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Date: 19-1-2018
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Date: 20-12-2018
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Date: 25-11-2018
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The atomic radius increases down the group. Notice that beryllium has a particularly small radius compared with the rest of the group.
The radius of an atom is governed by
Compare the electron configurations of beryllium and magnesium:
In each case, the two outer electrons experience a net charge of +2 from the nucleus. The positive charge on the nucleus is balanced by the negativeness of the inner electrons.
This is true for all the atoms in Group 2. The only factor influencing the size of the atom is therefore the number of layers of inner electrons that fit around the atom. More layers of electrons take up more space, due to electron-electron repulsion, so atoms are larger down the group.
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علامات بسيطة في جسدك قد تنذر بمرض "قاتل"
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أول صور ثلاثية الأبعاد للغدة الزعترية البشرية
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مستشفى العتبة العباسية الميداني في سوريا يقدّم خدماته لنحو 1500 نازح لبناني يوميًا
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