Who discovered Radium and when?

Radium was discovered on December 26, 1898, by Marie Sklodowska-Curie and Pierre Curie. They isolated it from pitchblende (uraninite) ore while investigating why the ore was more radioactive than uranium alone could explain. Marie Curie later won a second Nobel Prize (Chemistry, 1911) specifically for her discovery of radium and polonium.

Why is Radium so radioactive?

Radium is radioactive because its nucleus is too large to be stable. Ra-226, the most common isotope, undergoes alpha decay with a half-life of 1600 years, releasing a helium-4 nucleus and transforming into radon-222. All 33 known radium isotopes are unstable because no combination of 88 protons produces a stable nucleus.

What is the most stable isotope of Radium?

Ra-226 is the most stable isotope of radium, with a half-life of approximately 1600 years. It decays via alpha emission to radon-222, and is itself produced in the decay chain of uranium-238. Ra-228 (half-life ~5.75 years) is the second most stable isotope.

What were Radium's historical medical uses?

From the early 1900s through the mid-20th century, radium was used in cancer treatment via brachytherapy, where radium-filled needles or tubes were implanted in or near tumors. Its gamma and alpha radiation damaged cancer cells. Radium was also notoriously used in luminous paint for watch dials and instrument panels — a practice that caused fatal radiation poisoning among "Radium Girls" factory workers.

Is Radium still used today?

Modern medical and industrial applications of radium have been almost entirely replaced by safer, purpose-designed radionuclides. Ra-223 (sold as Xofigo) is an FDA-approved radiopharmaceutical for treating bone metastases from prostate cancer, representing the only significant current medical use. Radium also appears naturally in groundwater and building materials derived from uranium-bearing rock.

Where does Radium occur naturally?

Radium occurs in trace amounts wherever uranium or thorium ores are found, because it is a decay product in their radioactive series. The primary mineral source is uraninite (pitchblende), but carnotite, autunite, and other uranium-bearing minerals also contain radium. The Earth's crust contains roughly 1 gram of Ra-226 per 3 million metric tons of rock on average.

Radium Element Properties

Look up every key property of Radium (Ra, Z=88) — from atomic mass and electron configuration to melting point, radioactivity, and historical significance.

Ra 88

Radium (Ra)

Atomic number 88 · Group 2 · Period 7 · Alkaline Earth Metal

A highly radioactive silvery-white metal discovered by Marie and Pierre Curie in 1898 — historically significant in cancer treatment and the study of radioactivity.

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Identity & Classification

Atomic Structure

Physical Properties

Thermodynamic Properties

Chemical Properties

Notable Isotopes

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Summary

Radium (symbol Ra, atomic number 88) is a highly radioactive alkaline earth metal in Group 2 of the periodic table, Period 7. Discovered in 1898 by Marie and Pierre Curie, radium was the first element isolated in pure metallic form from a radioactive ore. It is silvery-white but rapidly blackens in air due to nitride formation. All isotopes of radium are radioactive; Ra-226, with a half-life of 1600 years, is the most stable and most abundant in nature. This reference card consolidates its atomic, physical, chemical, nuclear, and thermodynamic properties in a single searchable view.

How it works

The page loads a complete, curated dataset of Radium properties.
Properties are grouped into thematic sections: identity, atomic structure, physical, thermodynamic, chemical, and isotopes.
Use the search box to filter any property by name or value.
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Notable isotopes are listed with half-life and decay mode data.

Use cases

Quick reference during chemistry or nuclear physics coursework.
Verify data for lab reports or research papers on radioactive elements.
Study periodic trends across Group 2 alkaline earth metals.
Understand the historical role of radium in the discovery of radioactivity.
Medical physics research referencing historical radium brachytherapy.
Teaching periodic table concepts and nuclear decay chains.
Radiological safety assessments involving natural decay series.
Exploring the uranium-238 and thorium-232 decay chains that produce radium.

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Last updated: 2026-09-30 · Reviewed by Nham Vu