What general trend is observed in electronegativity as you move down a group in the periodic table?

As you move down a group in the periodic table, electronegativity decreases due to several factors related to atomic structure. Electronegativity is the tendency of an atom to attract electrons in a chemical bond. When an element is located lower in a group, its atomic number increases, which leads to a greater number of electron shells surrounding the nucleus.

This increase in electron shells creates a greater distance between the nucleus and the valence electrons. The effect of the positive charge of the nucleus on the outer electrons becomes weaker because of this increased distance, a phenomenon known as shielding. The additional inner electron shells shield the valence electrons from the full effect of the nuclear charge, reducing the atom's ability to attract bonding electrons. Consequently, the electronegativity values decrease as you move down a group.

This trend is evident in common groups like the halogens, where fluorine at the top has a higher electronegativity than iodine at the bottom. Thus, the correct understanding aligns with the trend of decreasing electronegativity as you progress down a group in the periodic table.