Periodic Table and Technical information:
Atomic Number =79
Atomic Weight =196.9665 g/atom
Density (at 293 K) =19.32 g/cm3
Melting Point =1337.33 degrees Kelvin
Melting point =2,063 degrees Fahrenheit
Specific gravity is 19.32
Tensile strength =19,000psi
Hardness =2.75 on Mohs scale
Is one of the "Transition Metals" Boiling Point =2807.8 C (1337.59 K)
Modulus of Elasticity =79 G Pa
Brinell Hardness (annealed to 1031 K) =25 kgf/mm2
Reflectance at 0.40 um =38.7%
Reflectance at 0.55 um =81.6%
Reflectance at 0.70 um =96.7%
Reflectance at 1.00 um =98.1%
Thermal Expansion (from 273 to 373 K) =1.416 x 10^-7 K-1
Thermal Conductivity (at 273 K) =3.144 W/cm x K
Electrical resistivity (at 273 K) =2.05 x 10^-6 ohm x cm
Heat of Fusion =1.268 x 104 J/g-atom
Heat of Evaporation (at 298 K) =3.653 x 105 J/g-atom
Heat Capacity at 298 K =0.1288 J/g x K
Magnetic Moment =0.1439 N x m
Standard Oxidation Potential (Au to Au+ + e) =-1.68 V
Total Emissivity (from 493 to 893 K) =0.018 to 0.035
Properties of Gold:
Out of the earth comes a remarkable metal with an unparalleled combination of chemical and physical properties that make this metal invaluable to a wide range of everyday applications essential to our modern life. Thousands of common, everyday appliances require gold to ensure perfect performance over a long period of time. This indestructible metal is completely recyclable and virtually immune to the effects of air, water, and oxygen. Gold will not tarnish, rust, or corrode. This unique combination of properties makes gold a vital component in many medical, industrial, and electrical applications.
Resistance to Corrosion:
Gold is the most non-reactive of all metals. It is benign in all natural and industrial environments. Gold never reacts with oxygen (one of the most active elements), which means it will not rust or tarnish. The gold death-mask in the tomb of Tutankhamen looked as brilliant when it was unearthed in 1922 as when it was entombed in 1352 BC.
Gold is among the most electrically conductive of all metals. Since electricity is essentially the flow of charged particles in a current, metals that are conductive allow this current to flow unimpeded. Gold is able to convey even a tiny electrical current in temperatures varying from -55° to +200° centigrade. This makes gold a vital component for electrical connectors in computers and telecommunications equipment.
Ductility and Malleability:
Gold is the most ductile of all metals, allowing it to be drawn out into tiny wires or threads without breaking. As a result, a single ounce of gold can be drawn into a wire five miles long. Gold's malleability is also unparalleled. It can be shaped or extended into extraordinarily thin sheets. For example, one ounce of gold can be hammered into a 100 square-foot sheet.
Infrared (Heat) Reflectivity:
Gold is the most reflective and least absorptive material of infrared (or heat) energy. High purity gold reflects up to 99% of infrared rays. This makes gold ideal for heat and radiation reflection, as in life-saving face shields for astronauts and firefighters.
Gold is also an excellent conductor of thermal energy or heat. Since many electronic processes create heat, gold is necessary to transfer heat away from delicate instruments. For example, a 35% gold alloy is used in the main engine nozzle of the Space Shuttle, where temperatures can reach 3300° centigrade. Gold alloy is the most tenacious and long-performing material available for protection at these temperatures.
If an item is described as "gold filled", or "gold overlay", that means that a layer of at least 10-karat gold permanently bonded by heat and pressure to one or more surfaces of a support metal, then rolled or drawn to a prescribed thickness. The karat gold must be at least 1/10 by weight of the total metal content.
Rolled Gold Plate:
Material consisting of a layer of plating of 10-karat gold or better which is mechanically bonded to a base metal. The karat gold content may be less than 1/20 but must be properly identified by weight in terms of total metal content.
Gold at least 15- micro-inches thick, bonded to sterling silver by an electrolytic or mechanical process.
Pure gold that is pounded into sheets applied to other surfaces by hand. Usually about 3 micro-inches thick.
Is not gold at all. It is a gold colored mineral found in other rocks like gold often is. It is really iron pyrite and in relation to gold is worthless.
The Acid Test:
This is an expression that has entered popular language and means the final proof, or undeniable. It comes from the need to be able to quickly and positively determine not only if an item is truly gold or not, but also what karat it is. One of gold's enduring qualities is that it does not tarnish or oxidize easily. Nitric acid does affect gold and when applied in different concentrations, can provide nearly infallible answers to questions of karat.
Below is a list of the popular units of measure when referring to gold weight:
Grains (gr): This name originated from the weight of a dried seed of corn or as some believe a grain of wheat.
1 grain = 64.8 milligrams
24 grains = 1 Pennyweight
1 gram = 15.432098 grains
Pennyweight (dwt): This name originated from the weight of an Anglo Norman silver penny in medieval England.
1 pennyweight = 24 grains
= 1.5552 grams
Ounce (oz) Av.:
1 ounce (Av) = 437.5 grains
= 28.35 grams
= 18.2291 pennyweight
Ounce (oz) Troy:
1 ounce (Troy) = 480 grains
= 31.104 grams
= 20 pennyweight
1 pound (Av) = 7000 grains
= 453.6 grams
= 291 2/3 pennyweight
= 16 ounces (Av)
1 pound (Troy) = 5760 grains
= 373.248 grams
= 240 pennyweight
=12 ounces (Troy)