Lead Definition and 292 Threads

Lead is a chemical element with the symbol Pb (from the Latin plumbum) and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and also has a relatively low melting point. When freshly cut, lead is silvery with a hint of blue; it tarnishes to a dull gray color when exposed to air. Lead has the highest atomic number of any stable element and three of its isotopes are endpoints of major nuclear decay chains of heavier elements.
Lead is a relatively unreactive post-transition metal. Its weak metallic character is illustrated by its amphoteric nature; lead and lead oxides react with acids and bases, and it tends to form covalent bonds. Compounds of lead are usually found in the +2 oxidation state rather than the +4 state common with lighter members of the carbon group. Exceptions are mostly limited to organolead compounds. Like the lighter members of the group, lead tends to bond with itself; it can form chains and polyhedral structures.
Lead is easily extracted from its ores; prehistoric people in Western Asia knew of it. Galena is a principal ore of lead which often bears silver. Interest in silver helped initiate widespread extraction and use of lead in ancient Rome. Lead production declined after the fall of Rome and did not reach comparable levels until the Industrial Revolution. In 2014, the annual global production of lead was about ten million tonnes, over half of which was from recycling. Lead's high density, low melting point, ductility and relative inertness to oxidation make it useful. These properties, combined with its relative abundance and low cost, resulted in its extensive use in construction, plumbing, batteries, bullets and shot, weights, solders, pewters, fusible alloys, white paints, leaded gasoline, and radiation shielding.
In the late 19th century, lead's toxicity was recognized, and its use has since been phased out of many applications. However, many countries still allow the sale of products that expose humans to lead, including some types of paints and bullets. Lead is a neurotoxin that accumulates in soft tissues and bones; it damages the nervous system and interferes with the function of biological enzymes, causing neurological disorders, such as brain damage and behavioral problems.

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  1. John Covert

    Is lead salvaged from hospital x-ray shielding safe?

    I am a lay person, so the physics lesson would only confuse me. I do reloading of ammunition for competitive shooting (Cowboy Action Shooting). I have someone offering to sell lead for melting and casting bullets. He has indicated its source was shielding from hospitals used in X-ray shielding...
  2. Z

    I The Mandela Effect: Possible lead?

    Hello, I would like to start by saying I'm not sure if this is the right forum for this, I created an account here today after positing to a friend of mine a random thought I had. I was enjoying a video on YouTube about the Berenstain Bears theory, that claims a large amount of people who are...
  3. wolram

    Lead-Free Soldering: Is My 60W Iron Enough?

    I am try to build a radio and find i just can not use the lead less solder, I have a 60 watt iron and the solder takes ages to melt and i get a lot of splatter, Is my iron powerful enough? I used to be very good with the lead solder.
  4. M

    I Does global topology lead to a preferred frame in SR?

    According to this author, http://www.math.uic.edu/undergraduate/mathclub/talks/Weeks_AMM2001.pdf, a locally Minkowski spacetime with a nontrivial global topology may have a preferred inertial frame, in the sense that hypersurfaces of constant time can only be defined using particular time...
  5. I

    B How does a Bell State lead to a probability in the CHSH game

    Hi, I am a student in the Netherlands, and I'll be attending university next year. However, I am doing some form of research on Quantum Computing with another student for our so-called "profielwerkstuk" but my understanding of Quantum Physics and math is sometimes not at the level that is...
  6. M

    Programs SULI Argonne Internship - Things It Can Lead To

    Hi there PF, Say I get into SULI at Argonne (a current researcher there wants me to be in their group next summer and says it'll be pretty likely I'll get in). The work I do will of course be important, but does the brand name mean anything (to grad schools, employers like Intel/IBM, etc)...
  7. K

    Why does this system of equations lead to inaccurate results?

    Homework Statement A soccer ball is kicked. If there is a 3 meter high fence, that is 6 meters away, compute the angle of the kick and the magnitude of the velocity of a ball. Homework Equations a_y=-g v_y=-gt+v_y_0 s_y=-(1/2)gt^2+v_y_0(t) v_x is constant: we neglect air resistance. 6=v_x_0t...
  8. K

    Atom Volume Calc: Find the Volume of a Lead Atom

    Homework Statement Lead has a mass of 11.35 g per cubic centimeter of volume, and the mass of one of its atoms is 3.439×10-25 kg. If the atoms are spherical and tightly packed, what is the volume of an individual atom? ( m3) Homework Equations conversions The Attempt at a Solution For this...
  9. Priyadarshini

    Savant Syndrome: How Does Damage to the Brain Lead to Such Ability?

