Which of the following atoms has the lowest ionization potential?
A. ²₄He
B. ⁷14N
C. ⁸16O
D. ¹⁸40Ar
E. ⁵⁵133Cs
Solution:
Ionization potential: the energy required to to remove the valence (outermost) electron from an atom
It is minimum for atoms (alkali metals) which have weakly bound electrons and higher for the noble gases which have closed shells.
²₄He and Argon ⁸40Ar are noble gases which have a closed-shell valence electron configuration.
⁷14N → 1s2 2s2 2p6 3s2 3p2 (2 outermost electrons, almost a full orbital)
⁸16O → 1s2 2s2 2p64 3s2 3p2 (4 outermost electrons, almost a full orbital)
⁵⁵133Cs has the highest atomic number and hence a lot of electrons. The valence electron is far from the nucleus (weakly bound), thus it needs the lowest ionization potential to remove it.
Answer: E
A. ²₄He
B. ⁷14N
C. ⁸16O
D. ¹⁸40Ar
E. ⁵⁵133Cs
(GR9677 #39)
Ionization potential: the energy required to to remove the valence (outermost) electron from an atom
It is minimum for atoms (alkali metals) which have weakly bound electrons and higher for the noble gases which have closed shells.
²₄He and Argon ⁸40Ar are noble gases which have a closed-shell valence electron configuration.
⁷14N → 1s2 2s2 2p6 3s2 3p2 (2 outermost electrons, almost a full orbital)
⁸16O → 1s2 2s2 2p64 3s2 3p2 (4 outermost electrons, almost a full orbital)
⁵⁵133Cs has the highest atomic number and hence a lot of electrons. The valence electron is far from the nucleus (weakly bound), thus it needs the lowest ionization potential to remove it.
Answer: E
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