Metal vs Heavy Metal
Metals are known to human kind for a very long time. There are evidences to prove about metal usage back in 6000 BC. Gold and copper were the first metals to be discovered. These were used to make tools, jewelry, statues etc. Since then for a longer period only few other metals (17) were discovered. Now we are familiar with 86 different types of metals.
Metals are very important because of their unique characteristics. Usually metals are hard and strong (there are exceptions to this such as sodium. Sodium can be cut by a knife). Mercury is the metal which is in the liquid state. Besides mercury, all the other metals are found in the solid state, and it is hard to break them or change their shape compared to other nonmetal elements. Metals have a shiny appearance and most of them have a silvery shine (except gold and copper). Since some metals are very reactive with the atmospheric gases like oxygen, they tend to get dull colors over time. This is mainly due to the formation of metal oxide layers. On the other hand, metals like gold and platinum are very stable and unreactive. Metals are Malleable and ductile, which allows them to be used for making certain tools.
Metals are atoms, which can form cations by removing electrons. So they are electropositive. The type of bond forms between metal atoms is called metallic bonding. Metals release electrons in their outer shells and these electrons are dispersed between metal cations. Therefore, they are known as a sea of delocalized electrons. The electrostatic interactions between the electrons and cations are called metallic bonding. The electrons can move; therefore, metals have the ability to conduct electricity. Also, they are good thermal conductors. Because of the metallic bonding metals have an ordered structure. High melting points and boiling points of metals are also due to this strong metallic bonding.
Moreover, metals have a higher density than water. Elements in group IA and IIA are light metals. They have some variations from the above described general features of metal.
Heavy metals are elements in the periodic table which are metals or metalloids. There are about 23 heavy metals. These are transition metals, actinides, and lanthanides. Antimony, arsenic, bismuth, cadmium, cerium, chromium, cobalt, copper, gallium, gold, iron, lead, manganese, mercury, nickel, platinum, silver, tellurium, thallium, tin, uranium, vanadium, and zinc are the heavy metals that we know of. Heavy metals are specially known because of their toxicity. In our environment, small amounts of these elements are present.
It is necessary to have a certain amount of heavy metals in our diet and body in order to maintain a good health. However, large concentrations of heavy metal cause toxicity and it can cause a lot of damages to living organisms. For example, it can cause reduced mental activity or damage it. Further it can damage lungs, kidneys, liver and other important organs. Heavy metals can be accumulated in side living organisms over food chains. So it is important to know the sources of heavy metals and control their release to the natural environment.
What is the difference between Metal and Heavy Metal?
• Some of the metals are heavy metals.
• Heavy metals can be toxic when present in higher concentrations.
• Heavy metals are bio-accumulated compared to other metals.