Choose the element with the higher first ionization energy from each pair. b. Li or K

Verified step by step guidance

1. Understand that the first ionization energy is the energy required to remove the outermost electron from a neutral atom in the gaseous state.
2. Recall that ionization energy generally increases across a period (from left to right) and decreases down a group (from top to bottom) in the periodic table.
3. Identify the position of the elements in the periodic table: Lithium (Li) is in period 2, group 1, and Potassium (K) is in period 4, group 1.
4. Recognize that both elements are in the same group (alkali metals), so the trend of decreasing ionization energy down the group applies.
5. Conclude that since Li is above K in the same group, Li has a higher first ionization energy than K.

Key Concepts

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom or ion 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 on the periodic table and decreases down a group, due to the increasing distance of the outer electrons from the nucleus and increased 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 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. Understanding these trends helps in predicting the behavior of elements.

Lithium vs. Potassium

Lithium (Li) and potassium (K) are both alkali metals, but they are located in different periods of the periodic table. Lithium is in the second period, while potassium is in the fourth. Due to its higher position, lithium has a smaller atomic radius and less electron shielding, resulting in a higher first ionization energy compared to potassium, which has more electron shells and a weaker hold on its outermost electron.