Sodium Electron Configuration
Explore the complete electron configuration of sodium (Na, Z=11): 1s² 2s² 2p⁶ 3s¹ — with orbital diagrams, shell breakdown, and valence electron explanation.
Na
Sodium — Element 11
Period 3 · Group 1 · Alkali Metal
Full Configuration
1s² 2s² 2p⁶ 3s¹
Noble gas: [Ne] 3s¹
View:
Orbital Box Notation
1s
2 electrons
↑
↓
2s
2 electrons
↑
↓
2p
6 electrons
↑
↓
↑
↓
↑
↓
3s
1 electron — valence
↑
_
Arrows show electron spin direction (↑ = spin-up, ↓ = spin-down). Highlighted box = valence orbital.
Shell (Bohr) Model — 2·8·1
2
Shell 1 (K)
8
Shell 2 (L)
1
Shell 3 (M) — valence
Subshell Breakdown
| Subshell | Orbital Type | Max Capacity | Electrons Held | Notation |
|---|---|---|---|---|
| 1s | s (spherical) | 2 | 2 | 1s² |
| 2s | s (spherical) | 2 | 2 | 2s² |
| 2p | p (dumbbell, 3 orbitals) | 6 | 6 | 2p⁶ |
| 3s | s (spherical) — valence | 2 | 1 | 3s¹ |
| Total | 11 | |||
11
Atomic Number
11
Total Electrons
1
Valence Electrons
3
Electron Shells
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Summary
Explore the complete electron configuration of sodium (Na, Z=11): 1s² 2s² 2p⁶ 3s¹ — with orbital diagrams, shell breakdown, and valence electron explanation.
How it works
- Sodium has 11 electrons that fill orbitals in order of increasing energy (Aufbau principle).
- The first two electrons fill the 1s orbital: 1s².
- The next two fill the 2s orbital: 2s².
- Six electrons fill the three 2p orbitals: 2p⁶.
- The final electron occupies the 3s orbital: 3s¹ — this is the valence electron.
- The shorthand notation using the nearest noble gas is [Ne] 3s¹.
Use cases
- Verify sodium's electron configuration for chemistry homework.
- Understand why sodium has a +1 oxidation state and reacts readily.
- Compare period-3 element configurations side by side.
- Teach or learn orbital filling rules (Aufbau, Pauli, Hund) with a concrete example.
- Prepare for AP Chemistry or general chemistry exams.
- Explain why sodium is in Group 1 of the periodic table.
Frequently Asked Questions
Last updated: 2026-06-18 ·
Reviewed by Nham Vu