Gallium
Gallium is a soft, silvery metal famous for an unusual party trick: it melts at a temperature only slightly above room temperature, turning to liquid in a warm hand. Beyond the novelty, it's become a critical material in modern semiconductors and LED lighting.
- Group · Period
- 13 · 4
- At room temp
- solid
- Melts at
- 302.91 K
- Density
- 5.91 g/cm³
- Discovered
- 1875
Uses
Gallium’s most important modern role is in semiconductors: compounds like gallium arsenide and gallium nitride are used in high-frequency electronics, laser diodes, and especially LEDs, where gallium nitride enabled the development of efficient blue and white light-emitting diodes now standard in screens, lighting, and displays. Because of its unusually low melting point, gallium is also used in specialized thermometers and certain low-melting alloys that stay liquid near room temperature.
Its low toxicity compared with some other metals has also made gallium useful in certain medical imaging applications and alloys designed to replace more hazardous materials like mercury.
History
Gallium’s existence was predicted before it was found: in 1871, Dmitri Mendeleev used a gap in his periodic table to describe a missing element he called “eka-aluminum,” estimating several of its properties in advance. In 1875, French chemist Paul-Émile Lecoq de Boisbaudran detected a new element spectroscopically in a sample of zinc ore, and after isolating it, found its properties matched Mendeleev’s prediction closely. He named the new element gallium, after Gallia, the Latin name for France, honoring his home country.
Fun facts
- Gallium melts at just under 30°C, low enough that a solid piece can turn to liquid simply from the warmth of holding it in your hand.
- It was predicted years before its discovery, when Dmitri Mendeleev described a missing element he called 'eka-aluminum' based on gaps in the periodic table.
- Gallium compounds like gallium nitride are essential to modern LED lighting, including the blue and white LEDs used in most screens and light bulbs today.
Frequently asked questions
Why does gallium melt so easily compared to other metals?
Gallium's atoms form unusually weak bonds in its solid structure compared with most metals, so relatively little energy is needed to break those bonds and let it flow as a liquid. That's why it melts at a temperature you'd never associate with a metal — well below the boiling point of water, and easily reached by body heat.
How did Mendeleev predict an element that hadn't been discovered yet?
Mendeleev arranged the known elements by their properties and found that certain gaps in the pattern implied missing elements with specific, predictable characteristics. He described one such gap as "eka-aluminum," estimating its density and other properties. When gallium was found a few years later, its measured properties matched his prediction closely, which was a striking validation of the periodic table itself.
Why is gallium important for LEDs?
Compounds like gallium nitride and gallium arsenide are semiconductors with electronic properties well suited to converting electricity directly into light efficiently. Gallium nitride in particular made practical blue LEDs possible, which was the missing piece needed to create white LED lighting and full-color LED displays, a breakthrough significant enough to earn a Nobel Prize.
Compounds
1 notable compound containing Ga
- GaAssemiconductor
Gallium arsenide
A crystalline compound semiconductor with the zinc-blende structure common to many III-V materials, prized for its ability to emit and absorb light directly. It underlies much of modern high-speed and optoelectronic device technology.
