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Date: 13-11-2018
938
Date: 1-2-2018
1256
Date: 31-1-2018
970
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Physical properties of Group 18 elemnts
Some physical properties of the group 18 elements are listed in Table 1.1.
Table 1.1 Some physical properties of the group 18 elements (noble gases).
Of particular significance is the fact that the noble gases have the highest ionization energies of the elements in their respective periods (Figure 1.15), but there is a decrease in values on descending the group. The extremely low values of Δand ∆vapHo correspond to the weak van der Waals interactions between the atoms, and the increase in values of ∆vapHo down the group is due to increased interatomic interactions as atomic size and polarizability increase. The properties of He deserve special note; it can diffuse through rubber and most glasses. Below 2.18 K, ordinary liquid 4He (but not 3He) is transformed into liquid He(II) which has the remarkable properties of a thermal conductivity 600 times that of copper, and a viscosity approaching zero; it forms films only a few hundred atoms thick which flow up and over the side of the containing vessel.
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دراسة يابانية لتقليل مخاطر أمراض المواليد منخفضي الوزن
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اكتشاف أكبر مرجان في العالم قبالة سواحل جزر سليمان
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المجمع العلمي ينظّم ندوة حوارية حول مفهوم العولمة الرقمية في بابل
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