---
title: "Scandium (Sc) — element 21"
description: "Scandium is element 21, symbol Sc, atomic weight 44.956. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/scandium/
site: "At One Place"
---

# Scandium (Sc)

**Scandium — element 21: Sc**

44.956 u · Transition metal · period 4, group 3

Mendeleev predicted scandium in 1871, called it eka-boron, and specified its atomic weight and oxide formula from the gap in his table; Nilson found it eight years later and the numbers matched. It is not actually rare — there is more scandium in the crust than lead — but it is almost never concentrated anywhere, so it is produced in tonnes per year rather than thousands of tonnes, mostly as a by-product of uranium and titanium refining. Adding a fraction of a percent to aluminium roughly doubles the strength of the weld zone, which is why it turns up in frames that have to be welded and still be light.

## Properties

- **Atomic number:** 21
- **Symbol:** Sc
- **Standard atomic weight:** 44.956 u
- **Category:** Transition metal
- **Group:** 3
- **Period:** 4
- **Block:** d-block
- **Electron configuration:** [Ar] 4s² 3d¹
- **Electrons per shell:** 2, 8, 9, 2
- **Melting point:** 1,814 K — 1540.8 °C — 2805.5 °F
- **Boiling point:** 3,109 K — 2835.8 °C — 5136.5 °F
- **Density:** 2.99 g/cm³
- **Electronegativity:** 1.36 (Pauling)
- **Oxidation states:** +3
- **Discovered:** 1879 by Lars Fredrik Nilson

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹
- **Noble gas shorthand:** [Ar] 4s² 3d¹
- **Shells:** K: 2 · L: 8 · M: 9 · N: 2

## What it is used for

- Scandium-aluminium alloy in high-end bicycle frames and baseball bats
- Airframe components on the Russian MiG-21 and MiG-29
- Scandium iodide in metal-halide lamps for stadium lighting
- Solid oxide fuel cell electrolytes

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 19 | Potassium | K | 39.098 |
| 20 | Calcium | Ca | 40.078 |
| 21 | Scandium ← | Sc | 44.956 |
| 22 | Titanium | Ti | 47.867 |
| 23 | Vanadium | V | 50.942 |

## Group 3

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Scandium sits in group 3 with yttrium.

## Common questions

### What is the atomic number of scandium?

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

### What is the symbol for scandium?

Sc.

### What is the electron configuration of scandium?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹, or [Ar] 4s² 3d¹ in noble-gas shorthand.

### What is the melting point of scandium?

1,814 K — 1540.8 °C — 2805.5 °F

## Related pages

- [Potassium (K)](https://atoneplace.net/element/potassium/)
- [Calcium (Ca)](https://atoneplace.net/element/calcium/)
- [Titanium (Ti)](https://atoneplace.net/element/titanium/)
- [Vanadium (V)](https://atoneplace.net/element/vanadium/)
- [Yttrium (Y)](https://atoneplace.net/element/yttrium/)

## Sources

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