---
title: "Sodium (Na) — element 11"
description: "Sodium is element 11, symbol Na, atomic weight 22.99. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/sodium/
site: "At One Place"
---

# Sodium (Na)

**Sodium — element 11: Na**

22.99 u · Alkali metal · period 3, group 1

Sodium melts at 98 °C, so a lump of it turns liquid in hot water before it has finished reacting, which is exactly why the demonstration is so lively. Every nerve impulse in your body is a wave of sodium ions crossing a cell membrane, and the pump that moves them back out uses a substantial fraction of your resting energy budget. The metal was named by Davy from "soda", but its symbol comes from the Latin natrium, which is why sodium-potassium is written Na-K.

## Properties

- **Atomic number:** 11
- **Symbol:** Na
- **Standard atomic weight:** 22.99 u
- **Category:** Alkali metal
- **Group:** 1
- **Period:** 3
- **Block:** s-block
- **Electron configuration:** [Ne] 3s¹
- **Electrons per shell:** 2, 8, 1
- **Melting point:** 370.95 K — 97.8 °C — 208.0 °F
- **Boiling point:** 1,156 K — 882.9 °C — 1621.1 °F
- **Density:** 0.97 g/cm³
- **Electronegativity:** 0.93 (Pauling)
- **Oxidation states:** +1
- **Discovered:** 1807 by Humphry Davy

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s¹
- **Noble gas shorthand:** [Ne] 3s¹
- **Shells:** K: 2 · L: 8 · M: 1

## What it is used for

- Table salt and food preservation, as sodium chloride
- Sodium hydroxide for soap, paper and drain cleaner
- Sodium vapour street lamps, the orange ones
- Liquid-sodium coolant in fast breeder reactors
- Sodium bicarbonate in baking and in fire extinguishers

## Hazards

- Reacts vigorously with water, releasing hydrogen that often ignites
- Must be stored under oil or in an inert atmosphere
- Sodium hydroxide is severely caustic to skin and eyes

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 9 | Fluorine | F | 18.998 |
| 10 | Neon | Ne | 20.18 |
| 11 | Sodium ← | Na | 22.99 |
| 12 | Magnesium | Mg | 24.305 |
| 13 | Aluminum | Al | 26.982 |

## Group 1

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Sodium sits in group 1 with hydrogen, lithium, potassium, rubidium, cesium, francium.

## Common questions

### What is the atomic number of sodium?

11. That is the number of protons in its nucleus, which is what defines the element.

### What is the symbol for sodium?

Na.

### What is the electron configuration of sodium?

1s² 2s² 2p⁶ 3s¹, or [Ne] 3s¹ in noble-gas shorthand.

### What is the melting point of sodium?

370.95 K — 97.8 °C — 208.0 °F

## Related pages

- [Fluorine (F)](https://atoneplace.net/element/fluorine/)
- [Neon (Ne)](https://atoneplace.net/element/neon/)
- [Magnesium (Mg)](https://atoneplace.net/element/magnesium/)
- [Aluminum (Al)](https://atoneplace.net/element/aluminum/)
- [Hydrogen (H)](https://atoneplace.net/element/hydrogen/)
- [Lithium (Li)](https://atoneplace.net/element/lithium/)
- [Potassium (K)](https://atoneplace.net/element/potassium/)
- [Rubidium (Rb)](https://atoneplace.net/element/rubidium/)
- [Cesium (Cs)](https://atoneplace.net/element/cesium/)
- [Francium (Fr)](https://atoneplace.net/element/francium/)

## Sources

- Official vendor product documentation — At One Place (/about/)