Choose the element with the higher first ionization energy from each pair. b. Na or Rb

Verified step by step guidance

1. Step 1: Understand the concept of ionization energy. Ionization energy is the energy required to remove an electron from a gaseous atom or ion. The first ionization energy refers to the energy needed to remove the first electron from a neutral atom.
2. Step 2: Remember that ionization energy generally increases from left to right across a period (row) in the periodic table and decreases from top to bottom within a group (column). This is because as you move from left to right, the atomic radius decreases, making the electrons closer to the nucleus and harder to remove. As you move down a group, the atomic radius increases, making the outermost electrons easier to remove.
3. Step 3: Locate Sodium (Na) and Rubidium (Rb) on the periodic table. Both elements are in the same group (Group 1: Alkali Metals), but Sodium is above Rubidium.
4. Step 4: Apply the trend of ionization energy within a group. Since ionization energy decreases as you move down a group, Sodium (Na), being higher up in the group, should have a higher first ionization energy than Rubidium (Rb).
5. Step 5: Therefore, Sodium (Na) has a higher first ionization energy than Rubidium (Rb).

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.

Sodium (Na) vs. Rubidium (Rb)

Sodium (Na) and Rubidium (Rb) are both alkali metals, with sodium located higher in Group 1 of the periodic table than rubidium. Due to its higher position, sodium has a smaller atomic radius and less electron shielding, resulting in a stronger attraction between the nucleus and its outermost electron. Consequently, sodium has a higher first ionization energy compared to rubidium, which is more easily ionized.