Which of the following elements has the lowest electronegativity?

• A. Chlorine (Cl)
• B. Fluorine (F)
• C. Oxygen (O)
• D. Cesium (Cs)

Answer: (D)

Verified step by step guidance

1. Understand the concept of electronegativity: it is a measure of an atom's ability to attract and hold onto electrons in a chemical bond.
2. Recall the general trend of electronegativity in the periodic table: it increases across a period (left to right) and decreases down a group (top to bottom).
3. Identify the positions of the given elements on the periodic table: Fluorine (F), Oxygen (O), and Chlorine (Cl) are nonmetals located towards the right side and upper part of the table, while Cesium (Cs) is an alkali metal located in Group 1 at the bottom of the periodic table.
4. Apply the trend: since electronegativity decreases down a group and increases across a period, Cesium (Cs), being farthest to the left and lowest in the periodic table among the options, will have the lowest electronegativity.
5. Conclude that Cesium (Cs) has the lowest electronegativity compared to Chlorine (Cl), Fluorine (F), and Oxygen (O) based on its position in the periodic table.