Trends in modern periodic table: Size …

DEFINE ATOMIC SIZE (ATOMIC RADIUS) - DEFINITION

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Atomic Size (Atomic Radius) is the

distance between the nucleus and valence shell.

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METALLIC AND NON-METALLIC PROPERTIES - DEFINITION

<article>The tendency of an element to lose electrons and form positive ions (cations) is called electropositive or metallic character. The tendency of an element to accept electrons to form an anion is called its non-metallic or electronegative character. In each period, metallic character of elements decreases as we move to the right. Elements to the left of the periodic table have a pronounced metallic character while those to the right have a non-metallic character. Conversely, non-metallic character increases from left to right.
As we move down the group the number of shells increases. This causes the effective nuclear charge to decrease due to the outer shells being further away: in effect the atomic size increases. The electrons of the outermost shell experience less nuclear attraction and so can lose electrons easily thus showing increased metallic character.</article>