Chem Explorers

Cadmium: The Valuable Element with Hidden Risks

Cadmium – The Chemical That Excels in Stability and Resistance

Cadmium (Cd) is a rare, bluish-grey element that is soft, malleable, and ductile. It has a stable electronic configuration with an outermost s2p6 d10 electron shell configuration, which means it is highly resistant to oxidation and corrosion.

In this article, we will explore the chemical properties of cadmium, its physical characteristics, and its chemical classification in detail. Occurrence and Obtaining Cadmium:

Cadmium is not abundant in the earth’s crust and is mostly present as a by-product of zinc production.

Zinc ores are the primary source of cadmium, and it is obtained via the smelting of zinc ores. Since the impurities in the ores are eliminated in the refining process, cadmium is usually obtained from the residues of the refining process.

Physical Characteristics of Cadmium:

The physical characteristics of cadmium are unique and make it an important element for industrial applications. Cadmium is a soft, bluish-grey metal with a shiny finish.

It is ductile, which means it can be stretched into a wire. Cadmium is also malleable, which means it can be pounded into thin sheets without breaking.

Cadmium is inflammable and does not ignite when exposed to air or water. Melting, Boiling Point, and Density of Cadmium:

The melting point of cadmium is 594.22 K (321.07 C), while the boiling point is 1040 K (766.85 C).

The density of cadmium is 8.65 g/cm3, which is less than that of its closest neighbors zinc and mercury. Cadmium Symbol, Group, Period, and Block in the Periodic Table:

The symbol of cadmium is Cd, and it belongs to group 12 of the periodic table.

It is a d-block element located in the 5th period of the periodic table. Cadmium Isotopes and Electronic Configuration:

Cadmium has eight isotopes, with the most stable being 114Cd, 111Cd, and 112Cd. Cadmium has a stable electronic configuration with a full s2p6 d10 shell configuration.

Cadmium Oxidation States and Electronegativity:

Cadmium has two oxidation states, +2 and +1, with a preferential +2 oxidation state. The electronegativity of cadmium is 1.69, which is higher than that of its closest neighbor, zinc.

Cadmium Ionization Energies:

The first ionization energy of cadmium is 867.8 KJ/mol, the second ionization energy is 1631.4 KJ/mol, and the third ionization energy is 3616 KJ/mol. The high third ionization energy indicates that cadmium is highly resistant to the removal of its electrons.

Cadmium CAS Number, ChemSpider ID, and Chemical Classification:

The CAS registry number for cadmium is 7440-43-9, while its ChemSpider ID is 22399. The CAS number and ChemSpider ID are unique identifiers that are used to track specific chemical substances in various databases.

Cadmium is classified as a transition metal and is part of the zinc group of elements. In conclusion, cadmium is a rare and valuable element with unique physical and chemical properties.

Its resistance to oxidation and corrosion makes it an important material in various industrial applications, including batteries and electronic devices. The ability of cadmium to resist breaking and deformation makes it an ideal element for use in high-temperature applications.

By understanding its properties, we can utilize cadmium effectively and efficiently.

Uses and Applications of Cadmium

Cadmium is a valuable element often used in industries due to its remarkable properties, including its resistance to oxidation and corrosion. Some of the common uses and applications of cadmium include its use in rechargeable nickel-cadmium batteries, electroplating, and semiconductors.

However, because cadmium is toxic and carcinogenic and poses threats to the environment, there are risks associated with its use. As such, there are established regulations and guidelines on the use and disposal of cadmium.

Common Uses and Applications of Cadmium:

Rechargeable Nickel-Cadmium Batteries – Cadmium found its first commercial application in nickel-cadmium batteries (NiCd batteries) in the early 1900s. NiCd batteries are used in various applications, including portable electronics like cell phones, PDAs, laptops, power tools, and toys, as they have a high energy density and long life.

Electroplating – Cadmium is used in electroplating, a process by which a thin layer of cadmium is applied onto a metal surface to improve the surface’s properties, such as improving corrosion resistance or enhancing aesthetics. Cadmium electroplating is used in many industries, including aerospace, automotive, and military, for coating bolts, gears, and other components.

Semiconductors – Cadmium is used to manufacture semiconductors for electronic devices such as photovoltaic (PV) cells, infrared detectors, and transistors. Cadmium sulphide is a popular semiconductor material for solar cells because of its high absorption coefficient, which makes it an efficient absorber of solar energy.

Risks and Hazards of Cadmium Exposure:

Cadmium is known to be toxic and carcinogenic to humans and animals. Prolonged exposure to high levels of cadmium can lead to kidney failure, lung damage, and other serious health problems.

Cadmium can also cause cancer, particularly lung and prostate cancers. Moreover, cadmium can contaminate soil and water and enter the food chain, posing environmental risks.

Regulations and Guidelines on the Use and Disposal of Cadmium:

Due to the health risks and environmental implications of cadmium, there are established regulations and guidelines on its use and disposal. Occupational exposure limits (OELs) for cadmium have been set to reduce the risks of exposure to workers.

In the United States, the Occupational Safety and Health Administration (OSHA) has set a permissible exposure limit (PEL) of 5 g/m3 for cadmium in the air of workplaces. Waste disposal regulations vary by region, but generally, cadmium waste should be disposed of in specialized landfills or incineration facilities.

In the European Union, the use of cadmium in consumer applications, such as electronics and batteries, has been regulated since 2006 through the Restriction of Hazardous Substances (RoHS) directive. The RoHS directive restricts the use of cadmium along with other hazardous substances such as lead, mercury, and hexavalent chromium.

In conclusion, cadmium is a valuable element with several industrial applications, including its use in rechargeable nickel-cadmium batteries, electroplating, and semiconductors. However, exposure to cadmium poses health risks to humans, and cadmium contamination can have severe environmental implications.

The established regulations and guidelines on the use and disposal of cadmium are essential for protecting workers’ safety and the environment, ensuring that cadmium is used responsibly with minimal impact on human health and the environment. Cadmium is a valuable element with unique physical and chemical characteristics, utilized in various industries due to its resistance to corrosion and high-temperature applications.

Some common applications of cadmium include its use in rechargeable nickel-cadmium batteries and electroplating. However, the risks associated with the toxic and carcinogenic nature of cadmium compounds require appropriate regulations and guidelines to ensure proper disposal and protection for workers.

Cadmium poses a significant threat to human health and the environment, which makes it imperative to utilize it responsibly while minimizing its impact.


Q: What are some common uses of cadmium?

A: Cadmium finds use in rechargeable nickel-cadmium batteries, electroplating, semiconductors, and alloys. Q: Why is cadmium toxic?

A: Cadmium is toxic because it accumulates within the body and can lead to health problems involving the kidneys, liver, lungs, bones, and heart. Q: What are some of the environmental risks associated with cadmium?

A: Cadmium exposure can cause soil and water contamination and ultimately result in negative impacts on the ecosystem. Q: Are there established regulations on cadmium use and disposal?

A: Yes, there are regulations and guidelines on cadmium use and disposal, which are essential for minimizing the impact on workers’ safety and the environment.

Q: Can cadmium be recycled?

A: Yes, cadmium can be recycled from discarded devices such as batteries, to reduce waste and to prevent environmental contamination.

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