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Q: chemistry ( Answered,   0 Comments )
Subject: chemistry
Category: Science
Asked by: darrcour-ga
List Price: $2.00
Posted: 08 Oct 2003 09:54 PDT
Expires: 07 Nov 2003 08:54 PST
Question ID: 264249
what is the relationship between the ionization energy and the
increasing atomic number within a period and relationship between
atomic radius and increasing atomic number within a period up to element 36?
Subject: Re: chemistry
Answered By: xargon-ga on 10 Oct 2003 16:57 PDT
The trend of the ionization energy is increasing within each period
(row) and decreasing within each group (column).  This is due to the
fact that the outer shell fills with electrons across the period; the
noble gasses generally have larger values for ionization as their
valence shells are full and stable.  Moving down the periodic table,
full shells of electrons beneath the valence shell provide shielding
from the nucleus, causing the ionization energy to decrease.

A table of the energies up to element 36 is provided by the chemistry
department of Queen's University (at the bottom I have also provided
several other interesting links containing tables and graphs of the
complete periodic table).

Concerning atomic radius, the trend across a period is decreasing and
down a group is increasing.  This is due to the increase in nuclear
charge with no change to the shielding between the valence shell and
nucleus.  In a group, the "effective nuclear charge" remains constant
(because the inner electrons maintain a proportional shielding effect)
allowing for atomic radius to actually increase slightly (due to
larger nucleii and larger electron shells).

An excellent graphic of the entire periodic table is provided by MIT,
showing the radial trend in both directions (additional links are also
provided below).

I hope this helps you out!  Thank you for using Google Answers.



Dr. Michael Blaber, Florida State University [ionization energy]

Introduction to Chemistry, Dartmouth College [ionization energy]

Daniel High School [ionization energy--complete periodic table]

Intro to Chemistry, Oklahoma State University [atomic radius]

Chemweb, University College Cork

Search Terms Used:

"ionization energy" "atomic number"

"atomic radius" "atomic number" trend
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