62 Sm Samarium 150.36
Lanthanide f-block Period 6

Samarium

Sm · Element 62

A rare earth whose magnets keep working at temperatures that destroy neodymium.

STATE AT 20°C Solid
ATOMIC MASS 150.36 u
ELECTRON CONFIGURATION [Xe] 4f⁶ 6s²
61Pm All 118 63Eu

Structure

The samarium atom

Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.

Orbital cloud

Measured values

Property sheet

Every bar shows where samarium sits among all 118 elements for that property.

Physical

Density 7.52 g/cm³ 49%
Melting point 1345 K 61%
Boiling point 2067 K 45%
Specific heat 0.197 J/g·K
Thermal conductivity 13.3 W/m·K 39%

Atomic

Atomic radius 180 pm 66%
Covalent radius 198 pm
Van der Waals radius 229 pm

Electronic

Electronegativity 1.17 18%
Ionisation energy 538.4 kJ/mol 12%
Electron affinity 48.2 kJ/mol 31%

Occurrence

Abundance in crust 7.05 mg/kg 67%

Identity

SymbolSm
Atomic number62
Atomic mass150.36 u
CategoryLanthanide
Blockf
Crystal structurerhombohedral
Oxidation states+2, +3
Discovered1879
Discovered byLecoq de Boisbaudran

Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.

Size, to scale

How big is a samarium atom?

Radius 180 pm — that is 0.18 nm, so about 2778 million of them side by side would span a millimetre.

Thermal range

Solid, liquid, gas — and when

Samarium is liquid over a 722 K window, from 1345 K to 2067 K.

Where it sits

Position in the table

Samarium sits in the lanthanide series, printed below the main grid.

OTHER LANTHANIDES

57La 58Ce 59Pr 60Nd 61Pm 63Eu 64Gd 65Tb 66Dy 67Ho 68Er 69Tm 70Yb 71Lu
All lanthanides

The story

What samarium is, and how we found it

A rare earth whose magnets keep working at temperatures that destroy neodymium.

The discovery of samarium

🔬 French Scientific Triumph

Paul-Émile Lecoq de Boisbaudran (1879)

French chemist Paul-Émile Lecoq de Boisbaudran discovered samarium while investigating the mineral samarskite from North Carolina. Using his pioneering spectroscopic techniques, he detected new spectral lines that couldn't be attributed to known elements.

Spectroscopic Detection

Boisbaudran employed flame spectroscopy to analyze rare earth concentrates, observing characteristic orange-red emission lines at wavelengths never before recorded. His meticulous observations and systematic approach established samarium as the first rare earth element discovered through spectroscopic analysis.

Naming Origins

The element was named after samarskite mineral, which itself honored Russian mining engineer Colonel Vasili Samarsky-Bykhovets. This made samarium the first element named after a living person, though indirectly through the mineral name.

Isolation Challenges

Pure samarium metal wasn't isolated until 1901 by Eugène-Anatole Demarçay, who used electrochemical reduction of samarium chloride. The 22-year gap between discovery and isolation demonstrates the technical challenges of rare earth element purification.

Industrial Development

Commercial samarium production began in the 1960s with the development of ion exchange separation techniques. The discovery of samarium-cobalt magnets by Albert Daane and Kenneth Strnat in 1966 transformed samarium from a laboratory curiosity into a strategically important material.

Scientific Impact

Samarium's discovery contributed to:

  • Rare earth chemistry understanding
  • Spectroscopic technique development
  • Periodic table completion
  • Lanthanide series characterization
🏆 Scientific Legacy: Boisbaudran's discovery methods established spectroscopy as the primary tool for identifying new elements, revolutionizing analytical chemistry.

Applications

What samarium is used for

🧲 Magnetic Technology Revolution

Samarium stands as one of the most strategically important rare earth elements, driving innovations in high-performance magnets, nuclear technology, and advanced materials science. Its unique magnetic and neutron-absorbing properties make it central for modern technology.

Super-Strong Permanent Magnets

Samarium-cobalt (SmCo) magnets represent a high point of permanent magnet technology, maintaining magnetic strength at temperatures up to 350°C where neodymium magnets fail. These magnets power precision motors in satellites, military guidance systems, and high-end audio equipment.

Nuclear Reactor Control

Samarium-149 possesses the highest thermal neutron absorption cross-section of any stable nucleus, making it crucial for nuclear reactor control rods. This isotope naturally accumulates in reactor cores as a fission product, requiring careful management in reactor physics calculations.

Advanced Cancer Treatment

Samarium-153 serves as a radiopharmaceutical for treating bone cancer metastases. The isotope's targeted accumulation in bone tissue and controlled beta emission provides precise therapeutic radiation while minimizing damage to healthy organs.

Precision Optics and Lasers

Samarium-doped glasses create specialized optical components for infrared applications, including night vision systems, laser range finders, and fiber optic communications. The element's sharp absorption lines enable precise wavelength filtering.

Catalytic Processes

Samarium catalysts facilitate carbon-carbon bond formation in organic synthesis, particularly in pharmaceutical manufacturing. Samarium diiodide (SmI₂) enables unique reduction reactions impossible with conventional catalysts.

⚡ Innovation Driver: Samarium-cobalt magnets enable the miniaturization of high-performance motors, making possible everything from precision robotics to ultra-efficient wind turbines.

⚙️ Everyday Technology Applications

Electric Vehicle Motors

High-performance electric vehicles utilize samarium-cobalt magnets in their drive motors due to exceptional temperature stability and power density. These magnets maintain efficiency during rapid acceleration and high-speed operation.

