Important Trends And Anomalous Properties Of Boron
Chapter Name : The P- Block Elements |
Sub Topic Code : 102_11_11_03_01 |
Topic Name : Important Trends And Anomalous Properties Of Boron |
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Sub Topic Name : Important Trends And Anomalous Properties Of Boron |
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Introduction
• The tri-chlorides, bromides and iodides of all group 13 elements being covalent in nature are hydrolysed in water. • Species like tetrahedral [M(OH)4]– and octahedral [M(H2O)6]3+, except in boron, exist in aqueous medium. • The monomeric trihalides, being electron deficient, are strong Lewis acids. • Boron trifluoride easily reacts with Lewis bases such as NH3 to complete octet around boron. • It is due to the absence of d orbitals that the maximum covalence of Boron is 4. • Since the d orbitals are available with Al and other elements, the maximum covalence can be expected beyond 4. • Most of the other metal halides (e.g., AlCl3) are dimerised through halogen bridging (e.g., Al2Cl6). • The metal species completes its octet by accepting electrons from halogen in these halogen bridged molecules.
Pre-Requisites:
Elements, periodic table, Group,
Activity:
• Group 13 has aluminium, boron which are important industrial elements.
Real Life Question:
What is boron used for?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| P block elements | Have the last electron in the outermost p orbital. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Borax powder | Important compound of boron used for cleaning. |
Real life uses :
• An important compound of boron is borax used for cleaning.
Places to visit :
Chemistry lab, kitchen.
Practical examples around us
| Examples | Explainations |
|---|---|
| Borax powder | Used for cleaning. |
What you learn in Theory:
• The tri-chlorides, bromides and iodides of all group 13 elements being covalent in nature are hydrolysed in water. • Species like tetrahedral [M(OH)4]– and octahedral [M(H2O)6]3+, except in boron, exist in aqueous medium. • The monomeric trihalides, being electron deficient, are strong Lewis acids. • Boron trifluoride easily reacts with Lewis bases such as NH3 to complete octet around boron. • It is due to the absence of d orbitals that the maximum covalence of Boron is 4. • Since the d orbitals are available with Al and other elements, the maximum covalence can be expected beyond 4. • Most of the other metal halides (e.g., AlCl3) are dimerised through halogen bridging (e.g., Al2Cl6). • The metal species completes its octet by accepting electrons from halogen in these halogen bridged molecules.
What you learn in Practice:
• Group 13 has aluminium, boron which are important industrial elements.