{"id":165,"date":"2020-04-09T09:44:11","date_gmt":"2020-04-09T09:44:11","guid":{"rendered":"https:\/\/thechemicalelements.com\/?page_id=165"},"modified":"2023-08-15T16:04:43","modified_gmt":"2023-08-15T16:04:43","slug":"cadmium","status":"publish","type":"post","link":"https:\/\/thechemicalelements.com\/cadmium\/","title":{"rendered":"Cadmium (Cd)"},"content":{"rendered":"\n

Cadmium (Cd) is a chemical element with an atomic number of 48 in the periodic table of elements<\/a>. Found in Earth\u2019s crust at about 0.5 ppm (parts per million), it belongs to the group of rare metals. As a member of both the transition and toxic metals family of periodic table elements, this naturally occurring soft metal has two valence electrons that make cadmium relatively unreactive with the other chemical elements.\u00a0<\/span><\/p>\n\n\n\n

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Chemical and Physical Properties of Cadmium<\/span><\/h3>\n\n\n\n
Property<\/strong><\/td>Value<\/strong><\/td><\/tr>
Symbol<\/td>Cd<\/td><\/tr>
Name<\/td>Cadmium<\/td><\/tr>
Atomic number<\/td>48<\/td><\/tr>
Atomic Mass<\/td>112.411 g.mol-1<\/td><\/tr>
Group<\/td>Metal<\/td><\/tr>
Period<\/td>5<\/td><\/tr>
Color<\/td>Silvery-grey with a blue metallic hue<\/td><\/tr>
Physical state<\/td>A soft metal at room temperature<\/td><\/tr>
Half-life<\/td>38+ years<\/td><\/tr>
Electronegativity<\/td>1.69<\/td><\/tr>
Density<\/td>8.65 g.cm-3 at 20\u00b0C<\/td><\/tr>
Melting point<\/td>321 \u00b0C<\/td><\/tr>
Boiling point<\/td>767 \u00b0C<\/td><\/tr>
Van der Waals radius<\/td>158 pm<\/td><\/tr>
Ionic radius<\/td>.95 (+2) \u00c5<\/td><\/tr>
Atomic weight<\/td>112.411 g.mol-1<\/td><\/tr>
Most characteristic isotope<\/td>48Cd<\/td><\/tr>
Electronic shell<\/td>[Kr] 4d10 5s2<\/td><\/tr>
The energy of the first ionization<\/td>866 kJ.mol-1<\/td><\/tr>
The energy of the second ionization<\/td>1622 kJ.mol-1<\/td><\/tr>
Discoverer<\/td>Fredrich Stromeyer<\/td><\/tr>
Year<\/td>1817<\/td><\/tr>
Location<\/td>Germany<\/td><\/tr>
Uses<\/td>Used in nickel-cadmium batteries, electroplating steel, manufacture of bearings, paint pigments.<\/td><\/tr>
Description<\/td>Rare, very soft, silver-white metal<\/td><\/tr>
Shells<\/td>2,8,18,18,2<\/td><\/tr>
Orbitals<\/td>[Kr] 4d10 5s2<\/td><\/tr>
Valence<\/td>2<\/td><\/tr>
Crystal Structure<\/td>Hexagonal<\/td><\/tr>
Covalent Radius<\/td>1.48 \u00c5<\/td><\/tr>
Atomic Radius<\/td>1.71 \u00c5<\/td><\/tr>
Atomic Volume<\/td>13.1 cm\u00b3\/mol<\/td><\/tr>
Name Origin<\/td>Greek: kadmeia (ancient name for calamine (zinc oxide))<\/td><\/tr>
Pronounced<\/td>KAD-me-em<\/td><\/tr>
Oxydation States<\/td>2<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

With the periodic table symbol Cd, atomic number 49, atomic mass of 112.41 g.mol -1, and electronic configuration [Kr] 4d<\/span>10<\/span> 5s<\/span>2<\/span>, cadmium is soft, ductile, malleable, burns to redness when exposed to heat, and has a deep yellow vapor. <\/span><\/p>\n\n\n\n

It reaches its boiling point at 767 \u00b0C, while the melting point is achieved at 321 \u00b0C, which is lower than the transition metals arranged in the groups from 3 through 11 in the periodic table. <\/span><\/p>\n\n\n\n

This member of the transition metals family of elements in the periodic table has an electronegativity of 1.69 according to Pauling, whereas the atomic radius according to van der Waals is 158 pm. <\/span><\/p>\n\n\n\n

With oxidation states of +1 and +2, cadmium undergoes tarnishing as a result of its exposure to air (especially to oxygen<\/a> – O2). It’s dissolved in acids, but not in alkalis. <\/span><\/p>\n\n\n\n

When cadmium is dissolved by hydrochloric acid, nitric acid, or sulfuric acid, the resulting compounds are cadmium chloride (CdCl2), cadmium nitrate (Cd(NO3)2), and cadmium sulfate (CdSO4), respectively.\u00a0 In addition, this transition metal has strong anti-corrosive properties.<\/span><\/p>\n\n\n\n

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How Was Cadmium Discovered?<\/span><\/h2>\n\n\n\n

In the 17th century, zinc<\/a> oxide was often used for the treatment of various skin conditions. In 1817, the German physician and a professor at the University of G\u00f6ttingen, Friedrich Stromeyer (2 August 1776 \u2013 18 August 1835), was asked by the government to inspect the Hildesheim pharmacies suspected of selling zinc carbonate instead of zinc oxide.<\/span><\/p>\n\n\n\n

So, Stromeyer attempted an experiment by heating zinc carbonate taken from the pharmacies in an effort to prove the impurity of the substance sold by the pharmacies in this German town. He was expecting the white carbonate to turn into a white oxide, but instead, it ended up being yellow. <\/span><\/p>\n\n\n\n