Aerospace Applications

Commercial and military aircraft rely on samarium-cobalt magnets in actuators, sensors, and navigation equipment. The magnets' resistance to demagnetization at altitude and temperature extremes ensures reliable operation in aerospace environments.

Medical Devices

MRI machines incorporate samarium compounds in contrast agents for enhanced imaging of specific tissues. Samarium's magnetic properties improve image resolution and diagnostic accuracy for certain medical conditions.

Audio Equipment

High-end speakers and headphones feature samarium-cobalt magnets in their drivers, producing superior sound quality with minimal distortion. Audiophiles prize these components for their exceptional magnetic stability and acoustic performance.

Industrial Motors

Manufacturing equipment uses samarium-based permanent magnet motors for precision positioning, high-speed machining, and automated assembly systems. These motors offer exceptional efficiency and controllability.

Consumer Electronics

Smartphones, tablets, and laptops contain micro-motors with samarium magnets for camera autofocus, haptic feedback, and cooling fans. The miniaturization enabled by these powerful magnets allows for thinner, more efficient devices.

📈 Growing Demand

  • Renewable energy generation systems
  • Electric vehicle charging infrastructure
  • Advanced robotics and automation
  • Next-generation telecommunications equipment

Where it comes from

Natural occurrence

7.05 mg/kg of Earth's crust · more abundant than 67% of elements

🌍 Global Rare Earth Deposits

Primary Mineral Sources

Samarium occurs primarily in monazite and bastnäsite deposits, typically comprising 1-8% of rare earth element content. The largest economically viable deposits are located in China (Bayan Obo), the United States (Mountain Pass, California), and Australia (Mount Weld).

Geological Formation

Samarium concentrates in alkaline igneous rocks and associated pegmatites through magmatic differentiation processes. Carbonatite complexes, formed by carbon dioxide-rich magmas, contain the highest samarium concentrations due to preferential fractionation during crystallization.

Geographic Distribution

Significant samarium resources exist in:

  • China: Inner Mongolia deposits (60% of global production)
  • United States: California and Alaska rare earth mines
  • Australia: Western Australian laterite deposits
  • India: Monazite beach sands along Kerala coast
  • Brazil: Minas Gerais state mineral complexes

Extraction Challenges

Samarium separation requires complex multi-stage processes involving ion exchange, solvent extraction, and fractional crystallization. The similarity of lanthanide chemical properties makes purification energy-intensive and technically demanding.

Environmental Considerations

Rare earth mining often involves radioactive thorium and uranium co-extraction, requiring specialized waste management. Environmental protection measures include groundwater monitoring, tailings pond management, and air quality control systems.

Supply Chain Security

Global samarium supply concentration in few countries creates strategic materials concerns for technology-dependent nations. Recycling programs and alternative source development are increasingly important for supply security.

📊 Crustal Abundance: Samarium occurs at approximately 6 parts per million in Earth's crust, making it more abundant than tin but rarer than copper.

Handling

Safety

⚠️ Moderate Hazard Handling

Physical Hazards

Samarium metal presents fire risks when finely divided, igniting spontaneously in air above 150°C. Metal chips and powder require storage under inert atmosphere to prevent oxidation and potential combustion.

Chemical Reactivity

Samarium reacts slowly with water and acids, producing hydrogen gas and heat. Avoid contact with strong oxidizing agents, which can cause vigorous reactions. Samarium compounds may cause skin and eye irritation upon direct contact.

Personal Protection

  • Safety glasses and face shield for powder handling
  • Chemical-resistant gloves (nitrile or neoprene)
  • Laboratory coat and closed-toe shoes
  • Dust mask or respirator when generating particles

Safe Handling Practices

Work in well-ventilated areas or fume hoods when handling samarium compounds. Use grounding straps and anti-static procedures when working with powders. Keep incompatible materials separated and clearly labeled.

Storage Requirements

Store samarium metal under mineral oil or inert gas to prevent oxidation. Compounds should be kept in tightly sealed containers in cool, dry locations away from acids and oxidizers. Maintain temperature below 25°C for optimal stability.

Emergency Procedures

Fire incidents: Use dry sand, sodium chloride, or Class D fire extinguishers. Never use water on samarium metal fires. Chemical spills: Neutralize with mild acid, absorb with inert material, and dispose according to regulations.

✅ Low Toxicity: Samarium has relatively low acute toxicity but should be handled with standard laboratory safety precautions to prevent accumulation exposure.

Quick answers

Samarium: common questions

What is Samarium?

Samarium (symbol Sm) is element 62 on the periodic table, a lanthanide in period 6. A rare earth whose magnets keep working at temperatures that destroy neodymium. At room temperature it is a solid.

What is the electron configuration of Samarium?

Samarium's ground-state electron configuration is [Xe] 4f⁶ 6s², giving 6 occupied shells holding 2, 8, 18, 24, 8, 2 electrons respectively.

What are the melting and boiling points of Samarium?

Samarium melts at 1345 K (1071.9 °C) and boils at 2067 K (1793.9 °C).

What is the atomic mass of Samarium?

The standard atomic weight of Samarium is 150.36 u. That is a weighted average across its naturally occurring isotopes, which is why it is rarely a whole number.

How dense is Samarium?

Samarium has a density of 7.52 g/cm³. Water is 1.0 g/cm³, so a block of samarium is about 7.5× heavier.

What is the electronegativity of Samarium?

Samarium has a Pauling electronegativity of 1.17. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). A value this low means it readily gives its outer electrons away, forming positive ions.

Who discovered Samarium, and when?

Samarium was discovered in 1879 by Lecoq de Boisbaudran. It is named after the mineral samarskite.

How common is Samarium on Earth?

Samarium makes up about 7.1 mg/kg of the Earth's crust — uncommon, but not rare.

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