Lead:
I chose to write my metal report on lead. Lead, or Pb on the periodic table, is an extremely toxic element-- a heavy metal. Lead has 82 protons, 82 electrons, and an atomic mass of 207; this indicates that when neutralized, lead has 125 neutrons. As an ion, lead has a positive 2 charge. Lead also has four stable isotopes, 204Pb, 206Pb, 207Pb, and 208Pb; All except for lead-204 can be found in the end products of the radioactive decay of uranium and thorium. Since the toxicity of lead is so serious and can be fatal, since 1978, it usage has been significantly reduced. Occasionally, lead and lead compounds are still used in pottery, electrical storage batteries, solder, cooking vessels, pesticides, and paints. It is still used to paint bridges and other steel structures with paint made with red lead (Pb3O4), a compound of lead and oxygen. Because of its relatively low reactivity (not quite as low as gold or silver), it protects these steel structures from corrosion. This however, is not a threat to the general public, but if used in items that come in contact with humans, will cause lead poisoning that can result in death. Interestingly enough, lead's symbol, Pb, comes from the Latin name plumbum, the basis of the word plumber and plumbing. This is because the water pipes in ancient Rome were made of lead. The Romans also used molten lead to secure iron pins that held huge limestone blocks in buildings together. In the early 1800s, water pipes in the US were also made of lead, but, due to poisoning, were replaced by iron, then copper and plastic. Lead was also used in the US in the paint used on homes built before 1978. Many children would become very sick, especially toddlers, from coming in contact with the flaking paint. Lead-based paint is no longer used in homes; alternatives like water-based paints are used instead. Dangerous contamination in soil remains today due to the tetraethyl lead, Pb(C2H5)4 added to gasoline before 1970, and consequently released into the atmosphere through automobile exhaust as lead oxide, the oxidized, and therefore heavier form of lead. Furthermore, since lead is so heavy, especially oxidized, it is used to protect from radiation from x-rays and to make weights, such as fishing weights. Since there are less regulations in countries like China, lead is still commonly used to produce items. In fact, the US has been affected by toys made with lead paint imported from China. Children were made sick and even faced death from simply playing with barbies, action figures, and building kits. An example of this is the March 2006 recall of Mega Brands Inc. Mega Brans Inc. recalled 3.8 million Magnetix magnetic building sets after four children became extremely ill and one child died after swallowing tiny magnets included in the set. To illustrate the severity of these recalls and the effects they have on companies, after a Fisher-Price recall where Chinese officials had to ban the toys' manufacturer, from exporting products, a co-owner of the company committed suicide at a warehouse over the weekend by hanging himself. It is important to recognize that lead is not only found in less regulated countries, but all over the world. In fact, car batteries are usually made out of significant amounts of lead! Surprisingly enough, the chief producers of lead, or where it is chiefly mined, is, from greatest to least, The US, China, Germany, the United Kingdom, and Japan. Lead is highly abundant, quite unreactive, and found in the lithosphere of earth. Sometimes it is found uncombined, but usually it is found in ore with zinc, silver, and copper. Lead is extracted from these ores using pyrometallurgy, the treatment of the metals and their ores with heat, as in a blast furnace-- the common reducing agents being Carbon (coke) and carbon monoxide.
Lead is a heavy metal, so most lead poisoning comes from low levels of exposure for an extended period of time; therefore, lead poisoning usually causes symptoms when the level in blood has become very high. Heavy metal poisoning damages the nervous system, the brain, the kidneys, the liver, and can lead to death.
Physical symptoms in children and adults when lead poisoning levels are severe:
-Stomachaches, cramping, constipation, or diarrhea
-Nausea, vomiting
-Persistent, unexplained fatigue
-Headache
-Muscle weakness
Severe symptoms from uncommonly high exposures to lead:
-Seizures
-Unconsciousness
-Paralysis
-Brain swelling
Behavioral indications of low-moderate blood lead levels, not obvious symptoms of lead poisoning:
*Children:
-Irritability or aggressiveness
-Hyperactivity, being easily distracted, impulsiveness
-Learning problems
-Lack of interest in play
-Loss of appetite
-Smaller than other children
*Adults:
-Irritability
-Unexplained changes in mood or personality
-Changes in sleep patterns
-Inability to concentrate
-Memory loss
Neurological symptoms: effects of lead on the nervous system:
-Poor coordination
-Weakness in hands and feet
-Headaches
-Seizures
-Paralysis
-Coma
Works cited: (main sources):
http://en.wikipedia.org/wiki/Lead#History
http://en.wikipedia.org/wiki/Lead#Characteristics
http://en.wikipedia.org/wiki/Isotopes_of_lead
http://en.wikipedia.org/wiki/List_of_alloys#Alloys_of_lead
http://www.msnbc.msn.com/id/20254745/ns/business-consumer_news/t/mattel-issues-new-massive-china-toy-recall/
http://children.webmd.com/tc/lead-poisoning-symptoms
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