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Dr. Mahes Kundagol

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 A metal  is a chemical element that is a good conductor of both electricity and heat and forms cations and ionic bonds with non-metals.

 A metal  is an element, compound, or alloy

characterized by high electrical conductivity. In a metal, atoms readily lose electrons to form positive

ions (cations). Those ions are surrounded bydelocalized electrons, which are responsible for the

conductivity. The solid thus produced is held byelectrostatic interactions between the ions and theelectron cloud, which are called metallic bonds

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 An element whose atoms are packed closely together by strong forces of attraction with freeelectrons moving around

Physical Properties:- Good conductor of electricity - High melting point- High thermal conductivity 

- High density - Malleable- Ductile

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Element  Percent by mass  Atomic percent (calc.) Oxygen  65%  25.6% Carbon  18%  9.5% Hydrogen  10%  63% Nitrogen  3%  1.3% Calcium  1.5%  0.24% Phosphorus  1.2%  0.24% Potassium  0.2%  0.03% Sulfur  0.2%  0.04% Chlorine  0.70%  0.04% Sodium  0.1%  0.03% Magnesium  0.05%  0.01% Iron  3 g in men, 2.3 g in women Cobalt, Copper, Zinc, Iodine  < 0.05% each 

Selenium, Fluorine  < 0.01% each 

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Other elements necessary for human life are-

Manganese

Molybdenum

Nickel  A small amount of chromium is necessary for proper

health.

Boron has been found necessary for optimal health inrats, so presumably it plays a role in humans as well.

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The elements needed for life are relatively common in theEarth's crust, and conversely most of the common elementsare necessary for life.

 An exception is aluminium, which is the third most commonelement in the Earth's crust (after oxygen and silicon), but

seems to serve no function in living cells. Rather, it isharmful in large amounts.

Besides these elements that are necessary for life, our bodiescontain trace quantities of most other elements, including

some that are harmful, such as mercury, cadmium, and lead.

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The heavy metal refers to any metallic chemical element that has a

relatively high density and Is toxic or poisoness at low concentrations

.Examples of heavy metals include (Hg),cadmium(Cd).,Arsenic (As),

chromium(Cr) Thallium(TL) and Lead(PB).

 Heav metals are natural components of the Earth's crust. They cannot be

degraded or destroyed. To a small extent they enter our bodies via food,

drinking water and air as trace element 

essentialto maintain the metabolism oflhe human body.However,et 

hlghermncentrallans IIley Olin lead to pglaan!ng. Heavy metalpoisoningmu!c:t result,fOr instanCII,fromdrinking-watermntaminaticn (a.g.lead 

 pipes),high ambient air c:oncentratians near emission sourceso, rintake via

thefOod dlain.

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