Define electronegativity and then describe the trends in electronegativity within groups and across periods in the periodic table. Provide examples of the elements with the highest electronegativity value within a group and an example of an element with the highest energy level across a period.
https://en.wikipedia.org/wiki/Electronegativity
Electronegativity is a measure of an atom's ability to attract and hold electrons towards itself in a chemical bond. It helps determine the polarity of a bond, where a highly electronegative element tends to "hog" the shared electrons, while a less electronegative element will have a partial positive charge.
Trends in electronegativity can be observed both within groups (vertical columns) and across periods (horizontal rows) in the periodic table.
Within a group (such as Group 1, alkali metals), electronegativity generally decreases as you move down the group. This is because the outermost electrons are further away from the positively charged nucleus, leading to a weaker attraction towards these electrons. As a result, elements lower in the group have lower electronegativity values. For example, in Group 1, fluorine (F) has the highest electronegativity value of 3.98, while cesium (Cs) at the bottom has an electronegativity value of 0.79.
Across a period, electronegativity generally increases from left to right. This is due to two factors: increased effective nuclear charge (the net attractive force on valence electrons by the nucleus) and decreasing atomic radius. As you move from left to right across a period, the number of protons in the nucleus increases, which increases the effective nuclear charge. This stronger positive charge pulls the valence electrons closer to the nucleus, resulting in higher electronegativity. Additionally, the atomic radius decreases across a period, leading to a stronger attraction between the positively charged nucleus and the valence electrons. For example, in Period 3, the element with the highest electronegativity is chlorine (Cl) with a value of 3.16.
To find the electronegativity values for specific elements in a group or period, you can consult a periodic table or refer to various electronegativity charts available online or in chemistry textbooks.