How Does Cadmium Affect Health and the Environment?
An Introduction to the Chemical Properties of Cadmium
In 1817, cadmium was first discovered by a German chemist, Friedrich Stromeyer as an impurity in zinc oxide. Cadmium is a highly malleable element, has an atomic number 48 and its symbol as per the periodic table in Chemistry is Cd. The average mass or weight of the atom is around 112.411, and it exists as a solid in normal room temperatures. These are the chemical properties of cadmium.
Further, if you want to learn what does cadmium means, the details below would act as your best guide.
So let us get started!
What is Cadmium?
Cadmium is a silvery-white metal with an extremely soft texture. Therefore, the metal can be moulded into any form without breaking or cracking it. It has a lower melting point around 609.92 degrees Fahrenheit or 321.07 degrees Celsius compared to other metals like zinc, and a boiling point of 767 degree Celsius.
However, it is not present in the surroundings in the form of pure metal. It is mostly available in complicated oxides, carbonates and sulphides of zinc, copper or lead.
It is an element that is toxic when humans or plants come in close contact or get exposed to. In plants, it primarily shows slow growth and development, whereas in a human body it is carcinogenic.
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Did you know: The number of isotopes present in Cadmium metal is 48.
Uses of Cadmium
Cadmium is a chemical element that is available on specific areas of the earth in small and large proportions. They get quickly dissolved in water and have a lower melting point compared to other metals, making it beneficial for multiple applications. Let us find out what is the use of cadmium from the points below.
Its applications are in power stations, metal-working industries, and heating systems, etc.
The uses of cadmium metal are also present in urban traffic.
It also gets used in alloys and jewellery along with ceramic and enamels.
The chemical properties of cadmium are beneficial for use in pigments for plastics and steel or iron plating.
It also gets used in electroplating, nickel-cadmium batteries, and plastic stabilisers.
It is present in mobile phones, cameras, computers, and cordless devices, etc.
According to what the Minerals Education Coalition believes, cadmium gets used in emergency power generation and electricity supply.
It also finds its application in nuclear rods to maintain the nuclear reactions within a limit as it can absorb neutrons.
Compounds containing cadmium also finds its applications in the picture tube of a television.
Cadmium, along with other compounds like tellurium, is ideal for applications in solar cell production as they are relatively cost-effective.
Moreover, cadmium is an essential element used in electroplating, and formation of different varieties of solder.
Fun Facts: As per the Agency for Toxic Substances and Disease Registry, batteries contain around 83% of cadmium, whereas around 8% gets used in pigments. Approximately, 7% of cadmium has applications in coatings, 1% gets used in plastics and the remaining 1% in alloys.
Effects of Cadmium
Cadmium (Cd), a zinc by-product has the potential to alter the health of a human being and plants when they come in close contact with them. It is present within our surroundings at low levels. However, its excessive exposure can result in adverse effects on the biotic species, and the primary sources result from the consumption of tobacco and food.
Read some of the effects of the chemical properties of cadmium from below.
Human Beings:
Cadmium (Cd) is highly toxic for a human body when they come in exposure while working. After it gets absorbed in a person, it remains in them throughout the entire life.
The chemical properties of cadmium are initially hazardous to the renal organs (kidneys) and its proximal tubular cells when it accumulates at first.
It is an element that has the potential to cause reduction of minerals in bones, resulting from bone damage or renal dysfunction.
Due to excessive exposure of humans to cadmium in industries and factories, it can cause potential damage to the proper functioning of the lungs. Also, it can be a threat to humans as it can result in lung cancer.
Furthermore, it can result in skeletal and respiratory problems in a person with prolonged exposure to industrial emissions of cadmium.
It also gets described as a human carcinogen because it can promote cancer cells in a body.
Pregnant women exposed to cadmium have the possibility of bearing children with low weight at birth.
Extreme inhalation of this metal over a short time can result in symptoms of flu, such as chills, fever and acute pain in the muscles.
Plants:
If you know about what are the uses of cadmium, then you must be aware that the emissions of this material adversely impact a plant’s growth.
Primarily, it hampers with the transfer and uptake of various elements in plants, such as calcium, potassium, magnesium and water, etc.
It gets recognised as a potential pollutant since it is highly water-soluble and extremely toxic. Plants absorb this metal and show retarded development.
The metal can be responsible for the change of mineral’s uptake by plants.
Moreover, it has been visible that stomata opening and synthesis of food particles get affected by cadmium absorption.
If you are aware of what is cadmium used in, you must understand that its continuous emission affects transpiration process in plants.
Chlorosis or incapability of a plant to produce sufficient chlorophyll is visible in plants due to intake of this toxic metal.
Besides, leaf rolls and restriction results as an impact of the chemical properties of cadmium.
It also reduces the nitrate absorption and its transfer from roots to other parts of plants, through nitrate reductase activity.
Further, the metal disturbs the chloroplasts mechanism, and it reduces the enzyme’s activities in plants.
Ways to Reduce the Risk of Exposure to Cadmium
There is a potential threat when you get exposed to a higher level of cadmium within a short time. However, one can control the risk of exposure to this toxic metal following the below points:
It is highly advisable to stop smoking as cigarette smoke generates cadmium that can get accumulated in the lungs.
If your working environment requires the handling of cadmium, it is always better to use protective measures.
Give yourself a regular check on your cadmium levels by visiting a doctor.
Facts to Learn about Cadmium
The countries China, Mexico, United States, Korea, Netherlands, Germany, and India get counted as the most significant producers of cadmium.
Mostly, cadmium has its applications in those areas where zinc gets refined instead of mining.
As per the International Cadmium Association, Germany was the sole provider of the element Cd, till World War 1.
