LEAD





Lead 3320
Photo by: Dreef

Lead

Overview

Lead is the heaviest member of the carbon family. The carbon family consists of the five elements in Group 14 (IVA) of the periodic table. The periodic table is a chart that shows how chemical elements are related to each other. Although a member of the carbon family, lead looks and behaves very differently from carbon.

Lead is one of only a few elements known to ancient peoples. One of the oldest examples of lead is a small statue found in Egypt. It was made during the First Dynasty, in about 3400 B.C. Mention of lead and lead objects can also be found in very old writing from India. And the Bible mentions lead in a number of passages.

SYMBOL
Pb

ATOMIC NUMBER
82

ATOMIC MASS
207.2

FAMILY
Group 14 (IVA)
Carbon

PRONUNCIATION
LED

Throughout history, Lead has been used to make water and sewer pipes; roofing; cable coverings; type metal and other alloys; paints; wrappings for food, tobacco, and other products; and as an additive in gasoline. Since the 1960s, however, there has been a growing concern about the health effects of lead. For instance, scientists have found that lead can cause mental and physical problems in growing children. As a result, many common lead products are now being phased out.

Discovery and naming

Lead has been around for thousands of years. It is impossible to say when humans first discovered the element. It does not occur as an element in the earth very often. But one of its ores, lead sulfide (PbS), is fairly common. It is not difficult to obtain pure lead metal from lead sulfide. Humans probably discovered methods for doing so thousands of years ago.

By Roman times, lead metal was widely used. The far-reaching system that brought water to Rome contained many lead pipes. Sheets of lead were used as writing tablets and some Roman coins were also made of lead. Perhaps of greatest interest was the use of lead in making pots and pans. Modern scientists believe many Romans may have become ill and died because of this practice. Cooking liquids in lead utensils tends to make the lead dissolve. It got into the food being cooked. People who ate those foods got more and more lead into their bodies. Eventually, the effects of lead poisoning must have begun to appear.

Of course, the Romans had little understanding of the connection between lead and disease. They probably never realized that they were poisoning themselves by using lead pots and pans.

No one is quite sure how lead got its name. The word has been traced to manuscripts that date to before the 12th century. Romans called the metal plumbum. It is from this name that the element's chemical symbol comes: Pb. Compounds of lead are sometimes called by this old name, such as plumbous chloride.

Physical properties

Lead is a heavy, soft, gray solid. It is both ductile and malleable. Ductile means capable of being drawn into thin wires. Malleable means capable of being hammered into thin sheets. It has a shiny surface when first cut, but it slowly tarnishes (rusts) and becomes dull. Lead is easily worked. "Working" a metal means bending, cutting, shaping, pulling, and otherwise changing the shape of the metal.

The melting point of lead is 327.4°C (621.3°F), and its boiling point is 1,750 to 1,755°C (3,180 to 3,190°F). Its density is 11.34 grams per cubic centimeter. Lead does not conduct an electric current, sound, or vibrations very well.

Chemical properties

Lead is a moderately active metal. It dissolves slowly in water and in most cold acids. It reacts more rapidly with hot acids. It does not react with oxygen in the air readily and does not burn.

Occurrence in nature

The abundance of lead in the Earth's crust is estimated to be between 13 and 20 parts per million. It ranks in the upper third among the elements in terms of its abundance.

Lead rarely occurs as a pure element in the earth. Its most common ore is galena, or lead sulfide (PbS). Other ores of Lead are anglesite, or lead sulfate (PbSO 4 ); cerussite, or lead carbonate (PbCO 3 ); and mimetite (PbCL 2 ○ Pb 3 (AsO 4 ) 2 ).

The largest producers of lead ore in the world are Australia, China, the United States, Peru, Canada, Mexico, and Sweden. In the United States, more than 93 percent of all the lead produced comes from Missouri. Other lead-producing states are Montana, Colorado, Idaho, Illinois, New York, and Tennessee. In 1996, 426,000 metric tons of lead were produced in the United States.

Isotopes

Four naturally occurring isotopes of lead occur. They are lead-204, lead-206, lead-207, and lead-208. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope.

About sixteen radioactive isotopes of lead are known also. A radioactive isotope is one that breaks apart and gives off some form of radiation. Radioactive isotopes are produced when very small particles are fired at atoms. These particles stick in the atoms and make them radioactive.

Romans routinely ate food cooked in lead pots and pans. The connection between lead and disease was not known then, so many people became ill and died of lead poisoning.

One radioactive isotope of lead, lead-210, is sometimes used in medicine. This isotope gives off radiation that can kill cancer cells. It is also used to treat non-cancerous eye disorders.

