Choose the element with the higher first ionization energy from each pair. c. As or At

Key Concepts

Ionization Energy

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. It is a key factor in determining an element's reactivity and is influenced by the atomic size and the effective nuclear charge. Generally, ionization energy increases across a period and decreases down a group in the periodic table.

Periodic Trends

Periodic trends refer to the predictable patterns observed in the properties of elements as you move across or down the periodic table. For ionization energy, elements on the right side of the table tend to have higher ionization energies than those on the left, while elements higher up in a group have higher ionization energies than those lower down due to decreased electron shielding.

Comparison of Elements

When comparing elements like arsenic (As) and astatine (At), it is essential to consider their positions in the periodic table. Astatine is located below arsenic in Group 17, which typically results in a lower ionization energy due to increased atomic size and electron shielding. Understanding these positions helps predict which element will have a higher first ionization energy.