    Wikipedia states that "Savant syndrome results from damage to the left anterior temporal lobe, an area of the brain key in processing sensory input, recognizing objects and forming visual memories.", but if the area of the brain which processes sensory input get damaged how does the syndrome...
  10. victorhugo

    I What lead N.Bohr to come up with his postulates?

    I can find information everywhere about his postulates but not how he came up with them either than the hydrogen spectrum.
  11. C

    Time of collision of two lead spheres

    Homework Statement Two uniform lead spheres each have mass 5000kg and radius 47cm. They are released from rest with their centres 1m apart and move under their mutual gravitational attraction. Show that they will collide in less than 425s. Homework Equations By Gauss' Law, force on a sphere...
  12. EBPoncho

    PET/CT Gamma Ray Protection with Lead Apron

    I was informed I might get a better response by posting to this forum, so sorry for the double post. Hello all, I am currently attending a service course for a PET/CT system for my employer. We have been covering the physics behind the function of detectors and my instructor said something...
  13. LoveQM

    I How did Einstein see that Entanglement lead to Connectedness

    I am studying the history of Quantum Mechanics and was reading about particle entanglement. What I would like to know is how did Einstein see that particle Entanglement meant that particles would be affected by spooky action at a distance. I guess that spooky action at a distance may also be...
  14. Kara386

    Lead is compressed reversibly with T const, find dS

    Homework Statement Lead is compressed reversibly and with temperature kept constant at 300K, and from pressure of 1bar to 1000 bar. Assuming the change in volume is small, what is the change in entropy S? Use the Maxwell relation derived from Gibbs free energy function. V = ##10^{-3}m^3##...
  15. R

    Lead Screw diameter for lifting 200Kgs

    Hi I one of my application i am using the lead screw arrangement to lift 200kg weight using handle I used trapezoidal thread and nut. Could anybody suggest the diameter required for lifting the weight of 200kg
  16. Erenjaeger

    Ice melted by impact of lead bullet

    Homework Statement A 3.20 g lead bullet at 28.0°C is fired at a speed of 210 m/s into a large block of ice at 0°C, in which it becomes embedded. What mass of ice melts (g)? Homework Equations I thought that the KE of the bullet would be transferred into heatThe Attempt at a Solution I used...
  17. TheSodesa

    Precipitation of lead hydroxide in the presence of EDTA

    Homework Statement 1. The question EthyleneDiamineTetra-acetate(##EDTA^{4-}##) is used in chemical analysis as a complex-former. ##EDTA^{4-}## is also used to treat heavy metal poisoning, as it forms water soluble complexes with them which can then be easily removed by the body. The reaction...
  18. SadPanda6022

    Density floating problem, wood and lead

    1. Homework Statement A block of wood has a mass of 3.47 kg and a density of 628 kg/m3. It is to be loaded with lead (1.13 × 104 kg/m3) so that it will float in water with 0.848 of its volume submerged. What mass of lead is needed if the lead is attached to (a) the top of the wood and (b) the...
  19. H

    I Does the Universe's Expansion lead to Critical Mass < 1?

    We understand that for the Universe to be flat, the critical mass of everything that has mass must total an omega of 1.0. At first, with our lack of knowledge regarding dark energy, we thought that the universe that we detected (ordinary matter and dark matter) did not even add up to a third of...
  20. kyphysics

    News Good Lord, Lead Poisoning in Other Parts of Michigan Too

    https://www.yahoo.com/health/lead-poisoning-other-parts-michigan-222900551.html First, I actually lived in Michigan for 3.5 years (in Ann Arbor, Jackson and Ypsilanti), so I wonder if I could have been affected! Secondly, does lead poisoning only affect children? No teens/YA to full adults...
  21. S

    Can a Supercapacitor be Charged with Only One Wire and a Grounded Battery?

