarization (noble gas configuration) are called hard acids, while elements with only partially filled outer shell, low electronegativity, and high tendency for polarization are soft acids. 

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