Gallium is a soft, silvery metal with symbol Ga and atomic number 31. It can sit solid on a cool desk, then melt from your hand. That trick comes from a melting point only a little above room temperature. Once melted, pure gallium remains liquid over an unusually large temperature range before boiling at a very high temperature.
Reference tables do not all use the same boiling point. The NIST Chemistry WebBook lists gallium phase data that anchor melting in calibration work. The NIH PubChem gallium page draws on U.S. national laboratory write-ups and quotes a Jefferson Lab block near 2477 K (about 2204°C) while also carrying Los Alamos material that rounds boiling near 2400°C. Treat about 2200 to 2400°C as a literature band, not a contest over the last digit.
Those traits matter beyond demos. Gallium feeds high-purity melting-point standards, specialty thermometry, and a family of compounds used in modern electronics.
Gallium metal stays solid at 20-25°C, then melts near 30°C
Gallium is usually listed as a solid at 20 to 25°C, but it melts at about 29.76°C in many laboratory summaries. The NIST Chemistry WebBook recommends a fusion temperature of 302.92 K for gallium, about 29.8°C. That is only a few degrees above a cool office.
The PubChem gallium record packages numbers and notes from national-lab contributors. One block cites a density near 5.91 g/cm³ and a melting point near 302.91 K (29.76°C), aligned with the NIST fusion value.
Liquid gallium can remain below its freezing point until crystallization is triggered, often by contact with a crystal seed. That supercooling habit makes timing-based demos feel dramatic.
Solid gallium expands by about 3.1% when it freezes. Because of that, it should not be stored in rigid containers that could crack or rupture. Los Alamos notes reproduced on PubChem tell the same story as the stand-alone national-lab page.
Metrology, gallium compounds, and gallium-based alloys
NIST documents reference materials tied to the gallium melting point for temperature work, which is why metrology shows up next to classroom clips. Gallium and especially gallium-based alloys have been used in temperature measurement and calibration; practical liquid-column setups today often rely on alloys that stay liquid near room temperature, not always pure gallium, which freezes near 30°C.
In electronics and optoelectronics, compounds such as gallium arsenide and gallium nitride matter for LEDs, high-frequency parts, and some laser-related designs. PubChem’s overview ties gallium to semiconductor doping and solid-state devices. Industry-facing mineral surveys from the U.S. Geological Survey, summarized in the references below, chiefly discuss gallium as an imported commodity tied to compound uses in circuits and optoelectronics, which frames why chemists track the metal even when the public only sees ingots online.
In 1875 the French chemist Paul-Émile Lecoq de Boisbaudran identified gallium spectroscopically, aligning with what Dmitri Mendeleev had sketched for his predicted eka-aluminum. Encyclopedias such as Britannica retell that episode in fuller detail.
Hands-on gallium: surfusion, mirror films, and the aluminum caution
The Wikipedia article on gallium notes that liquid gallium wets skin and many surfaces, which makes cleanup messy, and it summarizes how liquid gallium can attack and weaken aluminum by penetrating the metal, including everyday foil or hardware. Treat that as a lecture-hall caution, not a home project. Los Alamos notes that gallium can wet glass or porcelain and form a mirror-like film when spread on glass, a classic demonstration when institutional safety rules allow it.
Popular demo videos show melting and reshaping gallium, including hands-on clips still easy to find under the DaveHax name (see Sources). Viewers should follow supplier safety instructions, keep samples away from aluminum, and avoid ingestion.
This article does not replace a safety data sheet, a teacher’s risk assessment, or legal guidance on chemical purchases.
What you can do next
Use the linked references if you discuss gallium in a newsletter, a classroom, or a makerspace brief. If you buy metal samples, read supplier safety documents before opening the package. Gallium is not handled like mercury, but it is still a chemical substance that should be labeled, kept away from food use, and handled according to supplier safety documents.
Sources and related information
NIST – NIST Chemistry WebBook gallium phase data – 1987
The phase-change table records a recommended gallium fusion temperature near 302.92 K, which supports the article’s focus on calibration-grade melting data.
NIST – Standard Reference Material 1751 gallium melting-point standard – 2011
The SRM certificate PDF documents gallium as a fixed-point reference for melting-point standards work, which supports the metrology subsection.
NIH PubChem – Gallium element record – n.d.
PubChem collects melting and boiling points, density, Los Alamos notes on supercooling and expansion, and a short uses overview, matching the properties and behavior sections.
Royal Society of Chemistry – Gallium element page – n.d.
The RSC periodic entry summarizes gallium as a soft metal with low melting point and lists key uses in compounds, backing general-reader framing about the element’s feel and tech ties.
Los Alamos National Laboratory – Gallium periodic table entry – 2021
The laboratory page gives melting and boiling summaries, warns about supercooling and expansion on freezing, and notes glass wetting with mirror films, especially for the storage and demo bullets.
USGS – Gallium statistics and information – n.d.
The National Minerals Information Center tracks gallium as an imported commodity tied chiefly to compound uses in electronics, supporting the industry-facing sentence without adding new numeric claims.
Encyclopedia Britannica – Gallium – n.d.
Britannica names Paul-Émile Lecoq de Boisbaudran’s 1875 spectroscopic discovery, links the name to France, and connects gallium to Mendeleev’s predicted eka-aluminum, matching the history sentences in the main text.
Wikipedia – Gallium – n.d.
The overview summarizes wetting behavior and documents that liquid gallium can weaken aluminum through penetration, which supports the cautionary “fun fact” without replacing peer-reviewed materials studies for quantitative claims.
Fisher Scientific – Safety data sheet gallium – n.d.
One representative supplier sheet lists harmful-if-swallowed language and corrosion warnings toward metals, matching the tone the article uses for handling guidance.
DaveHax – Gallium hands-on video tutorials – n.d.
The long-running hands-on gallium clips from DaveHax illustrate melting and molding for a general audience, which matches the article’s note that demos should stay secondary to supplier safety rules.