    Why can't I charge my supercapacitor with 1 wire? If the ions in the electrolyte make up the opposite electroldes, why won't it store charge when I charge it with 1 wire? It makes since for it to hold less charge but it's not charging at all. I'm using a grounded battery. 1 wire to my...
  22. A

    Effect of Phase Lead Compensator on Phase and Gain margins

    Homework Statement What is the effect on the phase and gain margins of a system when a Phase Lead Controller/Compensator is added? Homework Equations I have designed the phase lead controller for the system so if anyone wants to see it, please ask The Attempt at a Solution I know, that in...
  23. A

    Effect of Phase Lead Compensator on Phase and Gain margins

    Homework Statement I was just wondering what was the general effect on phase and gain margins when a phase lead compensator was is added to a system. Homework EquationsThe Attempt at a Solution
  24. N

    Engineering Will biomedicine lead to master of biomedical engineering?

    i'm currently enrolled in a degree in biomedicine, i want to know whether i can do a master in bio medical engineering , the employability of the field and what sort of content is there in such a degree ?
  25. A

    Can Reverse Polarity Charging Convert Old Lead Acid Batteries into Pure Pb?

    Hello, according to the lead acid battery standard equations The overall chemical reaction is: At the negative terminal the charge and discharge reactions are: At the positive terminal the charge and discharge reactions are: My Q? If we empty all liquid from old battery and add H2O...
  26. newjerseyrunner

    Could Dark Energy lead to a big bang?

    I had a thought a while ago, but it was removed because I cited a youtube video of physicists talking rather than papers, so I'll have another go. My thought was that the universe could be cyclical and infinite even if heat death is the eventual end of the universe as we know it. During the...
  27. M

    Standard entropy of liquid lead at 500C?

    Homework Statement The standard entropy of lead at 25C is S(298)=64.80 J/Kmol. The heat capacity of solid lead is Cp(s) = 22.13 + .01172T + 0.96x105T-2. The heat capacity of liquid lead is Cp(l) = 32.51 - 0.00301T Melting point is 327.4C Heat of fusion is 4770J/mol. Calculate the standard...
  28. A

    How redshift/brightness lead to acceleration/deceleration?

    I have read several articles about this topic, on Wikipedia but for example also this article http://supernova.lbl.gov/PDFs/PhysicsTodayArticle.pdf and also several books that discuss the subject. In very brief my understanding is that: - 1. When observing type 1a supernovae (standard candle) at...
  29. Oribe Yasuna

    Radius of a lead nucleus and alpha particle

    Homework Statement A lead nucleus contains 207 nucleons (82 protons and 125 neutrons) packed tightly against each other. A single nucleon (proton or neutron) has a radius of about 1 ✕ 10^−15 m. (a) Calculate the approximate radius of the lead nucleus. (b) Calculate the approximate radius of...
  30. M

    Show that rotations and boosts lead to a combined boost

    Homework Statement Prove that applying an infinitesimal rotation of angle k<<1 around the axis x1, then a boost of speed -k along the axis x2 then the inverses of these is equal to a single boost of speed k^2 along the axis x3 The Attempt at a Solution Putting this into mathematical terms I...
  31. astrophysicskid

    Exploring Wormholes: Where Do They Lead?

    I don't know pretty much about worm holes. but I have this doubt. Where do worm holes lead us to if we get into one?Do they lead us to a new but different universe or into some other part of this universe?
  32. J

    Lead pellet shot vertically into a clay block

    Homework Statement Homework Equations PCM ∑pi=∑pf v2=u2+2asThe Attempt at a Solution First, using the PCM equation, I found the final velocity of the block, which is about 10.5 ms-1. Then by using the SUVAT formula, i would be able to find the distance moved by the block, but I don't have...
  33. N

    How does band structure lead to metals/insulators?

    I almost "get" it, but not quite. Can someone help? Here is my current understanding. Say you solve the Kronig-Penny model. You find that you get bands of N closely spaced energy levels, with large gaps between them. Under normal conditions, electrons fill the band to some level (let's say we...
  34. N

    Linear force on lead screw drive

    I have a lead screw drive. The stepper motor puts out 280 oz-in of torque. Its attached to a 1/2 inch dia., .200" pitch, 2 start lead screw. There is a plate that's attached to the screw that moves back and forth along the screw. How much force can that metal plate exert in a linear motion?
  35. Dr Transport

    Classical Long lead time in getting text books

    Finally, got my new copy of Jackson's Classical Electrodynamics 3rd Ed. Took almost 40 days to come in from Amazon...Classmate said his copy won't be in until December. Is this becoming a trend??
  36. Stephanus

    Can kinetic energy lead to black hole?

    Dear PF Forum, I have a question in mind. But I'm not sure if this belong to SR forum, cosmology or classical physics. So I post it here. And perhaps as some of you might have known before or thought it over. It's about kinetic energy. Supposed this... A rocket, with a rest mass 1 ton. And the...
  37. Z

    Does exchange of identical particles lead to new state?

