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.
The sodium electron configuration is 1s² 2s² 2p⁶ 3s¹, or [Ne] 3s¹ in noble-gas shorthand.
Use the Sodium Electron Configuration
Sodium — Element 11
Period 3 · Group 1 · Alkali Metal
Full Configuration
1s² 2s² 2p⁶ 3s¹
Noble gas: [Ne] 3s¹
Orbital Box Notation
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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Quick answer
The sodium electron configuration is 1s² 2s² 2p⁶ 3s¹, or [Ne] 3s¹ in noble-gas shorthand. Sodium (Na, Z = 11) arranges its 11 electrons 2-8-1 by shell, with a single valence electron in the 3s orbital.
Examples
| Shell | Subshells | Electrons |
|---|---|---|
| n = 1 | 1s² | 2 |
| n = 2 | 2s² 2p⁶ | 8 |
| n = 3 | 3s¹ | 1 (valence) |
| Total | [Ne] 3s¹ | 11 |
Switch to the orbital or shell diagram, or copy any notation in one click.
Summary
Sodium (Na) has atomic number 11 and electron configuration 1s² 2s² 2p⁶ 3s¹, often written in shell notation as 2-8-1. Its single valence electron in the 3s orbital makes sodium highly reactive and explains its +1 oxidation state. This tool provides an interactive breakdown of each orbital, an energy level diagram, and answers to common questions about sodium's electronic structure.
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.