Lead smelting.
Lead smelting.

Extraction

Lead is obtained from its ores by a method used with many metals. First, the ore is roasted (heated in air). Roasting, also called smelting, converts the ore to a compound of lead and oxygen, lead oxide (PbO 2 ). Lead oxide is then heated with charcoal (pure carbon). The carbon takes oxygen away from the lead oxide. It leaves pure lead behind:

Lead obtained in this way is not very pure. It can be purified electrolytically. Electrolytic refining involves passing an electric current through a compound. Very pure lead is collected at one side of the container in which the reaction is carried out.

A major source of lead is recycled car batteries.

Lead is also recovered in recycling programs. Recycling is the process by which a material is retrieved from a product that is no longer used. For example, old car batteries were once just thrown away. Now they are sent to recycling plants where lead can be extracted and used over and over again. It is not necessary to get all the lead that industry needs from new sources, such as ores.

Uses

The lead industry is undergoing dramatic change. Many products once made with lead no longer use the element. The purpose of this change is to reduce the amount of lead that gets into the environment. Examples of such products include ammunition, such as shot and bullets; sheet lead used in building construction; solder; water and sewer pipes; ball bearings; radiation shielding; and gasoline. These changes are possible because manufacturers are finding safer elements to use in place of lead.

The price of a gallon of gas

F or many years, lead was regarded as a miracle chemical by the automotive industry. The power to run a car comes from the burning of gasoline in the engine. However, burning gasoline is not a simple process. Many things happen inside an engine when gasoline burns in the carburetor.

For example, an engine can "knock" if the gasoline does not burn properly. "Knocking" is a "bang-bang" sound from the engine. It occurs when low-grade gasoline is used.

One way to prevent knocking is to use high-grade gasoline. Another way is to add chemicals to the gasoline. The best gasoline additive discovered was a compound called tetraethyl lead (Pb(C 2 H 5 ) 4 ). Tetraethyl lead was usually called "lead" by the automotive industry, the consumer, and advertisers. When someone bought "leaded" gasoline, it contained not lead metal, but tetraethyl lead.

Leaded gasoline was a great discovery. It could be made fairly cheaply and it prevented car engines from knocking. No wonder people thought it was a miracle chemical.

What people didn't realize was that tetraethyl lead breaks down in a car engine because of the high temperature at which engines operate. When tetraethyl lead breaks down, elemental lead (Pb) is formed:

The result—with millions of cars being driven every day—was more and more lead getting into the air. And more and more people inhaled that lead. Eventually, doctors began to see more people with leadrelated diseases.

The federal government finally decided that tetraethyl lead was too dangerous to use in gasoline. By 1990, the use of this compound had been banned by all governments in North America.

Other uses of lead have not declined. The best example is lead storage batteries. A lead storage battery is a device for converting chemical energy into electrical energy. Almost every car and truck has at least one lead storage battery. But no satisfactory substitute for it has been found. About 87 percent of all lead produced in the United States now goes to the manufacture of lead storage batteries. In addition to cars and trucks, these batteries are used for communication networks and emergency power supplies in hospitals, and in forklifts, airline ground equipment, and mining vehicles.

Compounds

A small percentage of lead is used to make lead compounds. Although the amount of lead is small, the variety of uses for these compounds is large. Some examples of important lead compounds are:

lead acetate (Pb(C 2 H 3 O 2 ) 2 ): insecticides; waterproofing; varnishes; dyeing of cloth; production of gold; hair dye

lead antimonate (Pb 3 (SbO 4 ) 2 ): staining of glass, porcelain and other ceramics

lead azide (Pb(N 3 ) 2 ): used as a "primer" for high explosives

lead chromate ("chrome yellow"; PbCrO 4 ): industrial paints (use restricted by law)

lead fluoride (PbF 2 ): used to make lasers; specialized optical glasses

lead iodide (PbI 2 ): photography; cloud seeding to produce rain

lead naphthenate (Pb(C 7 H 12 O 2 )): wood preservative; insecticide; additive for lubricating oil; paint and varnish drier

lead phosphite (2PbO ○ PbHPO 3 ): used to screen out ultraviolet radiation in plastics and paints

lead stearate (Pb(C 18 H 35 O 2 ) 2 ): used to make soaps, greases, waxes, and paints; lubricant; drier for paints and varnishes

lead telluride (PbTe): used to make semiconductors, photoconductors, and other electronic equipment

Health effects

The health effects of lead have become much better understood since the middle of the 20th century. At one time, the metal was regarded as quite safe to use for most applications. Now lead is known to cause both immediate and long-term health problems, especially with children. It is toxic when swallowed, eaten, or inhaled.

