TPR Metallic Character Question

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So from TPR Review Book

The first ionization energy of potassium is 0.41 MJ/mol. The first ionization of barium (Ba) is 0.50 MJ/mol. Therefore:

A. barium is more metallic than potassium
B. potassium is more metallic than barium
C. barium has a greater electron affinity than potassium
D. potassium has a greater electron affinity than barium


The answer is B but why? Highest metallic character is lower left on the Periodic Table which would clearly point to barium. Yes, lower first energy means higher metallic character. Are you supposed to just ignore the periodic trend then or what? Clarification would be great.

 

[fluoropHore]

So from TPR Review Book

The first ionization energy of potassium is 0.41 MJ/mol. The first ionization of barium (Ba) is 0.50 MJ/mol. Therefore:

A. barium is more metallic than potassium
B. potassium is more metallic than barium
C. barium has a greater electron affinity than potassium
D. potassium has a greater electron affinity than barium


The answer is B but why? Highest metallic character is lower left on the Periodic Table which would clearly point to barium. Yes, lower first energy means higher metallic character. Are you supposed to just ignore the periodic trend then or what? Clarification would be great.

I would reason to guess because K has an easier time getting rid of its lone outer electron (1s) , whereas its harder to take away Ba's 2s outer shell electron. Taking 1 away would leave 1s, an unstable shell.

 

[fluoropHore]

Yes periodic trends are important, but remember to look at shell stability.