According to International Cadmium Association, the metal was earlier used in red, orange and yellow paints due to bright hue.
As per to what Jefferson Laboratory believes, cadmium derives its name from a Latin name cadmia and a Greek name kadmeia. These words relate to an ancient name of zinc carbonate.
The density of the Cd metal is 8.69 g (grams) per cubic centimetre.
Since it is an excellent electrical conductor, it finds an application in electroplating, and they are an integral component in batteries.
It does not occur in nature in abundance, and Greenockite is the single mineral that contains cadmium.
As per the Geological Survey of the United States, the ratio at which cadmium is available in zinc ores ranges from 200:1 to 400:1 (zinc to cadmium ratio).
Cadmium is highly water-soluble, and it gets quickly dissolved in vegetables and plants.
It is hazardous to all biotic species, and it can lead to cadmium poisoning.
Cadmium is carcinogenic in a human body as it can cause lung cancer.
Studying the above facts regarding the chemical properties of cadmium should clear up your concepts on this chapter. If you intend to learn more on such engaging Chemistry concepts, login into our Vedantu app today for a better learning experience.
FAQs on Cadmium in Chemistry: Properties, Uses, and Effects
1. What are the key physical and chemical properties of cadmium that students should know?
Cadmium (Cd), with atomic number 48, is a soft, malleable, and ductile silvery-white metal. Key properties include:
- Physical Properties: It has a relatively low melting point (321°C) and boiling point (767°C). It is a good conductor of electricity and is highly resistant to corrosion.
- Chemical Properties: As a divalent metal, it typically forms a +2 oxidation state in its compounds. It is chemically similar to zinc and mercury, its neighbours in Group 12 of the periodic table. It readily reacts with acids but is insoluble in alkalis.
2. What are the most important industrial uses of cadmium?
The primary applications of cadmium are driven by its unique properties. The most important uses include:
- Batteries: Cadmium is a critical component in nickel-cadmium (Ni-Cd) rechargeable batteries, valued for their long life and reliability in devices like power tools and emergency lighting.
- Electroplating: Due to its excellent corrosion resistance, cadmium is used to coat steel, iron, and other metals, especially in the aerospace and marine industries.
- Pigments: Cadmium compounds like cadmium sulfide (CdS) are used to create vibrant and stable yellow, orange, and red pigments for paints, plastics, and glass.
- Nuclear Reactors: It acts as a neutron absorber, used in control rods to regulate nuclear fission.
3. What are the major health effects associated with cadmium exposure?
Cadmium is a toxic heavy metal, and exposure can lead to severe health problems. The primary effects are on the kidneys and bones. Chronic exposure can cause kidney damage, leading to renal failure. It interferes with calcium metabolism, which can result in bone softening (osteomalacia) and increased fracture risk. Inhaling high concentrations of cadmium can cause acute lung damage, and it is classified as a human carcinogen, linked to lung and prostate cancer.
4. Why is cadmium considered a d-block element but not a true transition metal?
Cadmium is a d-block element because its last electron enters the d-orbital. However, it is not considered a true transition metal. A transition metal is defined as an element that has an incompletely filled d-orbital in its ground state or in any of its common oxidation states. Cadmium's ground state electronic configuration is [Kr] 4d¹⁰ 5s². In its most common +2 oxidation state (Cd²⁺), its configuration is [Kr] 4d¹⁰. Since its d-orbital is completely filled in both its atomic and common ionic state, it does not meet the definition of a transition metal, similar to zinc and mercury.
5. How does cadmium enter the environment and the human food chain?
Cadmium enters the environment through both natural and industrial processes. Natural sources include volcanic eruptions and the weathering of rocks. However, industrial activities like mining, smelting, battery manufacturing, and the burning of fossil fuels are the main contributors. Once in the soil and water, cadmium is easily absorbed by plants. This process, known as bioaccumulation, causes it to enter the food chain. Foods like leafy vegetables (spinach, lettuce), root vegetables (potatoes), cereals, and shellfish can accumulate significant levels of cadmium, becoming a primary source of dietary exposure for humans.
6. What is the biochemical mechanism that makes cadmium so toxic, particularly to the kidneys?
Cadmium's toxicity stems from its ability to disrupt cellular processes. Its primary mechanism involves its interaction with sulfhydryl (-SH) groups in enzymes and proteins, inactivating them. In the kidneys, cadmium binds to the protein metallothionein. While this initially offers protection, when the kidneys' capacity to produce this protein is overwhelmed, free cadmium ions cause severe damage to the renal tubules. This damage impairs reabsorption, leading to the excretion of essential molecules like proteins, glucose, and amino acids in the urine, and disrupts calcium metabolism, affecting bone health.
7. How is cadmium extracted from its ores?
Cadmium does not have its own principal ore. It is most commonly found in small quantities within zinc ores, such as sphalerite (ZnS). Therefore, its extraction is a byproduct of zinc refining. During the smelting or electrolytic refining of zinc, cadmium, being more volatile, is separated from zinc. It can be collected from the flue dust of smelters or from the residues of electrolytic zinc production. The collected cadmium is then purified through processes like distillation or electrolysis to achieve a high-purity metal.
8. Why was cadmium historically used in jewellery, and what are the risks?
Cadmium was used in jewellery, particularly in alloys and for soldering, because it has a lower melting point, making it easier to work with. It could also add weight and a bright finish to pieces. However, its use is now highly restricted or banned in many countries due to its toxicity. The primary risk is that cadmium can leach from the jewellery and be absorbed through the skin or ingested if the jewellery comes into contact with the mouth, posing a significant health hazard to the wearer.
