A Complete Overview on Curium

When you go through the periodic table in chemistry, you come across various chemical elements of the known universe. This table is divided into several groups, periods, and blocks. The well-organised arrangement is based on the atomic numbers, chemical properties, and electron configuration of these chemical properties.

In the following post, you will learn about one of these elements – curium. This element was identified by an American chemist Glenn T. Seaborg and his colleagues in 1944. The atomic number of curium is 1996, and it is extremely useful in multiple scientific researches. Generally, the production of curium occurs by neutron bombardment of plutonium or uranium in nuclear reactors. 

Here are more details about curium. Let’s start learning!

Curium Element

Curium is a synthetic chemical element and one of the elements from actinoid series. It is known to be the 3rd transuranium element discovered yet. Curium is named after the famous French physicist and chemist Pierre Curie and Marie Curie who are regarded as the pioneer of radioactivity. Cm suggests as curium symbol in chemistry. 

Initially, curium was obtained by bombarding helium ions on one of the plutonium isotopes – Pt-239. It is a radioactive, chemically active, electro-positive substance that has specific magnetic properties. Its resistivity increases along with the inclining temperature. 

Scientists who also involved with Seaborg in the discovery of curium were – Albert Ghiorso, Ralph A. James. These are some vital curium element facts that you must know.

Properties of Curium

As a chemical substance, this metal has some unique properties. Below are some physical and chemical properties of curium.

Physical Properties of Curium

Chemical Symbol of Curium


Curium Atomic Number



Metallic silver. Due to its high radioactivity, it glows purple when in the dark.




Solid at standard temperature (20oC).


Crystal structure with double hexagonal close-packed.





Relative Atomic Weight 

247 gram per mole



Period and Block

7 – f

Electron Configuration of Curium 

[Rn] 5f7 6d1 7s2

Melting Point of Curium 

1340oC, 1613 K, 2444oF

Boiling Point of Curium

3110oC, 3383 K, 5630oF

Density of Curium 

13.51 gram per cm

Common Isotopes

Cm- 242, Cm-243, Cm-244, Cm-245, Cm-246, Cm-247, Cm-248, Cm-250

Main Isotopes

Cm-243, Cm-248

Chemical Properties of Curium

Coordination Number

Commonly its complexes show 9-fold coordination.


+3, +4, +5, +6


Highly toxic. Curium can be piled up in various human organs like lungs, bones, and liver. It can also cause cancer.


It oxidises easily and creates fluorescent complexes.


1.3 Pauling

Heat of Fusion

15 Kilojoule per mole 


The preparation of metallic curium occurs by reducing its components. Primarily, curium (III) fluoride was utilised to produce metallic curium. This specific reaction was initiated in a synthetic environment that is free from oxygen and water. The environment was created inside an apparatus that was composed of tungsten and tantalum. Moreover, lithium or barium was used as reducing agent.

CmF₃ + 3 Li 🡪 Cm + 3 LiF

Another way of obtaining metallic curium is by reduction of curium (IV) oxide. This reaction can be conducted by using zinc-magnesium alloy in a mixture of magnesium fluoride and magnesium chloride.

Compounds of Curium

  • Oxides

As said earlier, there are four oxidation states of curium available. However, +3 oxidation compounds are mostly found. This metal reacts readily with oxygen and produces (primarily) CmO₂ and Cm₂O₃  oxides. Nonetheless, another divalent oxide CmO can also be found by different reactions.

By burning curium oxalate or (Cm₂(C₂O4)₃ ) and curium nitrate or (Cm(NO₃)₃) in 100% puro oxygen, black coloured CmO2 is produced. 

(Cm₂(C₂O4)₃) 🡪 2CmO₂ + 4 CO₂ + 2 C

On further heating at 600 – 650oC in a vacuum, CmO₂ converts into whitish Cm2O₃.

 4 CmO₂ 🡪 2 Cm₂O₃ + O₂

Another method of obtaining Cm₂O₃ is by reduction of CmO₂ with the help of molecular hydrogen.

2 CmO₂ + H₂ 🡪 Cm₂O₃ + H₂O

Moreover, some ternary oxides such as M (II) CmO₃ are also found. Here, M suggests a divalent metal like barium. 

Also, by thermal oxidation of curium hydride, volatile CmO₂ and CmO₃ are produced as per reports. Curium trioxide or CmO₃ is an example of a +6 oxidation state compound.

  • Halides

By introducing fluoride ions to curium (III) solutions, colourless curium (III) fluoride or CmF3 can be formed. However, another halide – tetravalent curium (IV) fluoride can only be generated by the reaction between CmF₃ and molecular fluorine.

2 CmF₃ + F₂ 🡪 2 CmF₄

Multiple ternary fluorides can also be created with a generic form of A₇Cm₆F₃₁. Here, A suggests alkali metals.

