As you move left to right across the periodic table, electronegativity tends to:

As you move left to right across the periodic table, electronegativity tends to increase. This trend occurs due to the increasing positive charge of the nucleus as protons are added to the element. The added protons contribute to a stronger attractive force on the electrons, which makes it more effective for an atom to pull electrons from other atoms during bonding.

Additionally, the increasing number of electrons in the same principal energy level does not significantly shield the increased nuclear charge, thus enhancing the nucleus's ability to attract bonding electrons. For example, when comparing elements like sodium and chlorine, chlorine has a much higher electronegativity because it has a stronger ability to attract shared electrons in a bond.

Overall, this left-to-right trend is a fundamental concept in understanding how different elements interact chemically, particularly in terms of their tendencies to form bonds with varying degrees of strength and polarity.