Lithium Element Properties
Complete reference for Lithium (Li, element 3): atomic data, electron configuration, isotopes, physical constants, and chemical behavior.
Lithium
Alkali Metal — Period 2, Group 1
Atomic Identity
Electron Configuration
One unpaired electron in 2s
Isotopes of Lithium
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Natural Abundance | Stability |
|---|---|---|---|---|---|---|
| Lithium-6 | ⁶Li | 3 | 3 | 6.01512289 | 7.59% | Stable |
| Lithium-7 | ⁷Li | 3 | 4 | 7.01600344 | 92.41% | Stable |
| Lithium-8 | ⁸Li | 3 | 5 | 8.02248624 | Radioactive |
Unstable
β⁻ decay, t½ = 840.3 ms |
| Lithium-9 | ⁹Li | 3 | 6 | 9.02679019 | Radioactive |
Unstable
β⁻ decay, t½ = 178.3 ms |
Physical Properties
Chemical Properties
Ground State Quantum Numbers
Notable Emission Lines
Lithium produces a distinctive crimson-red flame in a flame test, primarily from the 670.78 nm doublet transition.
Key Facts About Lithium
Lightest Metal
At 0.534 g/cm³, lithium is the least dense metal and the least dense solid element at standard conditions. It is light enough to float on water — though it reacts vigorously with it.
Battery Technology
Lithium has the highest electrochemical potential of any element (−3.04 V), making it essential for rechargeable lithium-ion batteries that power phones, laptops, and electric vehicles.
Crimson Flame Test
Lithium compounds burn with a bright crimson-red flame, one of the most distinctive of all the alkali metals. This property is used to identify lithium in qualitative analysis.
Medicinal Use
Lithium carbonate and lithium citrate are mood-stabilizing medications prescribed for bipolar disorder. Lithium is one of the few elements with an established role in psychiatric medicine.
Nuclear Applications
Lithium-6 is used in thermonuclear weapons as lithium deuteride and in tritium production. Lithium-7 is used as a pH buffer in pressurized water reactors in nuclear power plants.
Big Bang Nucleosynthesis
Along with hydrogen and helium, lithium was synthesized in the first few minutes after the Big Bang. Observed stellar lithium abundances provide important tests of cosmological models.
Summary
Complete reference for Lithium (Li, element 3): atomic data, electron configuration, isotopes, physical constants, and chemical behavior.
How it works
- Browse the atomic identity section for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and quantum numbers.
- Review the isotopes table for lithium-6 and lithium-7 data including natural abundance.
- Consult the physical properties panel for melting point, density, and state at STP.
- Use the chemical properties section to understand alkali metal behavior and ionization energies.
- Copy any value with one click for use in reports or calculations.
Use cases
- Look up lithium constants for chemistry homework or exams.
- Verify atomic data when writing lab reports.
- Reference isotope masses for nuclear chemistry or battery research.
- Check thermodynamic constants for materials science or engineering.
- Teach or learn alkali metal properties starting with the lightest metal.
- Confirm electron configuration before writing molecular orbital diagrams.
- Compare lithium-6 and lithium-7 properties for nuclear or pharmaceutical research.
- Quick-reference ionization energy for electrochemistry or spectroscopy work.