Valence Electrons in Actinium (Ac)

Valence Electrons in Actinium

Determine the number of valence electrons in Actinium (Ac, Element 89)

Step 1: Look up the electronic configuration for Actinium

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

[Rn] 6d¹ 7s²

Calculate Electronic Configuration for Actinium

Step 2: Identify the outermost electrons using the electronic configuration

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

6d¹ 7s²

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 = 7) are valence electrons.

Answer

Actinium (Ac) has 2 valence electron(s).