Which of the following correctly outlines why electronegativity increases across a period?The level of electron shielding increases There are more electrons and more repulsion between electronsThe atomic radius decreasesThere is an increase in nuclear charge and a decrease in the atomic radiusReport feedback

To determine why electronegativity increases across a period, we need to consider the given options and analyze each one step by step.

1. The level of electron shielding increases: Electron shielding refers to the ability of inner electrons to shield the outer electrons from the positive charge of the nucleus. However, as we move across a period, the number of inner electrons remains constant. Therefore, the level of electron shielding does not increase across a period.

2. There are more electrons and more repulsion between electrons: As we move across a period, the number of electrons does increase. However, this does not directly contribute to the increase in electronegativity. The repulsion between electrons is a factor that affects atomic size, not electronegativity.

3. The atomic radius decreases: This statement is correct. As we move across a period, the atomic radius generally decreases. This decrease in atomic radius is due to the increasing nuclear charge, which attracts the electrons more strongly, pulling them closer to the nucleus.

4. There is an increase in nuclear charge and a decrease in the atomic radius: This statement is also correct. As we move across a period, the nuclear charge increases because the number of protons in the nucleus increases. This increase in nuclear charge leads to a stronger attraction between the nucleus and the electrons, causing the atomic radius to decrease.

Based on the analysis, the correct answer is: "There is an increase in nuclear charge and a decrease in the atomic radius." This is the main reason why electronegativity increases across a period.