Young children are most at risk from lead poisoning. Some children have a condition known as pica. They have an abnormal desire to eat materials like dirt, paper, and chalk. Children with pica sometimes eat paint chips off walls. At one time, many interior house paints were made with lead compounds. Thus, crawling babies or children with pica ran the risk of eating large amounts of lead and being poisoned.

Some symptoms of lead poisoning include nausea, vomiting, extreme tiredness, high blood pressure, and convulsions (spasms). Over a long period of time, these children often suffer brain damage. They lose the ability to carry out normal mental functions.

Other forms of lead poisoning can also occur. For example, people who work in factories where lead is used can inhale lead fumes. The amount of fumes inhaled at any one time may be small. But over months or years, the lead in a person's body can build up. This kind of lead poisoning can lead to nerve damage and problems with the gastrointestinal system (stomach and intestines).

Lead causes both immediate and longterm health problems, especially with children. It is toxic when swallowed, eaten, or inhaled.

Today, there is an effort to reduce the use of lead in consumer products. For instance, older homes are often tested for lead paint before they are resold. Lead paint has also been removed from older school buildings.



User Contributions:

Demi-Jessica
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Nov 6, 2007 @ 6:18 pm
I am going to make sure that I let the kids in my chemistry class know about this site. This will help them with their projects also.

thanks again,

Demi-Jessica
vede
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Mar 5, 2008 @ 7:07 am
THANK YOU IT WAS VERY USEFULL.i will request my friends also to watch the site
Jaaiz
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Mar 7, 2008 @ 2:14 pm
THANKS ALOT.This website is very useful for me.I needed some information concern with my school projet.And I got lots of information from here.Greate!!!!!
Thanks again
R.D.Lokhande
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May 6, 2008 @ 7:07 am
It is an eye opening. We just thought that the asbestos is only dangerous to the environment. Considering the increase in volume of lead usage in different forms I feel one day this will also will cause of concern and then it will be out of control. Incidently I would like to share my experience about famous lake of Nainital in India which has lead concentartion alarmingly and now it has become concern and there is no good solution to get away with it.

LOKHANDE
potato
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Feb 25, 2009 @ 9:21 pm
This is a very good site. I recommend this site for
for reports. This is the best site about lead I have ever seen. I didn't regret going on this site.:-)
Katie
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Oct 7, 2009 @ 1:01 am
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Thanks, it helped me a lot on my school asiment
Smart-Attack
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Oct 8, 2009 @ 7:19 pm
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pufferpaint
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Jan 9, 2010 @ 3:15 pm
wow.. absolutly love this site help me so much! :)
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Mar 9, 2010 @ 7:07 am
Very good website. Does anyone have a reference for natural levels of lead in the uk?
Iryna
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Mar 24, 2010 @ 10:22 pm
wow.. awsome!!! This really helped a lot:D thanks!!!
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Apr 6, 2010 @ 3:15 pm
thank you so so much the info you provided has been
so useful for a paper i have due today :)
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Jun 29, 2010 @ 5:05 am
GOOD KEEP THE SITE LIKE THIS FOREVER. IS THERE ANY OTHER ELEMENTS LIST IN YOUR SITE? PLEASE PROVIDE ME THE ADDRESS.
joab njagi
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Aug 25, 2010 @ 2:02 am
congrats to all the contributors to make this website a success. It really saved me a lot of trouble. Keep it up.
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Sep 10, 2010 @ 3:15 pm
this website was very usefull it helped me with my science project
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Nov 1, 2010 @ 5:17 pm
I'm not sure you have it quite correct about the Romans. They certainly knew that miners and refiners of lead became sick and died and that this was related to working with lead. Pity the self-poisoning of the rich was slow enough for them not to link the two.
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Nov 23, 2010 @ 9:09 am
This was very useful this website got everything i was researching for.
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Feb 6, 2011 @ 11:11 am
Thank you so much I purchase a wallet made with lead, I"m going to return it thanks again..
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Apr 19, 2011 @ 9:21 pm
what is the chemical used to check for lead in paint. thanks, milan
Meilin Gutierrez
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May 11, 2011 @ 10:10 am
this site is awesome it helped me on my school assingnment in science
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May 17, 2011 @ 2:14 pm
thank you very much i couldnt do my science project with ut this information
allison,..
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Sep 22, 2011 @ 1:13 pm
Thankkss! I havee a paper duee! This helped alott!!!(:
Crystal
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Sep 22, 2011 @ 5:17 pm
Good! And easy to understand for me as an international student, I am not worrying about my project anymore
Leslie
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Sep 29, 2011 @ 8:08 am
This really helped me on my chemistry paper.. Thank you
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Oct 6, 2011 @ 6:18 pm
thank u very much this helped me a lot wit mi science project
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Oct 7, 2011 @ 9:09 am
this helped me TONS with my chemistry assignment ! Thanks alot ! :)
lexis
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Oct 16, 2011 @ 4:16 pm
Thank you soo much, this site was incredibly useful to me, now i know everything i need to know for my chemistry project :)
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Oct 19, 2011 @ 7:19 pm
very good article but can u put more articles but of specifically of chemistry of batteries please but thank u this article really help me with my proyect
Alice
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Nov 2, 2011 @ 5:17 pm
OMG THIS WEBSITE REALLY HELPED ME!! IT GAVE ME LIKE EVERYTHING I NEEDED FOR MY PROJECT!! THANK YOU!! :D
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Nov 8, 2011 @ 8:20 pm
WOW. Useful website! Thank you! Keep it up please!
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Nov 18, 2011 @ 5:05 am
This site is amazing, I got so much information for my essay about lead!
Lead
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Dec 6, 2011 @ 4:16 pm
How was named?
Uses of the element?
What was the Properties?
What is the Period?
Who Discovery
When it was Discovery?
Where it was Discovery?
Other intersting fact???(color,odor,whether it's dangerous-explosive,radioactive,etc)


