Mercury: A Slippery Element Trivia Quiz

Answer: Bromine

Mercury, with a melting point of -38.9C, is the only metal which is a liquid at room temperature (defined by chemists as 20-25C), under normal atmospheric conditions, but not the only element. The other is bromine, a halogen, which is a brown liquid. There are a few metals which have melting points not much above room temperature, including cesium (28.5C), gallium (29.8C) and rubidium (39.3C). On a hot summer day, all three of these can melt.

The proviso mentioned about normal atmospheric conditions is because reducing pressure on a substance will lower the temperature required to melt it, and placing it under increased pressure will raise the melting point. This is the principle behind liquefying gases for storage in pressurised containers.

Answer: Hydrargyrum

While mercury does form small rolling balls as it moves around a smooth surface (if you are old enough, you may have tried to move a glob of mercury through a maze without letting it split into smaller pieces, before the mercury was replaced in toys by less hazardous steel balls), that is not related to its chemical symbol, which is Hg.

This is an abbreviation of its Latin name, hydrargyrum, which is a Latinized form of the Greek hydrargyros, meaning water-silver. The Anglicised form of this name is quicksilver. All of these aliases are more evocative than the usual mercury, a name chosen in reference to the Roman god, known for his speedy progress.

Answer: Medieval alchemists

According to Paracelsus (1493-1591), everything is composed of three primal substances, combined in different amounts: mercury, sulfur and salt. Each of these had a philosophical significance, with mercury being related to the spirit, sulfur to the soul, and salt to physical substance. He assigned symbols to each of them, and the symbol for mercury was the same as that used for the planet. This was later expanded to have seven metals (a number commonly seen to have significance), each associated with one of the seven planets visible to the naked eye, as well as one of the classical deities. These symbols were used in their records of their experiments, and are pretty much the same as those commonly seen in astrology. (In fact, alchemy and astrology overlapped each other quite a bit, but that's another quiz!) Mercury is the only element to use as its name in English the name of the planet with which alchemists associated it.

The link between alchemy and mercury is not restricted to European traditions - the Sanskrit word for alchemy is "Rasaśāstra", which translates as "the way of mercury". It has proved to be a slippery way, as the philosopher's stone remains an elusive goal.

Answer: Cinnabar

The other options might be of interest if you were looking for iron, lead or aluminium, but the search for mercury often ends with the red mineral cinnabar, whose chemical formula is HgS. The bright red pigment vermilion was originally made from ground cinnabar, and was widely used in Europe (for illuminated manuscripts of the Middle Ages and oil paintings of the Renaissance), in India (for the cosmetic powder sindoor used to indicate that a Hindu woman is married) and China (for a range of lacquer products from as long ago as several thousand years BCE).

Mercury also (but rarely) disguises itself in the form of corderoite, a compound of mercury, sulfur and chlorine, or livingstonite, which is composed of mercury, antimony and sulfur. Even more rarely, you can occasionally surprise it in its native state!

Answer: Hg-202

(High school level of nuclear physics here - avert your eyes if you are a scientist working in the area!) The atoms of elements are composed of a combination of protons (which give the nucleus its positive charge, and determine its chemical properties, so are used to identify the name of the element) and neutrons (which have no charge, but roughly the same mass as the protons, and which keep the positively-charged protons from pushing each other away from each other so that the nucleus breaks down). Two atoms with the same number of protons but a different number of neutrons are called isotopes. Most elements exist in nature with more than one possible isotope, although often one is by far the most common, so the average mass of a random sample will be very close to the mass of that isotope. Mercury, however, has a number of different stable isotopes, and the average mass of a sample is close to 200, because most of the stable isotopes are lighter than Hg-202, the most common one. It contains 80 protons, like all of mercury's isotopes, and 122 neutrons, for a total mass of 202 amu (atomic mass units).

Hg-171 is the lightest currently known isotope of mercury, an unstable isotope with a half-life of around 80 microseconds - don't blink, or you'll miss it! Hg-196 and Hg-209 are, respectively, the lightest and heaviest of the seven known stable isotopes. Given how rapidly observations change, they are now often listed as "observationally stable", meaning that we haven't seen them spontaneously decaying, so if they do so it is too slowly for us to detect with current techniques.

Answer: Mercury is only poisonous if mercury-containing food is eaten.

There are a number of different ways in which mercury poisoning can occur - some more obvious than others. Since the middle of the 20th century, the one with the highest profile has been the eating of fish whose flesh is contaminated by an organic compound of mercury, often methylmercury, which they have acquired either by eating smaller contaminated fish or from direct environmental exposure to mercury-polluted water.