Curium (III) hydroxide or Cm(OH)₃  reacts with anhydrous hydrogen chloride to produce colourless curium (III) chloride or CmCl₃. Curium (III) chloride can also be transformed into colourless curium (III) iodide and light green to colourless curium (III) bromide. These conversions occur when CmCl₃  reacts with ammonium salt at 400 – 450oC temperature. 

Other Compounds

At high temperatures, curium form compounds with the gaseous form of tellurium, selenium, and sulphur. These compounds are tellurides, selenides, and sulphides, respectively. This metal can also create its pnictides as CmX with phosphorus, antimony, arsenic, and nitrogen. Curium pnictides can be formed by the reaction between these elements and metallic curium or curium (III) hydride at escalated temperature.



Atomic Weight

Cm -240




Cm – 242


Cm – 243


Cm – 244










Cm -249


Cm – 250

250. 078

As you can see, curium has 96 electrons as well as 96 protons; hence its atomic number is also 96. The electron configuration of an element implies the arrangement of electrons in its orbits.

Electron Configuration of Curium

Configuration of Electron

[Rn] 5f7 6d1 7s2

1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6 4f14 5d10 6s2 6p6 5f7 6d1 7s2

Electrons Present Per Shell

2 8 18 32 25 9 2

Valence Electrons

5f7 6d1 7s1

Filling Orbital


Find the diagram below and check the shell model of Cm.

[Image will be Uploaded Soon]

 Let’s take a quick quiz and check how well do you know about curium!


1. What is the Inspiration of “Curium” Name?

  1. Irene-Joliot and Marie Curie

  2. Irene-Joliot and Pierre Curie

  3. Pierre and Marie Curie

  4. Marie Curie

2. Where Does Curium Belong to in the Periodic Table?

  1. Halogens

  2. Alkali metals

  3. Lanthanide series

  4. Actinide series

3. Which of the Following Options Does Curium Suggest?

  1. Non-metal

  2. Metal

  3. Semi-metal

  4. Ceramic

4. Which One is the Half-life of Cm-242 from Below?

  1. Around 163 days

  2. Around 163 seconds

  3. Around 16300 years

  4. Around 163 years

5. Which Curium Isotope Does Find Use in Pacemakers?

  1. Cm – 244

  2. Cm – 252

  3. Cm – 248

  4. Cm – 242

6. Which Device can Transfer Nuclear Energy into Electrical Energy?

  1. Thermocouples

  2. ion accelerator

  3. APXS spectrometers

  4. Salt bridges

7. What is the Neutron Number of Curium?

  1. 151

  2. 150

  3. 152

  4. 153

8. Who Identified and Discovered Cm?

  1. Glenn T. Seaborg

  2. Albert Newton

  3. Marie Curie

  4. Pierre Curie


  1. c. The inspiration of “curium” name was the names of two great physicists -Pierre and Marie Curie.

  2. d. Curium belongs to actinides series.

  3. b. Curium is a metal.

  4. a. The half-life of Cm – 242 is around 163 days.

  5. d. Cm – 242 can be found in pacemakers.

  6. c. APXS spectrometer can convert nuclear energy into electricity.

  7. a. Curium has 151 neutrons.

  8. a. Glenn T. Seaborg identified as well as found out curium.

Uses of Curium

  • Curium isotopes like Cm–242 and Cm–244 find their usages in the industry of power generation. These two isotopes are used in both thermionic and thermoelectric converters.

  • For qualitative analysis, curium is also utilised in X-ray spectrometers.

  • In biotechnology and medical application, Cm is used as a source of power such as pacemakers.

  • Curium is known as a highly radioactive metal. Due to this property, Cm finds its use in various scientific researches.

These are some crucial curium uses that you should know while learning about this metal.

Effects on Animals and Humans

  • Curium is considered as a hazardous metal. If inhaled Cm can cause several health disorders.

  • If ingested, curium can cause gastrointestinal and respiratory depressions. Moreover, it can impact adversely on the liver as well.

  • Research shows that when Cm isotope is injected in rats, they developed skeletal cancer.

  • The radioactive emission of Cm can destruct RBC or red blood cells.

If you need any further information about curium, you can simply go through the additional study materials available in our website. Or, for better understanding and doubt clearing, you can also join our online classes where you can meet our chemistry experts. 

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FAQ (Frequently Asked Questions)

1. What is the Major Usage of Curium?

Ans. Curium is mostly used for scientific researches and also as a power source. However, you can also find several use of Cm in medical fields.

2. Why is Cm Considered as a Dangerous Metal?

Ans. It is considered as dangerous metal due to its high radioactive emission. It can cause a various form of cancer to animals.

3. What Colour Can You See When Curium Glows?

Ans. When curium glows, you will notice a dark pink or purple colour. It is because of its radioactive nature.

4. What is the Actual Colour of the Curium?

Ans. It has a metallic silvery-white colour. However, it gets oxidised readily at standard temperature and slowly starts tarnishing.