Anand Classes brings you a detailed explanation of Factors Affecting Electronegativity in Chemistry, an important concept for JEE, NEET, and CBSE Class 11 exams. Electronegativity is not a fixed property of an atom; rather, it varies with factors such as oxidation state, type of hybridisation, and the nature of substituents. Understanding these variations helps students build strong conceptual clarity and perform better in competitive exams. Click the print button to download study material and notes.
What are the Factors Affecting Electronegativity ? Explain
Electronegativity of an atom is not a fixed quantity; it depends on several factors. The major factors are:
Oxidation State
- In general, electronegativity increases with an increase in the positive oxidation state of an atom.
- This happens because a higher positive oxidation state reduces the size of the atom, increasing its tendency to attract electrons.
Example:
- Pauling electronegativity of Fe(II) = 1.83
- Pauling electronegativity of Fe(III) = 1.96
Other examples:
| Ion | Electronegativity | Ion | Electronegativity |
|---|---|---|---|
| Tl(I) | 1.62 | Tl(III) | 2.04 |
| Sn(II) | 1.80 | Sn(IV) | 1.96 |
| Fe(II) | 1.83 | Fe(III) | 1.96 |
| Cu(I) | 1.90 | Cu(II) | 2.00 |
- For anions: Electronegativity decreases with increasing negative charge.
This is because a more negatively charged ion already has excess electrons and hence attracts additional electrons less strongly.
Type of Hybridisation
- The type of hybridisation of an atom also affects its electronegativity.
- Since s-orbitals are closer to the nucleus (greater penetration power) than p, d, or f orbitals, orbitals with higher s-character have greater electronegativity.
For Carbon:
| Hydrocarbon | Hybridisation | s-character | Electronegativity |
|---|---|---|---|
| Methane (CHโ) | spยณ | 25% | 2.48 |
| Ethylene (CโHโ) | spยฒ | 33% | 2.75 |
| Acetylene (CโHโ) | sp | 50% | 3.29 |
Thus, electronegativity increases in the order: CHโ < CโHโ < CโHโ
For Nitrogen:
- Electronegativity values are:
- spยณ = 3.68
- spยฒ = 3.94
- sp = 4.67
Nature of Substituents
- The electronegativity of a group varies depending on the nature of the substituents attached, due to the inductive effect.
Examples:
| Group | Electronegativity |
|---|---|
| โCHโ | 2.30 |
| โCClโ | 3.30 |
| โCFโ | 3.35 |
Here, the electronegativity of the carbon atom is modified by the attached substituents (H, Cl, or F).
FAQs on Factors Affecting Electronegativity Class 11 CBSE Boards
Q1. Is electronegativity a fixed property of an element?
No. Electronegativity is not fixed; it depends on factors like oxidation state, type of hybridisation, and the nature of substituents attached to the atom.
Q2. Why does electronegativity increase with the positive oxidation state of an atom?
Because a higher positive charge reduces the atomic size and increases the nucleusโs pull on electrons, thereby increasing the atomโs tendency to attract electrons.
Q3. Why does electronegativity decrease with increasing negative charge on an anion?
A negatively charged ion already has excess electrons, so its ability to attract additional electrons decreases as the negative charge increases.
Q4. How does hybridisation affect electronegativity?
Hybrid orbitals with more s-character are closer to the nucleus, hence attract electrons more strongly.
Electronegativity increases in the order:
spยณ < spยฒ < sp
Q5. What is the electronegativity trend of carbon in CHโ, CโHโ, and CโHโ?
Answer
- CHโ (spยณ) โ 2.48
- CโHโ (spยฒ) โ 2.75
- CโHโ (sp) โ 3.29
Thus, CโHโ > CโHโ > CHโ.
Q6. How does the inductive effect of substituents affect electronegativity?
Electronegativity of a group depends on the attached substituents:
- โCHโ (2.30) < โCClโ (3.30) < โCFโ (3.35)
Electronegative substituents like Cl and F pull electron density away, thereby increasing the effective electronegativity of carbon.
Q7. Which nitrogen hybrid orbital has the highest electronegativity?
Nitrogen in sp hybridisation (4.67) has the highest electronegativity compared to spยฒ (3.94) and spยณ (3.68).
๐ Buy Study Material & Join Our Coaching
For premium study materials specially designed for JEE, NEET, NDA, and CBSE/ICSE Classes, visit our official study material portal:
๐ https://publishers.anandclasses.co.in/
To enroll in our offline or online coaching programs, visit our coaching center website:
๐ https://anandclasses.co.in/
๐ Call us directly at: +91-94631-38669
๐ฌ WhatsApp Us Instantly
Need quick assistance or want to inquire about classes and materials?
๐ฒ Click below to chat instantly on WhatsApp:
๐ Chat on WhatsApp
๐ฅ Watch Video Lectures
Get access to high-quality video lessons, concept explainers, and revision tips by subscribing to our official YouTube channel:
๐ Neeraj Anand Classes โ YouTube Channel
