---
title: "Aluminum (Al) — element 13"
description: "Aluminum is element 13, symbol Al, atomic weight 26.982. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/aluminum/
site: "At One Place"
---

# Aluminum (Al)

**Aluminum — element 13: Al**

26.982 u · Post-transition metal · period 3, group 13

Aluminium is the most abundant metal in the Earth's crust and was, until the 1880s, more expensive than gold — Napoleon III is said to have reserved aluminium cutlery for his most honoured guests. The Hall-Héroult electrolysis process, invented independently by two 22-year-olds in 1886, collapsed the price by a factor of two hundred within a decade. It resists corrosion not by being unreactive but by being extremely reactive: a fresh surface oxidises within milliseconds into a dense film a few nanometres thick that seals the metal underneath.

## Properties

- **Atomic number:** 13
- **Symbol:** Al
- **Standard atomic weight:** 26.982 u
- **Category:** Post-transition metal
- **Group:** 13
- **Period:** 3
- **Block:** p-block
- **Electron configuration:** [Ne] 3s² 3p¹
- **Electrons per shell:** 2, 8, 3
- **Melting point:** 933.44 K — 660.3 °C — 1220.5 °F
- **Boiling point:** 2,792 K — 2518.8 °C — 4565.9 °F
- **Density:** 2.7 g/cm³
- **Electronegativity:** 1.61 (Pauling)
- **Oxidation states:** +3
- **Discovered:** 1825 by Hans Christian Ørsted

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p¹
- **Noble gas shorthand:** [Ne] 3s² 3p¹
- **Shells:** K: 2 · L: 8 · M: 3

## What it is used for

- Drink cans, foil and food packaging
- Window frames, ladders and curtain walling
- Aircraft skins and airframes
- Overhead power transmission lines, usually over a steel core
- Engine blocks, wheels and heat sinks

> Spelled "aluminum" here because US search volume dominates; "aluminium" is the IUPAC spelling and is carried as an alias. Recycling it takes about 5% of the energy of smelting it from ore, which is why used cans have real scrap value.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 11 | Sodium | Na | 22.99 |
| 12 | Magnesium | Mg | 24.305 |
| 13 | Aluminum ← | Al | 26.982 |
| 14 | Silicon | Si | 28.085 |
| 15 | Phosphorus | P | 30.974 |

## Group 13

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Aluminum sits in group 13 with boron, gallium, indium, thallium, nihonium.

## Common questions

### What is the atomic number of aluminum?

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

### What is the symbol for aluminum?

Al.

### What is the electron configuration of aluminum?

1s² 2s² 2p⁶ 3s² 3p¹, or [Ne] 3s² 3p¹ in noble-gas shorthand.

### What is the melting point of aluminum?

933.44 K — 660.3 °C — 1220.5 °F

## Related pages

- [Sodium (Na)](https://atoneplace.net/element/sodium/)
- [Magnesium (Mg)](https://atoneplace.net/element/magnesium/)
- [Silicon (Si)](https://atoneplace.net/element/silicon/)
- [Phosphorus (P)](https://atoneplace.net/element/phosphorus/)
- [Boron (B)](https://atoneplace.net/element/boron/)
- [Gallium (Ga)](https://atoneplace.net/element/gallium/)
- [Indium (In)](https://atoneplace.net/element/indium/)
- [Thallium (Tl)](https://atoneplace.net/element/thallium/)
- [Nihonium (Nh)](https://atoneplace.net/element/nihonium/)

## Sources

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