Anita Akweshie
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definition of atomic radius
a measure of the size of an atom
half the distance between the two nuclei of two covalently bonded atoms
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atomic radii trend across a Period
decrease
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atomic radii trend down a Group
increase
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explanation of atomic radii trends
Electron shell theory
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why does atomic radii decrease across a period
increased positive nuclear charge, greater pull of electrons
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why does atomic radii increase down a group
increased number off shells, increasing shielding from nucleus, weaker pull of nucleus
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atomic radii increases sharply between
the noble gas at the end of one period and the alkali metal of the next period
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explanation for sharp increase between noble gas and alkali metal
alkali metals have one extra principle quantum shell, increased shielding
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definition of ionic radii
a measure of the size of an ion
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ionic radii increase with
increasing negative charge
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ionic radii decrease with
increasing positive charge
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formation of negative ions
accepting extra electrons only
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which electrons are held weakly to the nucleus
the outermost electrons
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the larger the ionic radius, the
greater the negative charge
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formation of positive ions
losing electrons only
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the smaller the ionic radius, the
greater the positive charge
