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The trend and reasons of melting point boiling point electronegativity solubility...

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hoorfatima | Student, Undergraduate | eNotes Newbie

Posted April 5, 2010 at 11:05 PM via web

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The trend and reasons of melting point boiling point electronegativity solubility ionization energy electron affinity in periodic table.

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hnystrom | High School Teacher | (Level 1) Assistant Educator

Posted July 11, 2010 at 7:39 PM (Answer #1)

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The question is confusing and not well stated (soluability? in what?)but I will try to answer part of it.  In general as one goes across the periodic table in a row one is adding electrons to an exisiting orbital or shell structure.  At the same time the charge in the nucleus is building up.  This tends to increase the force on the outer electrons which affects the size of the atom.  In moving down a column one is adding electrons to a new shell.  The new electrons are added further out from the nucleus while the nuclear charge is screened somewhat by the electrons in the lower shells.  This tends to decrease the force on the outer electrons.

Electronegativity is the tendency to attract new electrons to form ions.  As we move along a row the charge in the nucleus builds up, so electrons are attracted by a stronger and stronger force leading to increase in EN.  As we go down a column we add electrons further and further from the nucleus so the EN decreases because they are held by a weaker force than the atom above it.

The ionization energy is the energy it takes to pull off an electron.  As we can guess from above, it the nuclear charge is greater across a row it takes more and more energy to pull an electron off an atom.  IE increase across a row.  It decreases down a column because the force is weaker.

The electron affinity shows the same tendencies as the IE above.

When we get to the last colum there is an abrupt change in EN and EA.  These elements, the noble gases, have completely filled shells.  The EA and EN not only decreases, it drops to zero because it is partically impossible to add an additional electron.  There are a few compounds formed of those lower on the column such as  Xe with highly reactive elements such as O2 and F2.  XeF4 was the first artifically produced noble gas compound.

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