---
title: "Platinum (Pt) — element 78"
description: "Platinum is element 78, symbol Pt, atomic weight 195.08. Configuration, properties, uses and neighbours."
url: https://atoneplace.net/element/platinum/
site: "At One Place"
---

# Platinum (Pt)

**Platinum — element 78: Pt**

195.08 u · Transition metal · period 6, group 10

Cisplatin was found by accident in 1965: Barnett Rosenberg was studying whether electric fields affect bacterial growth, noticed the bacteria had stopped dividing, and traced it to platinum dissolving out of what he had assumed were inert electrodes. The drug and its successors cure the large majority of testicular cancers and are used against many others. Spanish colonists in Colombia named it platina, "little silver", and threw it away as an unwanted contaminant of gold ore — it melts at 1,768 °C and they had no way to work it.

## Properties

- **Atomic number:** 78
- **Symbol:** Pt
- **Standard atomic weight:** 195.08 u
- **Category:** Transition metal
- **Group:** 10
- **Period:** 6
- **Block:** d-block
- **Electron configuration:** [Xe] 6s¹ 4f¹⁴ 5d⁹
- **Electrons per shell:** 2, 8, 18, 32, 17, 1
- **Melting point:** 2,041.55 K — 1768.4 °C — 3215.1 °F
- **Boiling point:** 4,098 K — 3824.8 °C — 6916.7 °F
- **Density:** 21.46 g/cm³
- **Electronegativity:** 2.28 (Pauling)
- **Oxidation states:** +4, +2
- **Discovered:** 1735 by Antonio de Ulloa

## Electron configuration

- **Full:** 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹ 4f¹⁴ 5d⁹
- **Noble gas shorthand:** [Xe] 6s¹ 4f¹⁴ 5d⁹
- **Shells:** K: 2 · L: 8 · M: 18 · N: 32 · O: 17 · P: 1

## What it is used for

- Catalytic converters on diesel engines
- Cisplatin and carboplatin chemotherapy drugs
- Jewellery, particularly wedding rings
- Laboratory crucibles and thermocouples
- Fuel cell and hydrogen electrolyser catalysts

> Anomalous electron configuration: [Xe] 6s¹ 4f¹⁴ 5d⁹ rather than the predicted 6s² 5d⁸.

## Neighbours in the table

| Z | Element | Symbol | Mass |
| --- | --- | --- | --- |
| 76 | Osmium | Os | 190.23 |
| 77 | Iridium | Ir | 192.22 |
| 78 | Platinum ← | Pt | 195.08 |
| 79 | Gold | Au | 196.97 |
| 80 | Mercury | Hg | 200.59 |

## Group 10

Elements in the same group share their outer electron count, which is why they behave similarly in reactions. Platinum sits in group 10 with nickel, palladium, darmstadtium.

## Common questions

### What is the atomic number of platinum?

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

### What is the symbol for platinum?

Pt.

### What is the electron configuration of platinum?

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶ 5s² 4d¹⁰ 5p⁶ 6s¹ 4f¹⁴ 5d⁹, or [Xe] 6s¹ 4f¹⁴ 5d⁹ in noble-gas shorthand.

### What is the melting point of platinum?

2,041.55 K — 1768.4 °C — 3215.1 °F

## Related pages

- [Osmium (Os)](https://atoneplace.net/element/osmium/)
- [Iridium (Ir)](https://atoneplace.net/element/iridium/)
- [Gold (Au)](https://atoneplace.net/element/gold/)
- [Mercury (Hg)](https://atoneplace.net/element/mercury/)
- [Nickel (Ni)](https://atoneplace.net/element/nickel/)
- [Palladium (Pd)](https://atoneplace.net/element/palladium/)
- [Darmstadtium (Ds)](https://atoneplace.net/element/darmstadtium/)

## Sources

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