Mendeleev · Science

Electron configuration: reading atomic architecture

Electron configuration describes how electrons occupy energy levels and subshells. It connects an element's position in the periodic table with a more detailed quantum description.

Understand before calculating

Electron configuration describes how electrons occupy energy levels and subshells. It connects an element's position in the periodic table with a more detailed quantum description.

Example

For sodium, 1s² 2s² 2p⁶ 3s¹ immediately shows a single electron occupying the outer 3s subshell.

The classic trap

Do not turn a model into a literal photograph of reality. Scientific models select particular properties to explain or predict a phenomenon; knowing their limits is part of using them correctly.

Understanding check

Explain the concept to someone who knows the periodic table but not this chapter. Then give one example and one situation where the most common shortcut would become misleading.

For sodium, 1s² 2s² 2p⁶ 3s¹ immediately shows a single electron occupying the outer 3s subshell.