Valence Electrons in Thallium (Tl)

Valence Electrons in Thallium

Determine the number of valence electrons in Thallium (Tl, Element 81)

Step 1: Look up the electronic configuration for Thallium

The abbreviated (condensed) ground electronic configuration for Thallium is:

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p¹

Calculate Electronic Configuration for Thallium

Step 2: Identify the outermost electrons using the electronic configuration

Electrons in atomic orbitals outside the [Xe] core are the outermost electrons:

4f¹⁴ 5d¹⁰ 6s² 6p¹

Step 3: Use the principle quantum number to identify the valence electrons

Extract the principle quantum number, n, and number of electrons from the electron configuration:

The outermost electrons with the largest principal quantum number (in this case, n = 6) are valence electrons.

Answer

Thallium (Tl) has 3 (2 + 1) valence electrons.