P.S Thank You for your help.
I Doing a Chemical Elements Project
Jacob
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Jan 10, 2012 @ 8:08 am
thanks i had a big powerpoint to due to day and i wounld not have got it done with out ur guys help thanks
Josh
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May 17, 2012 @ 12:12 pm
Wonderful amount of information. I am using this for one of my biggest junior projects, and this just about hit our topic of lead pollution and poisoning right on the head. Very informational and easy to understand.
SWEETNESS
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Oct 17, 2012 @ 6:18 pm
Thanks for the awsome element info. This webite is awsome no matter what other people say. It really helps me out when i'm doing my HW.Peace, love, happyness,and this page. Peace out!
Bob
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Nov 7, 2012 @ 3:15 pm
Great Website !! Helped me tremendously with my powerpoint presentation.
jeremy
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Nov 8, 2012 @ 9:21 pm
dang, thannks guys big project do tomorrow due tomorrow haha last minut shit lol thanks
Paige
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Nov 9, 2012 @ 1:13 pm
Thank you so much. I have to do a science project. But I all I need is 5 facts about lead.
cameron
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Nov 28, 2012 @ 11:11 am
thanks im doing a poster an lead the element from the periodic table lol heloped a lot cheers hahahah :)
jamie
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Dec 8, 2012 @ 1:13 pm
THANK YOU I AM DOING A PROJECT ON THE ELEMENT LEAD
christian
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Dec 13, 2012 @ 1:13 pm
this is a good site to find all about lead, but it missing 1 more thing. what is the hyphen notation of the most abundant isotope of lead.
Ariel
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Jan 3, 2013 @ 5:17 pm
Alright!!! Now that I've found my source of information I can tell my friends about it. I can also finish my big power point that's due next week. Thanks for the help.
Zaw
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Apr 3, 2013 @ 11:11 am
How to produce Galena ore to pure lead in small industry?
kyle
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Apr 4, 2013 @ 9:09 am
it helped so much I graciously thank every
one who contributed god bless you all but not the queers
Eliza
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Jun 3, 2013 @ 1:13 pm
Very good site for students to learn and do their projects.
Vrukshi
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Jun 8, 2013 @ 9:09 am
It is a amazing site for children. It helped me a lot in my chemistry project.
zhin
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Jun 11, 2013 @ 3:03 am
I want to know about lead poison (Lead and its human effects) and Lead poisoning can cause anemia
Bill
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Aug 12, 2013 @ 2:02 am
This a realy cool website. It really helped keep it going!
Ben
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Oct 21, 2013 @ 11:11 am
Great information, applicable to many areas of interest however would appreciate any information on How could Source this information?
Cassy
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Dec 27, 2013 @ 1:13 pm
OMG THANK YOU SO MUCH. This website helped me so much on my chemistry project. It had literally all the information I needed. I will def show this website to all of my friends.
Anirudh
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Feb 21, 2014 @ 9:21 pm
OMG THANK YOU SO MUCH. This website helped me so much on my chemistry project. It had literally all the information I needed. I will def show this website to all of my friends.
Wizzard
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Aug 27, 2014 @ 1:13 pm
A correction is needed. Gasoline is not burnt (or combusted) in the carburetor.

Thank you.

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