Used for: LEDs, laser diodes, solar cells, and high-frequency transistors
Isotopes
29 known isotopes
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| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Ga-69 stable | 60.108% | Stable | — | -69,327.82 keV | 8,724.58 keV | — |
| Ga-71 stable | 39.892% | Stable | — | -70,139.13 keV | 8,717.61 keV | — |
Show all 29 isotopes
| Ga-59 | — | 43 ns | Proton emission | -33,760 keV | 8,232 keV | 1.06 × 10-8 eV |
| Ga-60 | — | 70 ms | Electron capture / beta-plus decay (100%), Beta-plus, proton emission (1.6%), Beta-plus, alpha emission (0.023%) | -39,590 keV | 8,327 keV | 6.52 × 10-15 eV |
| Ga-61 | — | 167 ms | Electron capture / beta-plus decay (100%), ECP (0.25%) | -47,134.66 keV | 8,446.43 keV | 2.73 × 10-15 eV |
| Ga-62 | — | 116.121 ms | Electron capture / beta-plus decay (100%), ECP | -51,987.02 keV | 8,518.64 keV | 3.93 × 10-15 eV |
| Ga-63 | — | 32.4 s | Electron capture / beta-plus decay (100%) | -56,547.1 keV | 8,583.93 keV | 1.41 × 10-17 eV |
| Ga-64 | — | 2.627 m | Electron capture / beta-plus decay (100%) | -58,832.83 keV | 8,611.63 keV | 2.89 × 10-18 eV |
| Ga-65 | — | 15.2 m | Electron capture / beta-plus decay (100%) | -62,657.49 keV | 8,662.16 keV | 5.00 × 10-19 eV |
| Ga-66 | — | 9.49 h | Electron capture / beta-plus decay (100%) | -63,723.73 keV | 8,669.36 keV | 1.34 × 10-20 eV |
| Ga-67 | — | 3.2617 d | Electron capture (100%) | -66,879.16 keV | 8,707.53 keV | 1.62 × 10-21 eV |
| Ga-68 | — | 67.71 m | Electron capture / beta-plus decay (100%) | -67,086.05 keV | 8,701.22 keV | 1.12 × 10-19 eV |
| Ga-70 | — | 21.14 m | Beta-minus decay (99.59%), Electron capture (0.41%) | -68,910.15 keV | 8,709.28 keV | 3.60 × 10-19 eV |
| Ga-72 | — | 14.10 h | Beta-minus decay (100%) | -68,588.28 keV | 8,687.09 keV | 8.99 × 10-21 eV |
| Ga-73 | — | 4.86 h | Beta-minus decay (100%) | -69,699.34 keV | 8,693.87 keV | 2.61 × 10-20 eV |
| Ga-74 | — | 8.12 m | Beta-minus decay (100%) | -68,049.63 keV | 8,663.17 keV | 9.36 × 10-19 eV |
| Ga-75 | — | 126 s | Beta-minus decay (100%) | -68,460.64 keV | 8,660.76 keV | 3.62 × 10-18 eV |
| Ga-76 | — | 32.6 s | Beta-minus decay (100%) | -66,296.65 keV | 8,624.53 keV | 1.40 × 10-17 eV |
| Ga-77 | — | 13.2 s | Beta-minus decay (100%) | -65,992.35 keV | 8,613.39 keV | 3.46 × 10-17 eV |
| Ga-78 | — | 5.09 s | Beta-minus decay (100%) | -63,704.09 keV | 8,577.1 keV | 8.96 × 10-17 eV |
| Ga-79 | — | 2.848 s | Beta-minus decay (100%), Beta-minus, neutron emission (0.089%) | -62,548.36 keV | 8,556.07 keV | 1.60 × 10-16 eV |
| Ga-80 | — | 1.9 s | Beta-minus decay (100%), Beta-minus, neutron emission (0.86%) | -59,223.68 keV | 8,508.45 keV | 2.40 × 10-16 eV |
| Ga-81 | — | 1.217 s | Beta-minus decay (100%), Beta-minus, neutron emission (11.9%) | -57,627.96 keV | 8,483.36 keV | 3.75 × 10-16 eV |
| Ga-82 | — | 0.600 s | Beta-minus decay (100%), Beta-minus, neutron emission (22.2%) | -52,930.73 keV | 8,421.05 keV | 7.60 × 10-16 eV |
| Ga-83 | — | 308.1 ms | Beta-minus decay (100%), Beta-minus, neutron emission (62.8%) | -49,257.13 keV | 8,372.58 keV | 1.48 × 10-15 eV |
| Ga-84 | — | 95.2 ms | Beta-minus decay (100%), Beta-minus, neutron emission (46%), B-2N (1.6%) | -44,094.14 keV | 8,307.53 keV | 4.79 × 10-15 eV |
| Ga-85 | — | 92 ms | Beta-minus decay (100%), Beta-minus, neutron emission (35%) | -39,744.06 keV | 8,253.57 keV | 4.96 × 10-15 eV |
| Ga-86 | — | 43 ms | Beta-minus decay (100%), Beta-minus, neutron emission (60%), B-2N (20%) | -33,760 keV | 8,182 keV | 1.06 × 10-14 eV |
| Ga-87 | — | 634 ns | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -28,870 keV | 8,124 keV | 7.20 × 10-10 eV |