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

Verified step by step guidance

1. Identify the positions of Arsenic (As) and Fluorine (F) on the periodic table. Arsenic is in Group 15 and Period 4, while Fluorine is in Group 17 and Period 2.
2. Understand the concept of first ionization energy: it is the energy required to remove the most loosely held electron from an atom of an element in its gaseous state.
3. Recognize the trend in ionization energy across a period: Ionization energy generally increases as you move from left to right across a period due to increasing nuclear charge and decreasing atomic radius.
4. Recognize the trend in ionization energy down a group: Ionization energy generally decreases as you move down a group because the outer electrons are farther from the nucleus and more shielded by inner electrons.
5. Compare the trends: Since Fluorine is to the right and in an earlier period compared to Arsenic, it generally has a higher first ionization energy.

Key Concepts

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom in its gaseous state. It is a key indicator of how strongly an atom holds onto its electrons. Generally, ionization energy increases across a period in the periodic table due to increasing nuclear charge and decreases down a group due to increased distance from the nucleus and electron shielding.

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 (like fluorine) typically have higher ionization energies than those on the left (like arsenic) due to their greater effective nuclear charge and smaller atomic radii.

Comparison of Elements

When comparing elements like arsenic (As) and fluorine (F), it is essential to consider their positions in the periodic table. Fluorine, being a halogen in Group 17, has a higher electronegativity and a stronger attraction for its electrons compared to arsenic, which is in Group 15. This results in fluorine having a significantly higher first ionization energy than arsenic.