    Does an exchange of two identifical particles (electrons) lead to a new microscopic state?
  38. james gander

    Lead shielding against Van allen belts?

    (sorry - not sure about the prefix) I have read that lead shielding is dangerous against high energy particle radiation because of the high atomic number in lead. The particles would have high chance of hitting the lead atomic nuclei and producing x-rays. I am fed up with moon landing...
  39. I

    When do you begin to prove? which maths lead to proofs?

    Hi, Could someone please tell me at which point in learning maths do you begin to write and solve proofs? I have taken high school maths so far except for discrete math. If there is a list of different maths that lead up to proof writing, please let me know of them and in which order I...
  40. Z

    Lead compensator for double integrator

    I'm trying to design a lead compensator for a double integrator plant, which is plant = tf([1],[1 0 0]) I started with the angle condition. So, poles contribute (+) angle and zeros contribute (-) angle and that sums to 180 Desired pole location is 4.4 +- 4.4j So, 45 + 45 = 90 degrees comes...
  41. Y

    Self Locking in Worm Drive with lead angle of about 8

    Hi I have built a gear drive for robotic arm that uses a worm set (worm gear +worm) at stage one. Worm (wheel) is of bronze and worm gear is steel haing a lead angle of appx 8 deg. This set is further coupled to a spur gear set that further increases the torque such that the over all gear ratio...
  42. S

    The Effects of Radiation on Lead: Examining the Tsar Bomb

    I've read that the Tsar Bomb used a lead casing for the second and third stages of the bomb instead of a uranium casing. A uranium casing would have resulted in fast fusion but would have created too much fallout. Typical Hydrogen bombs use uranium casings. A uranium casing would have indeed...
  43. Marcis Rancans

    Parasitic capacitance influence on lead voltage

    V' changes over time. How can I determine the influence from parasitic capacitance (~50 pF) on V? R wire ~ 100 ohm. If I need to read data (V' can change rapidly) from this at 50hz, does it influence reading accuracy? How can I determine values from which I need to be careful when reading data...
  44. T

    Health concern about lead on components

    I know that for products produced in the EU and United States, I needn't worry about lead on components. That being said, I many times purchase products from Chinese sellers due to the low bulk price. I recently read that an electrical engineer with the tendency to chew wires while stripping...
  45. E

    I knowing what i'm looking for -- alpha particle colliding with lead nucleus

    Homework Statement An alpha particle with kinetic energy 15.0MeVmakes a collision with lead nucleus, but it is not "aimed" at the center of the lead nucleus, and has an initial nonzero angular momentum (with respect to the stationary lead nucleus) of magnitude L=p0b, where p0 is the magnitude...
  46. Robsta

    Lead's melting point as a function of pressure (Thermo')

    Homework Statement When lead is melted at atmospheric pressure, the melting point is 600K, the density decreases from 1.101x104 to 1.065x104 kgm-3. The latent heat is 24.5 kJ kg-1 Estimate the melting point of lead at a pressure of 100 atm. Homework Equations I haven't been able to find any...
  47. E

    Searching for any lead on realistic cord mechanics

    Hi all, I'm a physicist, and I'm now trying to understand and model a problem with a multishafted cord, being pulled from one side in order to transfer force. The cord has its own elastic properties (elongation, bending etc.), it goes through several pulleys with friction, and most likely its...
  48. R

    Grounding by touching a ground lead

    Is it possible to sufficiently ground yourself just by touching the negative lead of a wire coming from a power supply once?
  49. S

    Alpha Decay Half-Lives of Notable Light Isotopes: Estimates and Unknowns

    What is supposed to be the lifetime of lead against alpha decay? Notable light isotopes that DO undergo alpha decay: Be-8 188 keV 7*10ˇ-16 s Sm-146 2529 keV 103*10ˇ6 y U-235 4679 keV 704*10ˇ6 y U-238 4270 keV 4,47*10ˇ9 y Th-232 4083 keV 14,06*10ˇ9 y Sm-147 2310 keV 106,1*10ˇ9 y Pt-190 3252 keV...
  50. A

    Torque on lead screw based on psi

    So in a cnc machine, the screw that drives the x,y,z axiis are called "lead screws". I am constructing a machine that displences fluid at percise volumes. It will be essencially a seringe with one way valves coming in and going out. To open the "check valve" it requires at least 1.5 psi. If I am...
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