Cadmium

By Heather Nguyen

Basic Information

  • Symbol- Cd
  • Atomic Number 48
  • Atomic Mass-112.41
  • Atomic Radius- 161 pm
  • Transition Metal
  • Protons: 48
  • Neutrons: 64
  • Electrons:48

Cadmium Introduction

Cadmium - Periodic Table of Videos

History

Friedrich Stromeyer was a government official who was responsible for inspecting pharmacies. He saw that many pharmacies were stocking zinc carbonate instead of zinc oxide. The supply of zinc oxide was low and it was hard to make. In order to make zinc oxide, zinc carbonate had to be heated. A supplier of zinc oxide explained that the zinc carbonate turned yellow when it was heated. Pharmacies would no buy yellow zinc oxide so instead they replaced it with white zinc carbonate instead. Stromeyer analyzed the strange yellow zinc carbonate and discovered that the yellow pigments in the heated zinc carbonate was from cadmium. Cadmium caused the zinc carbonate to turn yellow when it was heated. The name of cadmium is the ancient name of zinc oxide, cadmia.

Physical Properties

Cadmium is slivery bluish-gray with a metallic look. The density of Cadmium is 8.65 grams per cubic centimeter. The melting point is 321.07°C(609.93°F) and its boiling point is 767°C (1413°F). At room temperature, Cadmium remains a solid. It's easily malleable and it has a high conductivity since it's a metal. It can easily be scratched with a fingernail.

Chemical Properties

Cadmium has a high reactivity with acids. It reacts slowly with oxygen in moist air at room temperatures. Cadmium does not react with water. It's very highly flammable in powder form or dust form. It is highly flammable and explosive and may ignite spontaneously in air or when exposed to heat.

Uses

At first, the most important use of cadmium was in the electroplating of steel. Cadmium is used in rechargeable batteries and is used in alloys for bearing. It is uses in low melting alloys. Sometime cadmium is a component of many kinds of solder. Compounds containing cadmium are used in black and white television phosphors. Also, it used in blue and green phosphors for color television picture tubes. Cadmium sulfide is known to be a yellow pigment, while cadmium selenide is known as a red pigment. It's often called cadmium red. Cadmium has physical characteristics that are ideal for solar cell production.

Isotopes

Cadmium has eight naturally occurring isotopes. They are cadmium-106, cadmium-108, cadmium-110, cadmium-111, cadmium-112, cadmium-113, cadmium-114, and cadmium-116. About 20 radioactive isotopes of cadmium are known. A radioactive isotope is one that breaks apart and gives off some form of radiation. One isotope of cadmium, cadmium-109, is used to analyze metal alloys. It provides a way of keeping track of the alloys in stock and sorting different forms of scrap metal. All these isotopes can be classified as metals or oxides. All can be sulfate except for cadmium-112.

Compounds

The most popular types of cadmium compounds are used as coloring agents. Some examples are cadmium sulfide and cadmium selenide. These compounds are used to color paints and plastics. There is concern about possible environmental effects of using cadmium for this purpose. Other types of cadmium compounds include cadmium mercury sulfide, cadmium oxide, cadmium nitrate, and cadmium sulfate. Most of these compounds are acids such as cadmium acetate, cadmium carbonate, and cadmium nitrate.

Health Effects

Humans are effected mostly from cadmium by cigarette smoking, shellfish, liver, kidney meats, coal burning, and contaminated water. The most dangerous way of risking your health with cadmium is people who work directly with the metal. Places including manufacturing plants were batteries are made us cadmium as a fine powder where it can be easily inhaled. Cadmium is very dangerous when it get into the ground and groundwater from buried landfills. The cadmium contaminates the food and water in the community. Even without high contact with cadmium, low levels can cause nausea, vomiting, and diarrhea. Cadmium dust is dangerous because when inhaled, it causes dryness of the throat, choking, headache, pneumonia like symptoms, and death. Manufacturing workers with extensive cadmium exposure are at risk for heart and kidney disease, high blood pressure, and cancer.

Information Citations

Element Card: Gray, Theodore W. (2008). The Photographic Card Deck of the Elements.



Elements Book: Gray, Theodore W. (2009). The Elements: A visual exploration of every known atom in the universe. New York: Black Dog & Leventhal Publishers, Inc.


Agency for Toxic Substances & Disease Registry: http://www.atsdr.cdc.gov/substances/toxsubstance.asp?toxid=15


Safety and Health Topics: https://www.osha.gov/SLTC/cadmium/


Cadmium Compounds: http://www3.epa.gov/airtoxics/hlthef/cadmium.html