Mercury is one of the most interesting and dangerous chemical elements in the periodic table. This silvery-white metal is liquid at room temperature, which distinguishes it from most other metals. Mercury’s atomic number is 80 , meaning that each mercury atom contains 80 protons in its nucleus. This article provides an overview of mercury’s atomic number, its chemical and physical properties, its uses, its discovery history, and its effects on the environment and health.
What is the atomic number of mercury?
The atomic number of an element indicates the number of protons in its atomic nucleus . Mercury, for example, has an atomic number of 80, which means it has 80 protons in its nucleus. This number is used to determine mercury’s position in the periodic table
. According to its atomic number, mercury is located in the 6th period, group 12 , and its chemical symbol is Hg , derived from the Latin word hydrargyrum, meaning “liquid silver”.
Atomic structure and mass number of mercury
A mercury atom contains 80 electrons, distributed across different energy levels around the atomic nucleus. The electron configuration of mercury is as follows:
[Xe] 4f¹⁴ 5d¹⁰ 6s²
This electron configuration shows that the d and f subshells of mercury are completely filled, making the mercury atom relatively stable and resistant to chemical reactions. The mass number of naturally occurring mercury isotopes is typically around 200.59 , which is a weighted average of the various mercury isotopes from Hg-196 to Hg-204.
Physical properties of mercury
Mercury is one of the few metals that is liquid at room temperature . Its physical properties include:
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Order number: 80
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Relative atomic mass: 200.59 units
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Melting point: -38.83 degrees Celsius
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Boiling point: 356.73 degrees Celsius
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Density at room temperature : 13.534 g/cm³
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Color and appearance: Silver, shiny, liquid.
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Electrical conductivity: high
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Evaporation rate: relatively high at room temperature.
Because of these properties, mercury was used in the past to manufacture thermometers, barometers, and electrical switches.
Chemical properties of mercury
Mercury is relatively chemically stable . It does not react with many acids at room temperature , but it does react with strong oxidizing agents such as nitric acid (HNO₃) and concentrated sulfuric acid (H₂SO₄) . These reactions typically produce mercury(II) oxide (HgO) or its salts , such as mercury(II) nitrate (Hg(NO₃)₂) .
Mercury has two main oxidation states:
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Hg⁺ (monovalent mercury )
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Hg²⁺ (mercury)
Compounds of divalent mercury are more stable and occur more frequently in nature.
Mercury isotopes
Mercury has several stable isotopes, the best known of which are:
| Take a closer look | Natural population ratio | Mass number |
|---|---|---|
| Mercury-196 | 0.15% | 196 |
| Mercury-198 | 10.04% | 198 |
| Mercury-199 | 16.94% | 199 |
| Mercury-200 | 23.14% | 200 |
| Mercury-201 | 13.17% | 201 |
| Mercury-202 | 29.74% | 202 |
| Mercury-204 | 6.82% | 204 |
The number of neutrons in the atomic nuclei of these isotopes varies, but the number of protons (80) is constant in all of them. This constant number of protons determines the chemical properties of mercury.
Use of mercury
Mercury was widely used in various industries in the past due to its unique properties. Today, its use is restricted or banned in many countries because of its extreme toxicity . Traditional and industrial applications of mercury include, but are not limited to:
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Thermometers and barometers: because they expand uniformly when the temperature changes.
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Mercury vapor lamp: emits high-intensity white light.
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Mercury switches and relays: are used in sensitive electrical circuits.
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Gold extraction: Formation of a gold mixture.
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Production of chlorine and sodium hydroxide (NaOH): in an old-fashioned electrolysis cell.
For most of these applications, safer alternatives have since been proposed .
The effects of mercury on the environment and health
Despite its importance in science and industry, mercury is considered extremely dangerous from an environmental and health perspective. Mercury vapor and its compounds, especially methylmercury (CH₃Hg⁺) , easily enter the human body through inhalation or ingestion . The accumulation of mercury in the body can lead to the following diseases:
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Damage to the central nervous system
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Kidney disease
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fetal developmental disorders
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Vision and hearing problems
Therefore, international organizations such as the World Health Organization and the United Nations Environment Programme have imposed strict restrictions on the use and disposal of mercury.
History of the discovery of mercury
Mercury has been known to humankind since antiquity. In ancient Egypt and China , it was used in traditional medicine and even in religious rituals.
The name “mercury” derives from the Roman god of commerce and travel, as mercury, due to its high fluidity and brilliant luster, was associated with this deity. Medieval alchemists considered mercury an essential element capable of transmuting base metals into gold
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The position of Mercury in the periodic table
| Special feature | Crowd |
|---|---|
| Chemical symbols | mercury |
| ordinal number | 80 |
| pool | 12 |
| turn | 6 |
| siege | D |
| category | Transition metals |
| At room temperature | fluid |
Mercury belongs to group 12, the same group as zinc (Zn) and cadmium (Cd), and is similar to them in atomic structure and chemical properties.
Interesting facts about mercury
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Mercury is the only metal that exists in a liquid state at room temperature.
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Freezes at temperatures below -38.83 degrees Celsius .
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In ancient dentistry, gold, silver, and amalgam were used.
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Liquid mercury has a very smooth and shiny surface.
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Its atomic number (80) is one of the highest among the stable elements .
In conclusion
Mercury’s atomic number (80) is fundamental to understanding the behavior and properties of this unique element. Due to its distinctive electron configuration, mercury is a heavy, shiny, liquid metal that was once widely used for a variety of purposes. However, its use is now severely restricted due to its hazardous properties.