**Correct Option: C. Fluorine (F)** ### Explanation of Why Fluorine Has the Highest Electronegativity **Electronegativity Defined:** Electronegativity is a measure of an atom's ability to attract and hold onto electrons when it is part of a compound. The higher the electronegativity, the stronger the atom's pull on electrons. **Periodic Trends:** 1. **Across a Period:** Electronegativity increases from left to right across a period in the periodic table. This is because as you move across a period, the number of protons in the nucleus increases, which enhances the positive charge and the ability to attract electrons. 2. **Down a Group:** Electronegativity decreases as you move down a group. This is due to the increasing distance between the nucleus and the outermost electrons, as well as the shielding effect caused by inner electron shells. **Position of Fluorine:** - Fluorine is located in Group 17 (the halogens) and Period 2 of the periodic table. - It has an atomic number of 9, meaning it has 9 protons and 9 electrons. - Being in the second period, it has a relatively small atomic radius, which allows its nucleus to exert a strong attractive force on the valence electrons of other atoms. **Electronegativity Values:** - The Pauling scale is commonly used to quantify electronegativity. On this scale: - Sodium (Na) has an electronegativity of about 0.93. - Chlorine (Cl) has an electronegativity of about 3.16. - Oxygen (O) has an electronegativity of about 3.44. - Fluorine (F) has the highest electronegativity value of approximately 3.98. ### Why Other Options Are Incorrect or Weaker **A. Sodium (Na):** - Sodium is an alkali metal located in Group 1. Alkali metals have low electronegativities because they tend to lose their single valence electron easily to achieve a stable electron configuration. Therefore, sodium's electronegativity is the lowest among the options provided. **B. Chlorine (Cl):** - Chlorine is a halogen and has a relatively high electronegativity (3.16), but it is still lower than that of fluorine. While chlorine can attract electrons effectively, it does not do so as strongly as fluorine, which is the most electronegative element. **D. Oxygen (O):** - Oxygen has a high electronegativity (3.44) and is very effective at attracting electrons. However, it is still less electronegative than fluorine. The presence of fluorine in the same group as oxygen but higher up in the periodic table contributes to its greater electronegativity. ### Summary of Key Points - **Electronegativity** measures an atom's ability to attract electrons. - **Fluorine (F)** has the highest electronegativity (3.98) on the periodic table. - **Trends:** Electronegativity increases across a period and decreases down a group. - **Comparison:** Sodium (Na) < Chlorine (Cl) < Oxygen (O) < Fluorine (F) in terms of electronegativity. This understanding of electronegativity and periodic trends is crucial for predicting how different elements will interact in chemical reactions, especially in the formation of ionic and covalent bonds.