Electron Configuration Practice Test 2026 – Complete Exam Prep

The electron configuration provided, [Kr] 5s² 4d⁶, indicates that the element is found after krypton in the periodic table. The notation [Kr] signifies that the element has the same electron configuration as krypton, which accounts for the first 36 electrons. The additional 8 electrons, represented by 5s² 4d⁶, complete the configuration for this element.

In the configuration, the 5s subshell contains 2 electrons, and the 4d subshell contains 6 electrons. The presence of 6 electrons in the 4d subshell suggests that the element is in the transition metals group, specifically in the fourth period of the periodic table. The 4d block starts with Yttrium (Y) and goes through to Cadmium (Cd), covering a series of elements that fill the 4d subshell.

Counting from the start of the transition metals in period 4, we find:

- Yttrium (Y, [Kr] 5s² 4d¹)

- Zirconium (Zr, [Kr] 5s² 4d²)

- Niobium (Nb, [Kr] 5