What is Lead: Definition and 289 Discussions

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. hai_tep

    Lead hazard in Chinese crystals

    I want to use crystals from China for baby jewelry and it turns out that they use lead for the crystals - is there a risk of exposure through the skin to these crystals for babies
  2. Astronuc

    Margaret Hamilton, Lead Programmer, Apollo Program's Guidance Computer

    Margaret Hamilton the Pioneering Software Engineer Who Saved the Moon Landing https://interestingengineering.com/margaret-hamilton-software-engineer-who-saved-the-moon-landing Margaret Hamilton began working with Edward Lorenz, the father of Chaos Theory, in MIT's meteorology department. As...
  3. D

    I Black Hole to Other Universe: Violation of 1st Law?

    So I am a fan of astronomy, cosmology and astrophysics from a FAR. The math is way beyond my abilities but I like to just sometimes read and think about the very small parts I am able to comprehend. So my hats off to all of you that are able to fully enjoy this stuff, you're very lucky...
  4. M

    Calculate the torque needed to move a lead screw

    Summary:: Calculate the torque needed to move a load with a lead screw. Torque is needed in order to find the right DC motor and coupling. Hello, I have a design with using a lead screw to move a load (see sketch below). The load will operate in both directions, in order to select the right...
  5. jedishrfu

    How Slip Faults Lead to Massive Tsunamis

  6. Wrichik Basu

    COVID "High" dose of steroids in mild infection may lead to viral pneumonia?

    This is again based on what was said by the Director of AIIMS in a press conference. He said that many people are self-medicating, and taking high dose of steroids even in mild COVID infection, which increases viral multiplication and leads to viral pneumonia. From this new article, Two...
  7. T

    Why Does Second Collision in Ballistic Pendulum Lead to Initial State?

    I was thinking about ballistic pendulums and the symmetry they exhibit. In the simplest case, you have one ball that begins at a certain height and collides with another ball at rest. You can calculate via conservation of momentum and energy the new velocities and max vertical displacements...
  8. brotherbobby

    Sinking a toy boat with lead pellets

    Attempt : I begin by plotting the graph of depth x against mass of pellets m as shown alongside. Using ##m_B = \Delta m_L\Rightarrow m_B = \rho_L A_B\, x(B)## where ##\rho_L## is the density of the liquid, ##A_B## is the cross-sectional area of the boat and ##x(B)## is the depth to which the...
  9. I

    Considerations for design of lead screw + guide rail set up

    Hi everyone! I'm a mechanical engineering undergraduate and am designing a linear motion system for a school project. I hope to be able to use this system to achieve opposing motion for 2 x 200 kg loads (i.e. move them closer/ further apart simultaneously). Referring to the picture below...
  10. P

    Finding the excess electrons per lead atom

    a. This is easy with ## q = n*e ## ## 3.2 * 10^{-9} = n * 1.6*10^{-19} ## ## n = 2*10^{10} ## electrons b. Total Lead atoms are ## \frac {8 * 6.022*10^{23}} {207} = 2.3 *10^{22} ## I used the Avogadro number. Total electrons = ## 2.3 * 10^{22} * 82 = 1.88 * 10^{20} ##, here i multiplied with...
  11. B

    Lead screw's moment of inertia

    In order to choose a DC motor according to the article titled: APPYING MOTORS IN LINEAR MOTION APPLICATION by PITTMAN - step 4 : "determine the total reflected inertia (Jt) back from the load to lead screw shaft " . The formula is: Jt = Jscrew + Jload. This calculation relies on the fact...
  12. S

    B Symmetry in Higher Dimensions: Sean Carroll's Video & Physics

    I'm watching Sean Carroll's video on symmetry [relevant section at around 8:05] He talks about 120 degree rotations of triangles that leave them invariant. Then he proceeds to talk about flipping them with an interesting (at least to me) remark - "there's nothing that says I'm confined to...
  13. wrobel

    The Butterfly Effect: Small Changes Lead to Big Results

    Just an effect interesting to think about:
  14. R

    Mass spectrometer with a Lead element

    Summary:: How to load the plates with the Lead element in the spectrometer I have a mass spectrometer with lead element which has an electronic configuration 1s^2 2s^2 2p^6 3s^2 3p^6 3d^10 4s^2 4p^6 4d^10 5s^2 5p^6 4f^14 5d^10 6s^2 6p^2. It has 2 free electron, so the ejected electrons go...
  15. Elbow_Patches

    B Absorption of beta particles by lead

    Hello everyone, We conducted an experiment with a strontium-90 source and some different thicknesses of lead. With 2.1mm of lead the count rate (corrected for the background) was 0.69 counts per second, 3.0mm 19.7cps 6.8mm 15.4cps 13.8mm 10.0 cps This would...
  16. jim mcnamara

