---
title: "Bismuth (Bi) — element 83"
description: "Bismuth is element 83, symbol Bi, atomic weight 208.98. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/bismuth/
site: "At One Place"
---

# Bismuth (Bi)

**Bismuth — element 83: Bi**

208.98 u · Post-transition metal · period 6, group 15

Bismuth was assumed to be the heaviest stable element until 2003, when a French team measured its alpha decay: bismuth-209 has a half-life of about 2 × 10¹⁹ years, roughly a billion times the age of the universe, so it is radioactive in the same sense that a bank vault is technically openable. It expands as it freezes, like water and unlike almost every other metal, which is why it was used in type metal. Grown slowly from a melt it forms iridescent stair-stepped hopper crystals whose colours come from an oxide film, and it is the most strongly diamagnetic element — a bismuth block visibly repels a strong magnet.

## Properties

- **Atomic number:** 83
- **Symbol:** Bi
- **Standard atomic weight:** 208.98 u
- **Category:** Post-transition metal
- **Group:** 15
- **Period:** 6
- **Block:** p-block
- **Electron configuration:** [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p³
- **Electrons per shell:** 2, 8, 18, 32, 18, 5
- **Melting point:** 544.55 K — 271.4 °C — 520.5 °F
- **Boiling point:** 1,837 K — 1563.8 °C — 2846.9 °F
- **Density:** 9.807 g/cm³
- **Electronegativity:** 2.02 (Pauling)
- **Oxidation states:** +3, +5
- **Discovered:** 1753 by Claude François Geoffroy

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p³
- **Noble gas shorthand:** [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p³
- **Shells:** K: 2 · L: 8 · M: 18 · N: 32 · O: 18 · P: 5

## What it is used for

- Bismuth subsalicylate — the pink stuff for upset stomachs
- Lead-free solder, plumbing fittings and free-machining brass
- Low-melting alloys for fire sprinkler links and fusible plugs
- Bismuth oxychloride, the pearlescent pigment in cosmetics
- Radiation shielding aprons, as a lead substitute

> Practically stable but formally radioactive: the alpha decay of bismuth-209 was detected in 2003 with a half-life around 2 × 10¹⁹ years. IUPAC still publishes a standard atomic weight for it, unlike the genuinely radioactive elements that follow.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 81 | Thallium | Tl | 204.38 |
| 82 | Lead | Pb | 207.2 |
| 83 | Bismuth ← | Bi | 208.98 |
| 84 | Polonium | Po | [209] |
| 85 | Astatine | At | [210] |

## Group 15

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Bismuth sits in group 15 with nitrogen, phosphorus, arsenic, antimony, moscovium.

## Common questions

### What is the atomic number of bismuth?

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

### What is the symbol for bismuth?

Bi.

### What is the electron configuration of bismuth?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s² 4f¹⁴ 5d¹⁰ 6p³, or [Xe] 6s² 4f¹⁴ 5d¹⁰ 6p³ in noble-gas shorthand.

### What is the melting point of bismuth?

544.55 K — 271.4 °C — 520.5 °F

## Related pages

- [Thallium (Tl)](https://atoneplace.net/element/thallium/)
- [Lead (Pb)](https://atoneplace.net/element/lead/)
- [Polonium (Po)](https://atoneplace.net/element/polonium/)
- [Astatine (At)](https://atoneplace.net/element/astatine/)
- [Nitrogen (N)](https://atoneplace.net/element/nitrogen/)
- [Phosphorus (P)](https://atoneplace.net/element/phosphorus/)
- [Arsenic (As)](https://atoneplace.net/element/arsenic/)
- [Antimony (Sb)](https://atoneplace.net/element/antimony/)
- [Moscovium (Mc)](https://atoneplace.net/element/moscovium/)

## Sources

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