**Correct Option: D. Fluorine (F)** ### Explanation of the Correct Answer Electronegativity is a measure of an atom's ability to attract and hold onto electrons when it is part of a compound. The Pauling scale is one of the most commonly used scales to quantify electronegativity, and it assigns values to elements based on their ability to attract electrons in a chemical bond. 1. **Understanding Electronegativity**: - Electronegativity increases across a period (from left to right on the periodic table) because the number of protons in the nucleus increases, which enhances the positive charge and the ability to attract electrons. - Electronegativity decreases down a group (from top to bottom) because the additional electron shells increase the distance between the nucleus and the valence electrons, reducing the nucleus's pull on the outer electrons. 2. **Position of Elements in the Periodic Table**: - **Sodium (Na)**: Located in Group 1 (alkali metals), sodium has a low electronegativity of about 0.93. It readily loses its outer electron to form positive ions, making it less electronegative. - **Chlorine (Cl)**: Found in Group 17 (halogens), chlorine has a higher electronegativity of about 3.16. It is very effective at attracting electrons, but it is not the highest. - **Oxygen (O)**: Located in Group 16, oxygen has an electronegativity of about 3.44. It is quite electronegative and is known for forming strong bonds with other elements. - **Fluorine (F)**: Positioned in Group 17, fluorine has the highest electronegativity value of 3.98 on the Pauling scale. This means it has the strongest ability to attract electrons compared to all other elements. 3. **Why Fluorine is the Highest**: - Fluorine is the most electronegative element because it is at the top of the halogens and has a small atomic radius, which allows its nucleus to exert a strong attractive force on the electrons of other atoms. The combination of its high nuclear charge and small size makes it exceptionally effective at attracting electrons. ### Explanation of Why Other Options are Incorrect - **A. Sodium (Na)**: Sodium is an alkali metal with a low electronegativity. It tends to lose its single valence electron rather than attract electrons, making it the least electronegative among the options provided. - **B. Chlorine (Cl)**: While chlorine is highly electronegative, it is not as electronegative as fluorine. Chlorine's electronegativity of 3.16 is lower than that of fluorine, which is why it cannot be the correct answer. - **C. Oxygen (O)**: Oxygen is indeed very electronegative (3.44), but it still falls short of fluorine's electronegativity. Although oxygen is essential for many chemical reactions, it does not have the highest electronegativity. ### Summary of Key Points - **Electronegativity** measures an atom's ability to attract electrons in a bond. - **Fluorine (F)** has the highest electronegativity on the Pauling scale (3.98). - **Sodium (Na)** has low electronegativity (0.93) and tends to lose electrons. - **Chlorine (Cl)** and **Oxygen (O)** are electronegative but not as much as fluorine. This understanding of electronegativity is crucial for predicting how different elements will interact in chemical reactions, especially in the formation of ionic and covalent bonds.