    Mars quakes lead to discovery of active fault zone

    https://www.nationalgeographic.com/science/2019/12/first-active-fault-system-found-mars2/ One insight on this is seismometers on Mars can provide data driven inferences about Mars deep crust structure with reliably located fault zones. Based on paper presented at AGU FallMeeting 2019 ...
  17. H

    How can second Schur's lemma lead to inequivalent representations?

    i am reading this paper. after equation 16 the author (Blasone) writes that In the thermodynamical limit this goes to zero, i.e. the Hilbert spaces con- structed over the respective vacuum states are orthogonal. From the second Schur’s lemma [33] it then follows that the two representations of...
  18. X3FeynmanAlfven

    Physics Masters Degrees that eventually lead to a career in Plasma Propulsion

    Hello, just wanted to know what is recommended after undergrad Physics to get into a career developing electric propulsion systems, or anything to do with Plasmas and future propulsion devices?
  19. R

    A Effect of High-Energy Particles on Lead

    Neil Comins in The Hazards of Space Travel states a 40-inch thick wall of lead would be needed to shield interplanetary travelers from the solar wind, coronal mass ejections, and cosmic rays. When lead is constantly bombarded with high energy charged particles, what changes occur to the lead?
  20. entropy1

    I In which cases does superposition lead to splitting of worlds?

    I don't know how to understand this: Suppose we measure the spin of an electron with apparatus M. M can yield spin-up or spin-down. According to MWI, M briefly becomes in superposition of measuring spin up and spin down. Extremely quick however, M gets split by the splitting into two universes...
  21. F

    When using a DMM to check for a short to ground, why do you need one lead on ground?

    Back in December, I made a thread with a related topic as this titled "Ohm reading when there is a short in the condenser motor". But the question of this thread is distinct from the topic of my "Ohm reading when there is a short in the condenser motor" thread. Therefore, I have decided it...
  22. Tesla1963

    I How does high level radiation affect lead acid batteries?

    During episode 2 of the HBO miniseries “Chernobyl”, the search lights held by the three technicians entering the area beneath the reactor eventually go out from exposure to radiation. If the search lights were powered by lead acid batteries, how does radiation interfere with and/or hasten the...
  23. V

    I Why does the Dirac equation lead to spin 1/2?

    Why does the derivation of the Dirac equation naturally lead to spin ½ particles? The equation is derived from very general starting assumptions, so which of these assumptions has to be wrong to give us a spin-0 or spin-1 particle? I have tried to search for an answer and got as far as this...
  24. T

    Thermal balance in calorimeter after adding lead

    Since ΔT is change in temperature, the container and it's contents and the led most have same temperature difference when the led is added. I tried by assuming that energy released by the led is same as the amount that container and it's contents absorb. Meaning Q1-Q2 = 0 => Q1 = Q2. $$ \Delta...
  25. G

    Solving for Thickness of Lead to Reduce Count Rate to 50

    Homework Statement The count-rate from a gamma source is measured to be 1000 counts per minute. When 1.0 cm of lead is placed between the source and the detector, the count rate is reduced to 100 counts per minute. What additional thickness of lead would have reduced the count-rate to 50 counts...
  26. M

    How to clean lead and tin off silver the smart way?

    Greetings electro chemistry wizards! A quick speculation here... should be easy to sort out whether feasible. I have nice old pocket watch made of sterling silver that some numpty tried to fix with soft solder - lead & tin i presume but god knows when repair was attempted so it could be newer...
  27. S

    Anode designation in a lead acid cell

    Hi, I am trying to determine the conventional cathode and anode designations for lead acid cells. From what I have researched: Anode is where current flows in the device, or where electrons flow out of. In a secondary cell the designations for anode and cathode are based on the discharge...
  28. Mr Davis 97

    Find which initial conditions lead to convergence

    Homework Statement Let ##b_1\in \mathbb{R}## be given and ##n=1,2,\dots## let $$b_{n+1} := \frac{1+b_n^2}{2}.$$ Define the set $$B := \{b_1\in\mathbb{R} \mid \lim_{n\to\infty}b_n \text{ converges}\}$$ Identify the set ##B##. Homework EquationsThe Attempt at a Solution I claim that ##B =...
  29. L

    Electrolysis of NaHCO3 solution with lead electrodes

    Hey. If i carry out electrolysis of saturated sodium bicarbonate solution with lead electrodes, will the lead electrodes will dissolve to form lead carbonate (or basic lead carbonate if temperature is higher) or the lead ions will migrate from anode to cathode and deposite there? I think that...
  30. I

    I Does invariance of proper time lead to the Lorentz transformation, or vice versa?

