Lecture Notes: Electronegativity

Definition of Electronegativity

Electronegativity: The ability of an atom to attract electrons to itself.
Example: Fluorine is highly electronegative; it strongly attracts electrons to achieve a full outer electron shell and satisfy the octet rule.

Halogens (e.g., fluorine, chlorine, bromine) are highly electronegative and tend to gain electrons.
Metals (e.g., sodium) are usually electropositive, meaning they tend to lose electrons to form cations.
Non-metals: Tend to be electronegative.
Metals: Tend to be electropositive.

Across a Period: Electronegativity increases from left to right.
- Example values: Boron (2.0), Carbon (2.5), Nitrogen (3.0), Oxygen (3.5), Fluorine (4.0).
Down a Group: Electronegativity decreases as you move down.
Overall Trend: Electronegativity increases towards fluorine, which is the most electronegative element.
Noble Gases: Do not have electronegativity values as they are stable and do not tend to gain electrons.

Chromium vs. Arsenic
- Arsenic (non-metal) is more electronegative than Chromium (metal).
- Values: Chromium (1.6), Arsenic (2.0).
Calcium vs. Zinc
- Zinc is more electronegative than calcium.
- Values: Calcium (1.0), Zinc (1.6).
Selenium vs. Tellurium
- Selenium is more electronegative as it is above Tellurium in the periodic table.
- Values: Selenium (2.4), Tellurium (2.1).
Chlorine Cation vs. Chlorine Anion
- Chlorine cation is more electronegative because positively charged ions have a stronger desire for electrons.
Nickel 2+ vs. Nickel 3+ Cation
- Nickel 3+ cation is more electronegative due to higher positive charge.

Elements: Manganese, Oxygen, Copper, Phosphorus, Rubidium.
Electronegativity increases towards fluorine.
Order: Rubidium < Manganese < Copper < Phosphorus < Oxygen.
- Values: Rubidium (0.8), Manganese (1.5), Copper (1.9), Phosphorus (2.1), Oxygen (3.5).