Since he could not trace any other elements that would give this color to the resulting oxide (such as lead or iron<\/a>), this German chemist continued researching which led him to the place where the local pharmacies were obtaining the chemical substance, but he didn\u2019t get any information that would clarify his scientific dilemma. <\/span><\/p>\n\n\n\n

This led him to another experimental attempt when he reduced the elemental form of cadmium as the new, yellow-tinting substance of the analyzed zinc oxide rising from the yellow vapor from the soot and zinc oxide mixture. This turned out to be a completely new chemical element, and that\u2019s how he discovered the elemental form of cadmium. <\/span><\/p>\n\n\n\n

The same year, two other scientists, the German chemist Karl Samuel Leberecht (1765 – 1846) Hermann and the German physicist and apothecary Johann Christoph Heinrich Roloff (1783 – 1825), also succeeded in isolating cadmium in its elemental form, but Friedrich Stromeyer was accepted in the scientific world as the first discoverer of this member of the transition metals family of chemical elements.\u00a0<\/span><\/p>\n\n\n\n

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How Did Cadmium Get Its Name?<\/span><\/h2>\n\n\n\n

\u201cKadmeia\u201d is the Greek word used as a reference to zinc oxide. It was used to label the chemical element with an atomic number of 48 (Cd) due to the fact that cadmium is mainly obtained by heating zinc ores (Zn).\u00a0<\/span><\/p>\n\n\n\n

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Where Can You Find Cadmium?<\/span><\/h2>\n\n\n\n

This chemical element is rarely found in Earth’s crust but is nonetheless widely distributed in nature. Cadmium occurs as a by-product of zinc ores, among which zinc blende (or sphalerite) is the main cadmium smelting ore. Greenockite (CdS) is the only crystal form of cadmium consisting of cadmium sulfide. <\/span><\/p>\n\n\n\n

It also occurs in some lead ores and in a small number of minerals, combined with oxygen, chlorine<\/a>, or sulfur. China, Kazakhstan, Japan, Canada, and South Korea comprise the group of the world\u2019s leading countries in cadmium production. In the United States, cadmium is mostly obtained as a by-product of zinc, lead<\/a>, or copper<\/a>. Mineral deposits of this chemical element are found in Washington, Utah, Missouri, Colorado, and Illinois. <\/span><\/p>\n\n\n\n

Some foods, such as oil-seeds, shellfish, fish, and leafy vegetables, also contain low-levels of cadmium.\u00a0<\/span><\/p>\n\n\n\n

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Cadmium in Everyday Life<\/span><\/h2>\n\n\n\n

Despite being a rare metal, cadmium is widely used in everyday life for producing rechargeable batteries (more specifically, the rechargeable Ni-Cd batteries), solar cells, UV lamps, TV tubes (both black and white, and in color), bearings, in cadmium stabilizers, cadmium telluride solar panels, etc. <\/span><\/p>\n\n\n\n

Furthermore, due to its strong anti-corrosive properties, cadmium is used as an electroplating agent in the making of airplanes and all other vehicles and machines that can be damaged by corrosion. By electroplating cadmium onto alloys containing iron, steel, brass, or copper, this substance serves as protection from corrosion. <\/span><\/p>\n\n\n\n

The control rods made of cadmium often find their use in the work of nuclear reactors due to their ability to absorb neutrons. Cadmium salts are applied in the production of pigments, where cadmium selenide (also known as cadmium red) produces a red pigment, while cadmium sulfide produces a yellow pigment.\u00a0\u00a0\u00a0\u00a0<\/span><\/p>\n\n\n\n

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How Dangerous Is Cadmium?<\/span><\/h2>\n\n\n\n

This chemical element belongs to the category of toxic metals. Due to its high toxicity and adverse health effects, cadmium is less and less applied in everyday life. The general population is exposed to cadmium mainly through cigarette smoke, food containing cadmium, soldering, welding, etc. <\/span><\/p>\n\n\n\n

This toxic metal has been labeled by the <\/span>European Restriction of Hazardous Substances Directive<\/span><\/a>, the <\/span>United States Department of Health and Human Services<\/span><\/a>, <\/span>Human Services National Institute for Occupational Safety and Health<\/span><\/a>, and the <\/span>Agency For Toxic Substances and Disease registry<\/span><\/a> as a human carcinogen. <\/span><\/p>\n\n\n\n

Namely, cadmium exposure can have adverse health effects on multiple systems of the body, such as the gastrointestinal system, the reproductive system, the immune system, the nervous system, the respiratory system, the urinary system, and the kidneys. <\/span><\/p>\n\n\n\n

Basically, the long-term exposure to high levels of this substance classified as a human carcinogen may result in kidney diseases leading to permanent kidney damage, lung cancer, etc.\u00a0<\/span><\/p>\n\n\n\n

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Cadmium Poisoning <\/span><\/h3>\n\n\n\n

The inhalation of cadmium vapor or dust is especially <\/span>toxic<\/span><\/a>. Cadmium poisoning can occur after consuming contaminated food, drinking water, or inhaling air contaminated with high levels of this heavy metal.<\/span><\/p>\n\n\n\n

By accumulating in the kidneys, this toxic substance impairs our biological mechanism that filters the waste products of the body and regulates both the production of red blood cells and hormones.\u00a0\u00a0<\/span><\/p>\n\n\n\n

What Are the Risk Factors of Cadmium Poisoning?<\/span><\/h4>\n\n\n\n

Exposure to even low levels of cadmium concentration can lead to adverse effects on human health, which can develop into cancer and have a fatal outcome. The risk factors that trigger these adverse health effects include:<\/span><\/p>\n\n\n\n