    Hi, I've seen several explanations for sr on youtube. But they all start off explaining from a different perspective. I was wondering how the fundamental postulates of sr lead to the invariance of proper time between frames, and also what "order" everything is derived in. For example, does the...
  31. B

    B Energy required to get 1 kg of lead to a given temp from 0 K

    <Moderator's note: Two threads merged. Please don't create multiple posts.> can anybody tell me how do I work out how much energy it takes to get an atom of say lead to a given temprature from 0 kelvin
  32. YoungPhysicist

    Wood/Glass/Metal Reusing Lead: Why is My Ingot Oxidizing?

    Recently I've been recycling lead from old bullets.But everytime I recast the molten lead to an ingot, its surface is oxidized, therefore I am losing lead every single time I reuse it. Are there simple solutions to this without using an atmosphere of noble gases?
  33. ZapperZ

    Cellphone Distraction in Classroom Can Lead to Lower Grades

    I wasn't sure if this should be in General Discussion, or in this forum. However, since it affects students and it depends on the classroom policy of the instructor, I thought it should be in here. This is something many of us instructors have to deal with, something that was never an issue...
  34. fluidistic

    I How come electrons and phonons lead to the heat equation?

    Phonons on their own lead to the common heat equation. One sees that for example in insulators or non doped semiconductors. However in metals (or conductors), the electrons are the ones that are mostly responsible for the heat transfer, which extremely surprisingly to me, is also of the form of...
  35. Muhammad Danish

    B Lead Bullet or Rubber Bullet?

    Which bullet of same momentum is more effective in knocking a bear down? Lead bullet or rubber bullet?
  36. T

    Photon attenuation in lead

    Homework Statement Calculate the fraction of photons absorbed from an attenuated beam of 0.5 MeV photons after it has gone through 1.3 cm of lead? The linear attenuation coefficient of lead for 0.5 MeV photons is 0.5 cm-1. Why is lead a good choice as a material for shielding? Homework...
  37. J

    Identify Condition of lag and lead compensator

    Homework Statement Homework Equations For lag compensator pole is dominating For lead compensator zero is dominating The Attempt at a Solution So for lag compensator: P1 is closer to origin than Z1, so mod of P1 < mod of Z1 So P1 > Z1 (since the poles and zeroes are negative) And for lead...
  38. J

    Car battery has no lead why

    Years ago I thought I would take apart a car battery melt all the lead I thought there would be at least 10 or more pounds of lead I only got a little over a pound of lead there was a lot of heavy dirt but applying heat to this material yielded no lead it seems the acid eats or corrodes the lead...
  39. A

    Selection of multi-pin connector for power lead cables

    Hi, I have 6 cables. Each cable has 3 wires: zero, phase, earth. Each cable supplies 320W 230VAC heater (I have 6 heaters). I am looking for 1 multi pin connector for all these cables for quick plug in/out. Link to example connectors...
  40. K

    I Why is gold heavier than lead?

    Not only are lead nuclei heavier than gold ones (207 vs 200), but the atoms are smaller (ionic radius 119pm vs 137pm). There is every reason for Pb to be heavier. Why is it lighter? (11.34 vs 19.31 g/cm^3) They both have a FCC crystal structure, so the packing should be equally efficient...
  41. R

    Length of a 60/40 soldering lead that is 1lb and 0.8mm dia?

    what is the Length of a 60/40 soldering lead that is 0.453kg and 0.8mm in diameter? i could not find the volume of the thing so is there any other way to go around this? i could also not find the density of the 60/40 solder. so yeah I am asking here if anybody knows thank you
  42. B

    Medical Decreasing IQ: Beware of Lead in US Food Supply

    Is lead in the US food supply decreasing our IQ? The environmental advocacy group Environmental Defense Fund (EDF) on June 15 released a study about dietary lead exposure, with a focus on food intended for babies and young children. Using a Federal Drug Administration (FDA) database of food...
  43. Adam Rabe

    Percentage transmittance gamma ray through lead

    Homework Statement Homework Equations I = Io e^-ux The Attempt at a Solution 0.75 = 1 * e^-u1 using algebra... u =2.117 I = 1 * e^-2.117*3 I = 0.00175 Answer is apparently 42.2. Can someone tell me where i went wrong? Thanks for any help as always
  44. C

    Why would I have 240 on one lead into breaker panel?

    I changed my breaker box and when I connected the two leads from the pole one is coming in at 120 and the other at 240. I did not change anything between the pole and incoming lead. What could have happened here and how do I trouble shoot / resolve this? The voltage out of the meter on the pole...
  45. wolram

    Lead in America's water supply

    https://trofire.com/2017/02/11/american-children-poisoned-lead-tainted-water/ I found this article very worrying, the lead is causing all sorts of maladies including violent behaviour, It seems that lead pipes that were laid in the civil war era are leaching out, Accelerated by chemical errosion.
  46. 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...
  47. 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...
  48. 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.