Question

which of the following will have a lower ionization energy than scandium (sc)?
helium (he)
titanium (ti)
magnesium (mg)
calcium (ca)

Explanation:

Step1: Recall ionization energy trends

Ionization energy generally increases across a period and decreases down a group.

Step2: Analyze each element

• Helium (He) is a noble gas with a full valence shell, high ionization energy.
• Titanium (Ti) is to the right of Sc in the same period, higher ionization energy.
• Magnesium (Mg) is in a lower period but has a stable electron configuration (\(3s^{2}\)), higher ionization energy than Ca.
• Calcium (Ca) is below Sc in the periodic table. As we move down a group, ionization energy decreases.

Answer:

Calcium (Ca)