Chapter 12: Problem 3

Give reasons for the following: (a) Boron forms covalent compounds. (b) \(\mathrm{AlCl}_{3}\) exists as a dimer but \(\mathrm{BCl}_{3}\) exists as a monomer. (c) \(\mathrm{BF}_{3}\) is a weaker Lewis acid than \(\mathrm{BCl}_{3}\).

Short Answer

Expert verified

Boron forms covalent bonds due to electron deficiency. AlCl3 forms a dimer due to the presence of unpaired electrons in aluminium, while no such electrons exist in boron in BCl3. The higher electronegativity of fluorine than chlorine pulls boron's electrons closer in BF3, reducing its ability to accept electron pairs, making it a weaker Lewis acid than BCl3.

Step by step solution

Reasoning for Boron forming Covalent Compounds

Boron, with a configuration of 2,3 in its 2nd shell, lacks the electrons to fulfill the octet rule to obtain a stability similar to the noble gases. Instead, boron forms covalent bonds, wherein it shares its three valance electrons with other elements to achieve a full octet configuration.

Reason for different structural properties of AlCl3 and BCl3

Aluminium in AlCl3 has one electron in the 3p orbital and three in the 3s orbital. This causes it to promote one of its 3s electrons to the vacant 3p orbital, causing the formation of dimer Al2Cl6. This doesn't occur with BCl3 because boron in BCl3 doesn't have any electron in the 2p orbital thus no dimer formation.

Explaination for difference in Lewis Acid strength

Lewis acid strength is determined by the degree to which it can accept electron pairs. In BF3, more electronegative fluorine atoms pull boron's electrons closer as compared to chlorine in BCl3, thus making it harder for boron to accept an electron pair. This makes BF3 a weaker Lewis acid than BCl3.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

Recommended explanations on Chemistry Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Give reasons for the following: (a) Boron forms covalent compounds. (b) \(\mathrm{AlCl}_{3}\) exists as a dimer but \(\mathrm{BCl}_{3}\) exists as a monomer. (c) \(\mathrm{BF}_{3}\) is a weaker Lewis acid than \(\mathrm{BCl}_{3}\).

Short Answer

Step by step solution

Reasoning for Boron forming Covalent Compounds

Reason for different structural properties of AlCl3 and BCl3

Explaination for difference in Lewis Acid strength

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Chemistry Textbooks

Chemical Reactions

Inorganic Chemistry

Kinetics

Chemistry Branches

Chemical Analysis

Organic Chemistry

Study anywhere. Anytime. Across all devices.