What NEET Asks
- Direct questions on valence shell electronic configurations of B, Al, Ga, In, Tl.
- Understanding the role of d and f electrons in heavier elements.
- Predicting group/period based on given configurations.
Key Points
- Group 13 elements (Boron family) include Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), and Thallium (Tl).
- Their general valence shell electronic configuration is ns²np¹.
- Boron (Z=5): [He] 2s²2p¹
- Aluminium (Z=13): [Ne] 3s²3p¹
- Gallium (Z=31): [Ar] 3d¹⁰ 4s²4p¹ (Note the filled 3d orbitals, responsible for poor shielding)
- Indium (Z=49): [Kr] 4d¹⁰ 5s²5p¹ (Note the filled 4d orbitals)
- Thallium (Z=81): [Xe] 4f¹⁴ 5d¹⁰ 6s²6p¹ (Note the filled 4f and 5d orbitals; crucial for understanding the inert pair effect)
Must-Know Formula / Reaction
- General valence shell electronic configuration:
ns²np¹n: Principle quantum number of the outermost shell.s: s-orbital, holding 2 electrons.p: p-orbital, holding 1 electron.
Common Mistakes
- Students often forget to include the filled d and f orbitals for heavier elements like Ga, In, and Tl, especially when writing full configurations.
- Don't confuse the principal quantum number 'n' with the period number directly when d and f block elements are involved in the core.
- Incorrectly identifying the correct noble gas core for elements, particularly for Thallium.
Rapid Revision
Group 13 elements uniformly have a valence configuration ns²np¹. Remember to account for the presence of filled 3d¹⁰ (Ga), 4d¹⁰ (In), and 4f¹⁴ 5d¹⁰ (Tl) orbitals in their respective core configurations. These inner electrons are vital for explaining property trends.