Answer:
The electron configurations for Sodium (Na), Francium (Fr), Fluorine (F), and Chlorine (Cl) are as follows:
- Sodium (Na): 1s² 2s² 2p⁶ 3s²
- Francium (Fr): 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p⁶ 7s¹
- Fluorine (F): 1s² 2s² 2p⁶
- Chlorine (Cl): 1s² 2s² 2p⁶ 3s² 3p⁶
Now, let's explain the differences in ionization energy as it relates to the periodic trend. Ionization energy is the energy required to remove an electron from an atom. The key factor influencing ionization energy is the distance of the outermost electrons from the nucleus and the effective nuclear charge experienced by those electrons.
1. **Sodium (Na)**:
- Sodium is in the alkali metal group (Group 1) on the periodic table.
- It has a relatively low ionization energy because it has a single valence electron in the 3s orbital, which is relatively far from the nucleus. It is easy to remove this electron.
2. **Francium (Fr)**:
- Francium is an alkali metal located at the bottom of Group 1.
- It has the lowest ionization energy of all elements because it is located in the seventh period, and its outermost electron is farthest from the nucleus.
3. **Fluorine (F)**:
- Fluorine is in the halogen group (Group 17).
- It has a high ionization energy because it needs to remove an electron from a filled 2p subshell. The electrons in this subshell are relatively close to the nucleus and experience a strong effective nuclear charge.
4. **Chlorine (Cl)**:
- Chlorine is in the halogen group (Group 17) as well.
- It has a slightly higher ionization energy than fluorine but lower than nonmetals in the previous periods. Chlorine has one more electron in its 3p subshell compared to fluorine, and this additional electron increases the shielding effect, reducing the effective nuclear charge felt by the outermost electrons.
In general, ionization energy increases across a period from left to right on the periodic table due to the increasing effective nuclear charge. Elements on the left side have lower ionization energy because their outermost electrons are farther from the nucleus and are shielded by inner electrons, making them easier to remove. Elements on the right side have higher ionization energy because their outermost electrons are closer to the nucleus and experience a stronger attraction, making them more difficult to remove.