The first ionization potentials for calcium and barium are 589.7 kJ/mol and 502.8 kJ/mol. What is the predicted first ionization potential for strontium?
A) 546.3 kJ/mol
B) 1092.5 kJ/mol
C) 86.9 kJ/mol
D) 435.7 kJ/mol
E) 588 kJ/mol

Question

Quizplus · Accepted Answer

There is a trend in first ionization energies (IE) within a group of the periodic table (elements with the same valence electron configuration) where IE generally increases as you go from left to right. So, based on the trend we can expect strontium to have a higher IE than calcium but lower than barium. Therefore, the predicted first ionization potential for strontium would fall between the values for calcium and barium. Taking the average of the two values gives:

(589.7 kJ/mol + 502.8 kJ/mol)/2 = 546.3 kJ/mol

Therefore, the predicted first ionization potential for strontium is 546.3 kJ/mol, which corresponds to choice A.

The First Ionization Potentials for Calcium and Barium Are 589