SCH 3201 LECTURE 6 GROUP 13

Group 13 elements: B (Boron), Al (Aluminum), Ga (Gallium), In (Indium), Tl (Thallium).
Distinction: Two s electrons and one p electron in outer shell.
Boron: Non-metal; others: Metals.
Main oxidation state: +3 (removal of 3 valence electrons).
Trends:
- Ionic radius is smaller for elements down the group.
- Ionization energies and electronegativities are higher than expected.

Element Electron Configuration Covalent Radius (Å) Ionic Radius M3+ (Å) MP (°C) Electronegativity
B	[He] 2s² 2p¹	0.82	0.20	2200	2.05
Al	[Ne] 3s² 3p¹	1.18	0.52	660	1.61
Ga	[Ar] 4s² 3d¹⁰ 4p¹	1.26	0.60	29	1.76
In	[Kr] 5s² 4d¹⁰ 5p¹	1.44	0.81	157	1.66
Tl	[Xe] 6s² 4f¹⁴ 5d¹⁰ 6p¹	1.48	0.95	304	1.79

Oxidation States:
- Boron: Only +3
- Aluminum: +3 is stable; +1 is unstable.
- For Ga to Tl, +1 becomes stable due to inert pair effect.
Hydrides:
- Boron forms boranes (e.g., diborane B2H6).
- Aluminum and Gallium form similar compounds.
Oxides and Hydroxides:
- M₂O₃ formation (sesquioxides).
- Boron oxide is acidic, leading to various reactions with acids and metal oxides.
- Aluminum oxide (Al₂O₃) is amphoteric and has a strong affinity for oxygen.
- Gallium forms amphoteric oxides and hydroxides.

Group III metal salts are often soluble due to small cation size and high charge (M³⁺).
Example: AlCl₃ solubility due to high hydration energy
- ΔH_hydration for Al³⁺: -4665 J/mol.

Form complexes more readily due to small size and high charge.
Occurrence in nature:
- Boron: Found as sodium borate (borax).
- Aluminum: Most abundant metallic element.
- Gallium: Smaller quantitiesassociated

Boron: Reduced from B₂O₃ with Na or Mg.
Aluminum: Extracted from bauxite via NaOH and electrolysis.
Gallium, Indium, Thallium: Typically obtained through electrolysis of aqueous salt solutions.

very brief