Mercury (element) facts for kids

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Pouring liquid mercury bionerd
Mercury

Mercury, also known as quicksilver or hydrargyrum, is a chemical element. Its symbol on the periodic table is Hg, and its atomic number is 80. Its atomic mass is 200.59

The symbol Hg stands for its Latinized Greek name hydrargyrum, meaning watery or liquid silver.

History

Mercury symbol
The symbol for the planet Mercury (☿) has been used for a very long time to represent the element

No one has the credit for finding mercury. It was found in ancient history. Mercury was found in Egyptian tombs that are from 1500 BC. Chinese people also knew it from long ago. In China and Tibet, people thought using mercury would make them live longer and have better health. One of China's emperors, Qín Shǐ Huáng Dì, is said to have been buried in a tomb with rivers of flowing mercury. He was killed by drinking a mixture of mercury and powdered jade because he wanted to live forever. However, this only made him die of liver failure, poisoning, and brain death. The ancient Greeks used mercury in ointments. The Egyptians and the Romans used it in cosmetics. These cosmetics sometimes hurt and made faces uglier.

Properties

Physical properties

Mercury is a silvery-white liquid post-transition metal. The reason for mercury being a liquid is quite complex. It is quite heavy; a chunk of iron can float on mercury. Compared to other metals, it does not conduct heat well. However, it conducts electricity fairly well. Mercury is the only metal with a known melting point (−38.83 °C) lower than caesium. Mercury is one of the two elements that are liquids at room temperature and normal pressure. Bromine is the other one.

Mercury may be seen as a transition metal, but it is normally seen as a post-transition metal. It is in Group 12 of the periodic table. Mercury has seven stable (nonradioactive) isotopes. 202Hg is the most common isotope. Mercury makes a blue to ultraviolet color in a tube when a spark is passed through it. The ultraviolet light can kill germs.

Chemical properties

Mercury is an unreactive metal. It does not corrode in air unless hydrogen sulfide is also there, similar to silver. Mercury can oxidize to mercury(II) oxide when heated in air. If it is heated further, it decomposes into mercury and oxygen again. It does not dissolve in ordinary acids, but can dissolve in oxidizing acids to make mercury salts. It can make amalgams when mixed with most metals, like aluminium, gold, and zinc. Iron, tantalum, tungsten, and platinum do not make amalgams with mercury. Iron flasks were used to trade mercury because of this.

Mercury can dissolve large amounts of aluminium metal, making it dangerous to transport in aluminium containers. The thin layer of oxide on aluminium stops it from amalgamating (making an amalgam with) aluminium, but the oxide coating can be damaged to expose the metal. Then the aluminium metal is dissolved and oxidizes to aluminium oxide. The aluminium oxide forms a solid and releases the mercury, which amalgamates more aluminium. This process keeps repeating until a large amount of aluminium is dissolved.

Chemical compounds

Mercury chloride,
possibly mercury(I) chloride
Mercury(II) oxide
Cinnabar, mercury(II) sulfide
Mercury(I) chloride as a mineral
Mercuryfulminate puryfied
Mercury(II) fulminate

Mercury forms chemical compounds in 2 oxidation states: +1 and +2. Mercury(I) compounds are weak oxidizing agents and weak reducing agents. Most of them are colorless. They easily disproportionate to mercury(II) compounds and mercury metal. They react with oxygen in the air to make mercury(II) compounds. Many mercury(I) compounds do not dissolve in water. Mercury(I) chloride is one of the most common mercury(I) compounds. Mercury(II) compounds are strong oxidizing agents and very corrosive. Mercury(II) compounds are red, yellow, or colorless. Mercury(II) oxide and mercury(II) chloride are the most common mercury(II) compounds in the laboratory.

One thing they have in common is that they are all toxic. The soluble ones are more toxic than the insoluble ones.

Mercury(I) compounds

Also known as mercurous compounds, these are weak reducing agents and weak oxidizing agents. Most of them do not dissolve in water, making them less toxic than mercury(II) compounds. Most of them are colorless or yellow.

Mercury(II) compounds

Also known as mercuric compounds, these are strong oxidizing agents. Most of them dissolve in water, making them very toxic. They are colorless or red.

Organomercury compounds

These contain mercury reacted with a organic molecule. They are even more toxic than other mercury compounds since they get absorbed very easily.

Occurrence

Mercury-27128
Small blobs of liquid mercury as an element along with streaks of cinnabar
Mercury-61215
Another rock with liquid mercury on it

Mercury is a rare metal. It is about as common as silver. Mercury is not expensive like silver because the mercury is very easy to get from the places where it is found. Mercury can be found in elemental (liquid) form in nature, but this is not common. Mercury as an element is the only liquid that is recognized as a mineral by the International Mineralogical Association. It is most often found in the form of cinnabar, a mercury(II) sulfide mineral. The biggest deposits of cinnabar used to be found in Spain, but now are found in China. It also occurs in other minerals like calomel, a mercury(I) chloride mineral.

Preparation

China and Kyrgyzstan are the two main makers of mercury. Mines in Italy, the United States, and Mexico have been closed. China is opening more mines because the European Union wants to use fluorescent lights, which need mercury.

Mercury is made by roasting cinnabar in a furnace. The sulfide is oxidized to sulfur dioxide, leaving mercury behind.

Uses of mercury

Toxicity

Mercury is liquid at room temperature, and fumes of mercury are very poisonous. Ingested elemental mercury is less dangerous. The biggest problems are organic mercury compounds which are eaten with food. However, inorganic compounds such as mercury(II) nitrate are also highly toxic by ingestion (eating) or inhalation (breathing in) of the dust. Mercury can cause both chronic and acute poisoning.

In the year 1810, over 200 people died of mercury poisoning on the ship Triumph because a barrel of mercury had leaked.

Mercury is extremely poisonous and has to be used carefully. When mercury is spilled, there are special ways to clean it up. Smaller drops should be combined to a larger drop on hard surfaces to be removed more easily (for example, being pushed into a bag that can be thrown away). Vacuum cleaners and brooms should not be used. This is because they can spread mercury even more. Afterwards, elements such as sulfur or zinc powder should be sprinkled over the place, then collected and cleaned away. It is not easy to clean mercury entirely off clothing, so it is better not to use them anymore. Breathing in mercury vapor is also very dangerous.

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Mercury (element) Facts for Kids. Kiddle Encyclopedia.