What is Gold: Definition and 195 Discussions

Gold is a chemical element with the symbol Au (from Latin: aurum) and atomic number 79, making it one of the higher atomic number elements that occur naturally. In a pure form, it is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Chemically, gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold often occurs in free elemental (native) form, as nuggets or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the native element silver (as electrum), naturally alloyed with other metals like copper and palladium and also as mineral inclusions such as within pyrite. Less commonly, it occurs in minerals as gold compounds, often with tellurium (gold tellurides).
Gold is resistant to most acids, though it does dissolve in aqua regia (a mixture of nitric acid and hydrochloric acid), which forms a soluble tetrachloroaurate anion. Gold is insoluble in nitric acid, which dissolves silver and base metals, a property that has long been used to refine gold and to confirm the presence of gold in metallic substances, giving rise to the term acid test. Gold also dissolves in alkaline solutions of cyanide, which are used in mining and electroplating. Gold dissolves in mercury, forming amalgam alloys, and as the gold acts simply as a solute this is not a chemical reaction.
A relatively rare element, gold is a precious metal that has been used for coinage, jewelry, and other arts throughout recorded history. In the past, a gold standard was often implemented as a monetary policy, but gold coins ceased to be minted as a circulating currency in the 1930s, and the world gold standard was abandoned for a fiat currency system after 1971.
A total of 197,576 tonnes of gold exists above ground, as of 2019. This is equal to a cube with each side measuring roughly 21.7 meters (71 ft). The world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold's high malleability, ductility, resistance to corrosion and most other chemical reactions, and conductivity of electricity have led to its continued use in corrosion resistant electrical connectors in all types of computerized devices (its chief industrial use). Gold is also used in infrared shielding, colored-glass production, gold leafing, and tooth restoration. Certain gold salts are still used as anti-inflammatories in medicine. As of 2017, the world's largest gold producer by far was China with 440 tonnes per year.

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  1. pinball1970

    Is This the Most Significant Gold Discovery in Norway's History?

    "Associate professor Håkon Reiersen with the museum said the gold pendants—flat, thin, single-sided gold medals called bracteates—date from around A.D. 500, the so-called Migration Period in Norway, which runs between 400 and about 550, when there were widespread migrations in Europe." Found by...
  2. Estefani

    Synthesis of Fluorescents AuNCs

    Hi everyone, as a degree project to obtain a chemistry degree, i am developing the Synthesis of Fluorescent Gold Nanoclusters (AuNC). I have investigated the route to obtain nanoestructures of nanometric size less than five nanometers, reaction conditions, and so far i have managed to obtain a...
  3. G

    Teach Kids 'Financial Responsibility' Not Debt

    "As good as gold." - Charles Dickens "You cannot teach debt to children." - anon So I read not too long ago a bit on the debate on returning to the gold standard during the Reagan administration and the issuing of gold bonds by the Treasury. Then I began questioning the nature of the gold...
  4. dcolt319

    Can Gold Oxalate Be Synthesized Using Oxalic Acid and Gold (III) Chloride?

    Hello, I'm trying to find a way to form gold oxalate. I'm wondering if anyone has any information on reacting oxalic acid with gold (III) chloride. The literature on this reaction is quite sparse, and I'm curious if simply combining aqueous solutions of the salt and acid would precipitate the...
  5. Astronuc

    Rare gold coin from 1420s discovered in Newfoundland, Canada

    Edward Hynes was scanning the coast of Newfoundland, Canada, with a metal detector when he got a signal. He dug a hole and found a shiny gold object. https://www.cbc.ca/news/canada/newfoundland-labrador/old-gold-coin-nl-1.6646200...
  6. tbn032

    B Exploring the Alpha Particle-Electron Interaction in Gold Foil Experiments

    My current understanding: The mass of alpha particle is approximately 7340.6 times higher than the mass of electron.in the gold foil scattering experiment the deflection of alpha particle due to electron is approximately zero. The reason that is given is that since the electron is much lighter...
  7. S

    Solid State Researching Gold Thin Films: Electrical & Optical Properties

    Hi Physics folks,I am currently collecting resources for my senior seminar project at my university and would like to ask if anyone has any good references for gold thin films. I am planning on focusing primarily on the electrical and optical properties of gold thin films. I appreciate any...
  8. Addez123

    I Distribute gold among items depending on demand

    This turned out to be more difficult than I thought! Right now my calculations for the price for each item: price = (1 - demand/totalDemand) * goldToDistribute It doesn't work, example case: goldToDistribute = 10 a.demand = 10 b.demand = 90 c.demand = 100 totalDemand = 200 a.price = (1 -...
  9. LCSphysicist

    Do you know if this plug for gold wire is still selling on the market?

