2.29987 nearest hundredth
2 answers:
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Answer: A) Ar
Explanation: Argon [Ar] has an atomic no of 18 and the electronic configuration is:
Ar :
Chlorine [Cl] has atomic no of 17 and thus the electronic configuration is :
Cl :
Magnesium [Mg] has atomic no of 12 and thus the electronic configuration is :
Mg :
Sodium has atomic no of 11 and thus the electronic configuration is :
Cl :
As we move across a period the number of electrons are being added to the same shell but the number of protons increases, thus the electrons are being tightly held and thus the atomic radius keeps on decreasing.
Thus the smallest atom would have a tightly bound electron nearer to the nucleus. As argon is the last element of the period, it is the smallest in the period and thus largest amount of energy will be required to remove the outermost electron.