Identify the element that has the lower ionization energy

CBSE Class 10 CBSE Class 10 Science
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1

Identify the element that has the lower ionization energy in each pair of the following and mark it with a symbol tick mark.
(i) Mg, Na (ii) Li, O (iii) Br, F (iv) K, Br

2

i) Mg or Na : Na has low ionization energy. Since Mg, Na are in same period : ionization energy increases left to right. Na is left to Mg. So Na has lower ioniza¬tion energy.
ii) Li or O : Li has lower ionization energy. Li is left to ‘O’ in a period.
iii) Br or F : Bromine has lower ionization energy. Because these are in group. IE decreases from top to bottom. Bromine is at bottom. So it has lower IE.
iv) K or Br : K’ has lower ionisation energy. Since it is left to the period.