    We are dealing with extremelly thin (radius of order in mm) wires of gold at the project i am. It is necessary to plug these wires at a copper plataform. We have think two ways to do that: To weld it, or, to buy a plug that allow us to do that. SInce to weld it is the second option, we are...
  10. Astronuc

    Farmer looks for hammer, finds gold and silver in Hoxne, Suffolk

    In 1992, Suffolk-resident Eric Lawes and retired farmer, went looking for a missing/misplaced hammer. https://www.thevintagenews.com/2019/04/16/hoxne-hoard/ Lawes discovered what became known as the Hoxne Hoard, "close to 60 pounds of items made from silver and gold were found on the site...
  11. Astronuc

    In Medieval Africa, A Unique Process for Purifying Gold With Glass

    Medieval Africans Had a Unique Process for Purifying Gold With Glass And scientists in Illinois have recreated it. https://www.atlasobscura.com/articles/medieval-african-gold Mansa Musa, emperor of Mali from 1312 to 1337, was widely known for his vast wealth in the form of gold deposits...
  12. bland

    I Can we accurately predict the properties of gold?

    Let us assume magically that elements 77 to 79 do not exist on Earth, and we ignore any other consequences for the purposes of this query. Without actually making gold to see, is our understanding of QED sufficient to be able to look at Hg as a silvery metallic liquid and work out all the unique...
  13. Astronuc

    Henry III gold penny found in Devon, UK

    Metal Detectorist Discovers One of England’s Earliest Gold Coins in a Farm Field https://www.smithsonianmag.com/smart-news/800-year-old-gold-penny-found-in-english-field-could-sell-for-half-a-million-180979420/ I like the term 'detectorist'. Like an astronomer is a 'star or stellar...
  14. S

    Weight of gold chain when dropped on a weighing scale

    The force exerted downwards on the scale by the chain when it is kept on it would be Fg= Mg =λLg where λ is the linear mass density However when the chain is dropped onto the scale it exerts an additional force due to its change in momentum The force exerted by each part of the chain would...
  15. john56789

    I How Long Does It Take to Melt a 12.5 kg Gold Bar at 3000°C?

    how long does it take a 12.5 kg gold bar to melting at 3000 degree C°? Why does the water coming out of the waterjet slow down after a while?
  16. R

    Gold jewelry and fertility issues

    Hello! According to recent studies, gold nanoparticles play a negative role on male fertility (reducing the motility of sperm cells, among other things), So, the question is, is the amount of gold absorded from donning gold jewerly enough to have noticeable spermatotoxic effects?
  17. docnet

    How to increase a hole/thread diameter in gold

    Hello, I am trying to change a 0.9mm screw with a 1.0mm screw. The material is 18k gold, and so the hole is to be threaded. Is it ill advised to force the larger screw in without tapping the smaller hole? the difference in screw size is just .1mm, and we assume the thread pitches are...
  18. jedishrfu

    B There's Gold in Them Neutron Stars - or - Maybe Not

  19. J

    A Relativistic Effects for Copper and Gold

    Summary: Relativistic effects on the quantum states of electrons in Copper and Gold Hello. I am a new member. I have read that the explanation for the colors of copper(red) and gold(yellow) compared to other metals being silver or grey in color is due to relativistic effects on the valence...
  20. Skyland

    The Possibility of Value in Amalgam Alloys of Gold, Copper and Silver

    Would using mercury to form amalgam alloys combining gold, copper, and silver have any electronic value? Has this amalgam ever been made and tested in conductivity and Malleability? Or would it just be an expensive filling?
  21. M

    Find the area and length of a gold leaf

    Homework Statement Gold, which has a density of 19.32 g/cm3, is the most ductile metal and can be pressed into a thin leaf or drawn out into a long fiber. (a) If a sample of gold with a mass of 3.872 g, is pressed into a leaf of 5.372 μm thickness, what is the area of the leaf? (b) If...
  22. S

    Why do copper, gold and cesium have special colors?

