Groups 13 and 14: Anomalies and Trends
Boron and carbon differ markedly from their heavier congeners because of small size, high electronegativity and absence of d orbitals.
What is Groups 13 and 14: Anomalies and Trends?
Boron and carbon differ markedly from their heavier congeners because of small size, high electronegativity and absence of d orbitals.
Key formula / rule: The inert pair effect stabilises the lower oxidation state down a group.
Key points
- Explain the anomalous behaviour of the first element in groups 13 and 14.
- Compare the stability of oxidation states down these groups.
Common exam trap
Expecting boron to form simple B3+ ions.
Definitions
- Term
Groups 13 and 14: Anomalies and Trends
- Meaning
Boron and carbon differ markedly from their heavier congeners because of small size, high electronegativity and absence of d orbitals.
- Term
Groups 13 and 14: Anomalies and Trends — explanation
- Meaning
The inert pair effect makes lower oxidation states more stable down the groups, explaining why thallium prefers +1 and lead prefers +2. Catenation is strongest for carbon.
Learning objectives
Explain the anomalous behaviour of the first element in groups 13 and 14.
Compare the stability of oxidation states down these groups.
Formulae
- Key point
The inert pair effect stabilises the lower oxidation state down a group.
- Key point
Boron is electron deficient and forms Lewis acidic compounds.
- Key point
Catenation ability decreases sharply from carbon to silicon.
Prerequisites
CHE-U2-PT-T1-S1-C2
Common mistakes
Expecting boron to form simple B3+ ions.
Assuming the highest oxidation state is always the most stable.
Keywords
Groups
Anomalies
Trends
Practice preview
What is the maximum covalency exhibited by boron?…
easy
Which element in Group 14 exhibits the strongest tendency for catenation?…
easy
Identify the correct order of acidic strength for the oxides of Group 13 elements.…
medium