Summary
Electronegativity is a measure of an atom's ability to attract electrons within a molecule, influencing the type of bond formed between atoms. Factors such as nuclear charge, atomic radius, and electron shielding affect electronegativity, which generally increases across a period and decreases down a group in the Periodic Table.
- Electronegativity — the ability of an atom to attract electrons towards itself within a molecule. Example: Oxygen has a high electronegativity, attracting electrons strongly.
- Nuclear Charge — the positive charge of the nucleus that affects electron attraction. Example: Fluorine has a high nuclear charge, leading to high electronegativity.
- Atomic Radius — the size of an atom, affecting its ability to attract electrons. Example: Larger atoms like cesium have lower electronegativity.
- Shielding Effect — the reduction in effective nuclear charge on the electron cloud, due to inner-shell electrons. Example: Sodium has a significant shielding effect, reducing its electronegativity.
- Pauling Electronegativity — a scale used to predict bond types based on electronegativity differences. Example: A large difference in electronegativity between sodium and chlorine leads to ionic bonding.
Exam Tips
Key Definitions to Remember
- Electronegativity: The ability of an atom to attract electrons within a molecule.
- Nuclear Charge: The total positive charge of the nucleus.
- Atomic Radius: The size of an atom from its nucleus to the outermost electron.
- Shielding Effect: The reduction in effective nuclear charge due to inner-shell electrons.
Common Confusions
- Confusing electronegativity with electron affinity.
- Misunderstanding the relationship between atomic radius and electronegativity.
Typical Exam Questions
- What is electronegativity? Electronegativity is the ability of an atom to attract electrons towards itself within a molecule.
- How does atomic radius affect electronegativity? A larger atomic radius generally results in lower electronegativity.
- Why does electronegativity increase across a period? It increases due to an increase in nuclear charge with a constant shielding effect.
What Examiners Usually Test
- Understanding of factors affecting electronegativity.
- Ability to predict bond types based on electronegativity differences.
- Knowledge of periodic trends in electronegativity.