    Because metals have free electrons, so they have almost continuous energy states going up and down different energy levels and repeating themselves, most metals are silver-white, right?But why do gold, copper, and cesium have special colors? I wanted to know more about this, so I studied the...
  23. T

    Thermal Resistance between Chip to Gold Tin Solder

    I'm currently doing a heat sink calculation design and having a little confused moment with the area of the chip with a AuSn (Gold Tin Solder) pre-cut that's attached to the bottom of the chip. I've tried looking around online for AuSn's thermal resistance value, but there is none besides a...
  24. R

    Alpha particle approaching a gold nucleus

    Homework Statement An alpha particle approaches at high speeds a gold nucleus with a charge of 79e. What is the electric force acting on the alpha particle when it is 2.0e-17 m from the gold nucleus? Homework Equations FE=k(q1q2)/d2 The Attempt at a Solution FE=k(q1q2)/d2...
  25. K

    B Rutherford's Gold Foil Alpha Particle Interactions

    Hi All, I am asking this question as a lay man based on the questions which my 10 year old kid raised while explaining alpha ray scattering experiment. As Alpha particle is a high energetic particle when it interacts with electron of gold atom it ejects the electron. Is there any probability if...
  26. P

    B Geiger's Gold Foil Experiment: Exploring Atom Structure

    Hi, I'm confused a little about the gold foil experiment. I tried to put myself in Geiger's shoes, the author of the experiment. I'm firing alpha particles at a gold film, given that the plum pudding model is the pinnacle of human understanding of the atom, meaning I believe matter is made of...
  27. R

    Is a gold electrode supposed to corrode during electrolysis?

    Help! I was under the assumption that a gold electrode for oxygen would be able to sustain water electrolysis with sodium bicarbonate as the electrolyte without degrading, so I bought a foot long of 28 gauge 24k(pure gold) wire, but I've been putting it to the test for about 30 minutes and it's...
  28. T

    What is the Best Lubricant for Extending the Life of Gold Plated Contacts?

    Can anyone recommend a lubricant for extending the life of frequently cycled (once per day) gold plated contacts? It's low voltage (couple volts), but exposed to some moisture so if the plating wears through it corrodes.
  29. 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...
  30. P

    B Some Questions About Gold Nanoparticles

    Hello! I am in my last year of high school physics, and for our final project we are given the opportunity to research a topic we are interested in. My chosen subject is the use of gold nanoparticles in cancer treatment. Although I have just begun my research, I am having a tough time finding...
  31. S

    A Adhesion mechanism between titanium and gold?

    Hi all, I sputtered titanium (10 nm) - gold (~ 100 nm) films at room temperature on oxidized silicon substrates. The titanium acts as an adhesion promoter between the SiO2 and the gold film. My Question: What is the adhesion mechanism between the titanium and gold film at room temperature...
  32. F

    Alpha Particle Approaching a Gold Nucleus

    Homework Statement An alpha-particle with velocity 3.5 x 106 strikes a block of gold, atomic number 79 and mass number 197. Find the distance of the closest possible approach between the alpha particle and a gold nucelus, assuming Coulomb's law holds over such distances. Assume mp = mn = 1.67 x...
  33. Joshua L

    What are the considerations for analyzing current through thin gold wires?

    Hey all, I've been thinking of a couple scenarios that involve thin wires (ones that have their diameter in the order of 1 mm). Suppose a gold wire with length L and diameter D is suspended straight in room temperature air and connected to some voltage V. Thus, a current will pass through the...
  34. P

    Archimedes Principle: Pure gold or not?

    Homework Statement Archimedes, prove your stuff. A royal crown (cola?) of pure gold is suspended in air by a thread and the tension in the thread is of magnitude T. When the crown is totally immersed in water, the magnitude of the tension in the thread is 0.872T. A) sketch a second law force...
  35. R

    Ultra thin silver and gold foil

    does anyone know where to buy ultra thin (0.024" or less) large silver and gold foil squares (like 7"'x7" for gold/silver and up to 3'x6' for silver)? Looking into large and small sputtering and sealing around a large surface area of metal and connecting the electrode outside the vacuum is...
  36. tensor0910

    Gold Status Delay: Is It Normal to Wait 4 Days for Activation?