However, in earlier times the phrase "mad as a hatter" referred to the fact that those who worked in the hatter's trade were exposed to mercury vapour during the processing stages, and suffered from consequent mercury poisoning.

Despite the known dangers posed by mercury, it was widely used in the treatment of caries (tooth decay) well into the 20th century, since the amalgam formed by combining mercury with other metals (mostly silver, tin and copper) proved an effective and relatively inexpensive way to fill holes in teeth. Contemporary dental practice avoids the use of amalgam when it is at all possible, since over time amalgam does break down, and there is a risk of low-dose mercury exposure from it.

Answer: Sulfur

If you are still using a liquid-tube thermometer rather than one based on an LCD display, you should check to see if the liquid is silver or red. If it is red, you have an alcohol-filled thermometer; if it is silver, it may be mercury, and great care should be taken in handling it. Should it break, you need to clean up the spill, and just using a cloth or paper towel won't be effective. In many places you can contact a Poisons Control Centre (or similar) for advice, and they may be able to provide a smaller version of the kits kept in commercial establishments where mercury spills are a risk. The first step is (using suitable handing devices, or wearing gloves) to coax the droplets into a single large one, which can be collected using an eyedropper or by pushing it into a small disposable container. Do not use a broom or vacuum cleaner! Once most of the mercury has been removed, any tiny residual droplets still need to be removed.

Mercury readily reacts with sulfur (were you paying attention when we discussed the fact that it is commonly found in nature as HgS?), so sprinkling sulfur flakes on the spilled liquid will cause a reaction changing it to a compound which is easier to collect than the slippery balls of metal. Kits may also contain activated carbon, a black powder which is an excellent absorbing agent, or powdered forms of metals which react readily with mercury, such as zinc (which is a grey color, not yellow). These powders, however, can pose a risk of explosive combustion, so sulfur is the most widely used product. This process only works if the mercury is on a non-porous surface, though - if you get it on your clothes, you should probably get rid of them to be on the safe side.

Answer: Silver

While there was a lot of gold being mined, it was only occasionally processed via amalgamation (although mercury was used as part of some stages in its extraction). It was for silver processing that the patio process was invented in Pachuca Mexico by Bartolome de Medina.

A slurry of crushed ore, salt, water, copper sulfate and mercury was spread into a rectangular enclosure called a patio, to a depth of around 50 cm. After several weeks of regular mixing and exposure to the sun, the silver could be removed as an amalgam, from which it could then be easily extracted.

This development led to dramatically increased production of silver (since lower-grade ores could be used than had been required for smelting), and also increased the value of mercury due to its essential role in the process.

The patio process was later replaced by more efficient amalgamation techniques, especially the pan amalgamation process, developed in 1609 in Bolivia, which heated the mixture in shallow copper vessels, reducing the processing time from weeks to less than a day.

Answer: Iron

As has been discussed earlier in the quiz, the fact that mercury readily forms an amalgam with zinc is the reason why powdered zinc can be used to treat mercury spills, and amalgamation as a part of the processing of silver revolutionised the silver trade in the 16th century. Aluminium also reacts readily, and most aircraft (which contain a lot of the light-weight aluminium in their structures) do not allow mercury anywhere in the vicinity. Aluminium is usually found covered with a protective layer of aluminium oxide, formed when the metal is exposed to the air. However, it only takes a scratch in that coating to allow mercury vapour (which forms when the liquid is exposed to the air) to contact the aluminium and start to form an amalgam. This amalgam destroys the protective oxide coat, and in a short time the airplane will start to disintegrate. Not a pleasant thought when you are planning to head up into the air!

As well as iron, there are several other metals which do not react readily with mercury, including platinum, nickel and cobalt. Iron, however, is the most practical one to use to contain the slippery stuff.

Answer: Fluorescent tubes

Fluorescent lamps typically contain a mixture of low pressure mercury vapor with a noble gas (argon, xenon, neon or krypton). The inner surface of the glass tube has a fluorescent coating whose exact formulation governs the apparent color of the light the tube produces. They operate by having an electric potential difference applied between the two ends of the tube, causing the electrodes to emit electrons and produce a current. These electrons are absorbed by the mercury atoms, which then emit light in the ultra-violet region as they return to their ground state. This UV light is what hits the tube's coating, making it glow.

In some applications, such as UV lights used in tanning beds, the glass is not coated, and the light that comes out is simply the light emitted by the mercury vapour, which usually has a blue color (since it is a mixture of frequencies from the blue and violet parts of the spectrum, as well as ultraviolet).