Did you know you can melt gallium in your hand safely? Gallium is a metal, but its melting point is very low (29.7646 °C or 85.5763 °F). In its pure form, the metal is non-toxic, so it’s safe to handle. Here is how to melt gallium in the palm of your hand, along with ideas for other science projects using this interesting element.
Materials to Melt Gallium in Your Hand
All you need to melt gallium in your hand is a reasonably pure chunk of the element.
- Gallium
- Plastic gloves (optional)
Gallium does not exist free in nature. It results from the purification of other metal ores. You won’t find it in a store, but it’s available online for around $20.
While skin contact with gallium is safe, there are two reasons why you might want to wear gloves anyway. First, gallium wets skin. Contact gives skin a grayish cast that isn’t necessarily easily washed away. Second, gallium damages metals. If you normally wear a ring, either remove it before holding gallium or else wear gloves to protect it from discoloration.
How to Melt Gallium in Your Hand
Place a chunk of gallium in the palm of your hand and let body heat do all the work. Gallium melts almost immediately in a very warm room, but it may take 3-5 minutes to melt a coin-sized piece of metal in a cool room.
Feel free to tilt your hand and watch the metal flow. When you are finished, cup your hand and pour the gallium into a container. If the container is also warm, watch for metal crystal formation as the element cools. Gallium displays an orthorhombic crystal structure. Its crystal facets are not sharp like you see in other metals, but have a sort of soft, melted appearance. Over time, the shiny metal surface dulls as an oxide layer builds.
Repeat the project as many times as you like. Gallium is a pure element, so it’s not going anywhere.
Gallium Science Projects
What else can you do with gallium? There are many other gallium science projects:
- Disappearing spoon: Make a gallium spoon. You can purchase a mold, but you’ll get the same effect if you carefully pour melted gallium over the back of a chilled plastic spoon so the metal takes its shape. The gallium spoon stirs a cool liquid just fine. But, if you stir hot water, the gallium spoon melts away.
- Gallium pencil: Gallium is a soft metal. It’s soft enough to mark paper. Try using a piece of gallium metal as a pencil.
- Conchoidal fracture: One identifying characteristic of metals and compounds is how they fracture. Pour a pool of melted gallium and let it cool into a flat shape. Break the metal to see the way it fractures. One method is placing the disk in a plastic bag and striking it with a hammer. Unlike most metals, gallium breaks with a conchoidal fracture pattern. Another material displaying this type of fracture pattern is glass.
- Gallium crystals: Like bismuth, gallium readily forms metal crystals as it cools. Get the best crystals by slowly cooling it from a liquid. Pour melted gallium onto a warm container. One method is dropping a tiny bit of solid gallium onto the liquid as a seed crystal to promote growth. A second method causes instantaneous crystallization. Like water and “hot ice“, gallium displays supercooling. This means it sometimes remains a liquid well below its freezing point. If you slowly cool the liquid without bumping it, you can suddenly crystallize the metal by touching it.
- Gallium-aluminum alloy: Demonstrate the way gallium attacks metals and forms alloys with them. Pour melted gallium onto a sheet of aluminum foil. After about 30 minutes, pick up the sheet of foil by its edges, leaving behind a chunk of gallium-aluminum alloy. Examine the behavior of this new material and compare differences in it properties from pure aluminum or pure gallium. Does it melt as easily? Does it form crystals?
- Gallium mirror: One interesting gallium property is its ability to wet glass and form a mirror. Pour a bit of melted gallium onto a pane of clear glass. Tilt the glass around to coat its surface.
Safety Information
Toxicity
Melting gallium in your hand safely isn’t so much about your personal health as it is about protecting your tools and other objects. Gallium metal is non-toxic. Unlike mercury, gallium has a low vapor pressure so it goes not get into the air. Gallium does form toxic compounds with nonmetals, but even then it is excreted in urine and does not accumulate as a poison. So, don’t mix gallium with other chemicals (like bleach or lye, for example) just to see what happens!
Reaction With Metals
Gallium readily forms alloys with other metals. Do not store it in a metal container or use metal tools you care about (spoons, hammers, etc.) because it will weaken the metal. It immediately discolors and damages metal jewelry.
Storage
Ideally, store gallium in a plastic container. Gallium attacks metals and wets glass. But, there is another consideration. Gallium is one of a handful of elements (like silicon, germanium, bismuth, and plutonium) that expands as it solidifies. This means liquid gallium can rupture its container as it cools.
References
- Greber, J. F. (2012). “Gallium and Gallium Compounds” in Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a12_163
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- Kean, Sam (2010). The Disappearing Spoon: And Other True Tales of Madness, Love, and the History of the World from the Periodic Table of the Elements. Boston: Little, Brown and Company. ISBN 978-0-316-05164-4.
- Strouse, Gregory F. (1999). “NIST realization of the gallium triple point”. Proc. TEMPMEKO. 1999 (1): 147–152.
- Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. ISBN 0-8493-0464-4.