    Paid for 6 months of gold, but still nothing showing up. Emailed Customer Support, and no word yet. Is this normal? This is all in a span of about 4 days.
  37. T

    B Gold Synthesis in Supernovae: What Form Does It Take and Under What Conditions?

    Do we know a what stage of a supernova gold is synthesized? And when the gold is ejected, are we talking about pebble size chunks of gold or mostly dust that later coalesce?
  38. sam ham

    B Specific Gravity of Various Types of Gold

    Hi guys. This is my first time posting, so I am sorry if it is in the wrong section. My professor wants me to fin the specific gravity's for gold of 10 karat through 24 karat. He hasn't given us the mass or anything, he just says that we should be able to look them up online. I've been looking...
  39. P

    New solution found for Gold extraction

    No mention of this here so far that I see so I would like to see what the experts know about this. A Univeristy of Saskatchewan professor claims he has invented a solution, "acetic acid combined with very small amounts of an oxidant and another acid", that can rapidly remove plated gold from...
  40. epenguin

    The white and gold / Blue and black dress

    I'm sure we discussed this optical illusion, which went viral, here. Here an update and some background of how it came about which most of us probably didn't know; it is now a matter of lawsuits. http://www.bbc.co.uk/search?q=TheDress
  41. X

    Elastic collision between alpha particle and gold Nuclei

    Homework Statement When an alpha particle collides elastically with a nucleus, the nucleus recoils. Suppose a 3.94 MeV alpha particle has a head-on elastic collision with a gold nucleus that is initially at rest. What is the kinetic energy of (a) the recoiling nucleus and (b) the rebounding...
  42. Oribe Yasuna

    Alpha Particle & Gold Nucleus Collision

    Homework Statement An alpha particle (a helium nucleus, containing 2 protons and 2 neutrons) starts out with kinetic energy of 10.5 MeV (10.5x106 eV), and heads in the +x direction straight toward a gold nucleus (containing 79 protons and 118 neutrons). The particles are initially far apart...
  43. saranya_sarah

    Why gold rings are not made from 100% gold?

    1. The problem statement, all variables and given/known dat Why gold rings are not made from pure gold but mixed with other metals? Homework EquationsThe Attempt at a Solution [/B]my answer...because when two elements are combined chemically they produce a new compound and this avoids...
  44. S

    Two rods are connected one silver and the other gold.

    Two metal rods, one silver and the other gold, are attached to each other. The free end of the silver rod is connected to a steam chamber, with a temperature of 100oC, and the free end of gold rod to a ice water bath, with a temp of 00 C. The rods are 5.0 cm long and have a square cross-section...
  45. gracy

    Gold leaf electroscope problem

    Homework Statement http://www.physicstutorials.org/home/electrostatics/electroscope Negatively charged electroscope and X-Y plates are placed like in the figure given below. If the distances between electroscope and conductor plates are equals; find the types of charges of plates for given...
  46. gracy

    Current in metal rod of gold leaf electroscope -- is it there?

    In gold leaf electroscope from the following video I have a doubt From time 2:11 to 2:14 flow of negative charge i.e flow of electron won't it cause current?
  47. M

    High Spin: Unraveling the Mystery of Mono Atomic Gold

    What does 'high spin' mean? I have heard of mono atomic gold having unusual properties. What is going on inside the atom?
  48. A

    Anyone got Graph for attenuation coefficient gold?

    Hello, does anyone have a graph for the attenuation coefficient of Gold (Au) (y-axis) with the respective types of interactions with photons of various energies usually from~10^-3 to 10^4 MV (x-axis) and where the incoherent, photoelectric, compton etc...interactions occur? Doing work on this...
  49. S

    What Is the Correct Debye Temperature Calculation for Gold?

    Homework Statement Calculate the Debye temperature for gold Homework Equations $$Θ_D = \hbar \frac{v_s}{k_b} \sqrt[3]{6π^2 \frac{N}{V}}$$ Speed of sound in gold: $$v_s=3240 m/s$$ The Attempt at a Solution I used the equation for ΘD and for the concentration I used the value for atom density...
  50. O

    Gold Electrodes and Capacitance

    Homework Statement Well its 2 questions: Immersing a pair of gold electrodes in a saline solution in the presence of a fixed voltage causes the capacitance to: IncreaseDecreaseRemain unalteredIncrease briefly and then return to its original value Immersing a pair of gold electrodes in a...