Silver
Silver is a chemical element with symbol Ag (Greek:άργυρος árguros, Latin:argentum, both from the Indo-European root *h₂erǵ- for "grey" or "shining") and atomic number 47. A soft, white, lustrous transition metal, it possesses the highest electrical conductivity, thermal conductivity and reflectivity of any metal. The metal occurs naturally in its pure, free form (native silver), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite.
Identity
- Atomic mass
- 107.868 u
- Category
- Transition metals
- Group
- 11
- Period
- 5
- Block
- d
- Oxidation States
- +1
- Phase (25 °C)
- Solid
- Appearance
- lustrous white metal
Electronic Structure
- Electron configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1 4d10
- Short configuration
- [Kr] 4d10 5s1
- Electrons per shell
- 2, 8, 18, 18, 1
- Electronegativity (Pauling)
- 1.93
- Electron affinity
- 126 kJ/mol
- 1st ionization energy
- 731 kJ/mol
- Ionization energies
- 731 · 2070 · 3361 kJ/mol
Physical properties
- Melting point
- 961.8 °C (1235 K)
- Boiling point
- 2161.8 °C (2435 K)
- Density
- 10.49 g/cm³
- Molar heat capacity
- 25.4 J/(mol·K)
Chemical behavior of silver
Silver has a singular electronic configuration ([Kr] 4d¹⁰ 5s¹), in which a 5s electron is incorporated into the 4d subshell to consolidate a closed, highly stable d layer. Its usual and most stable oxidation state is +1 (Ag⁺ cation), although under strongly oxidizing conditions it can also show +2 and +3. It is a noble metal of group 11 characterized by exceptional chemical inertness: it does not oxidize with molecular oxygen at room temperature, nor does it react with non-oxidizing acids. However, it shows an extraordinary chemical affinity for sulfur, becoming tarnished by traces of hydrogen sulfide in the environment.
Reactivity
4 Ag + 2 H₂S + O₂ → 2 Ag₂S + 2 H₂O
It tarnishes slowly when in contact with air containing traces of hydrogen sulfide, generating a very adherent black surface film of silver sulfide.
3 Ag + 4 HNO₃ → 3 AgNO₃ + NO + 2 H₂O
It dissolves easily in dilute nitric acid, releasing nitrogen monoxide and forming a transparent solution of silver nitrate.
Ag⁺ + Cl⁻ → AgCl
The silver cation reacts instantly with chloride ions in aqueous solution, forming a white, curdy precipitate of silver chloride, insoluble and light-sensitive.
2 Ag + 2 H₂SO₄ → Ag₂SO₄ + SO₂ + 2 H₂O
It is attacked by hot concentrated sulfuric acid, releasing sulfur dioxide gas and forming soluble silver sulfate.
Notable compounds
| Compound | Formula | Use or importance |
|---|---|---|
| Silver nitrate | AgNO₃ | Soluble salt precursor of silver compounds, corrosive antiseptic and reagent in chemical analysis |
| Silver chloride | AgCl | Light-sensitive salt used in pH reference electrodes, photochromic glass and optical instruments |
| Silver iodide | AgI | Crystal nucleation agent used in cloud seeding to cause rain or mitigate hail |
| Silver sulfadiazine | C₁₀H₉AgN₄O₂S | Essencial topical antibiotic for preventing infections in severe hospital burns |
| Silver oxide | Ag₂O | High-density energy material and stable voltage in silver-oxide button cells |
Electron shell distribution
View in the atom builderIsotopes
Natural silver consists of two stable isotopes in very similar proportions: silver-107 (¹⁰⁷Ag, with 60 neutrons and 51.84% abundance) and silver-109 (¹⁰⁹Ag, with 62 neutrons and 48.16%). About forty radioisotopes and numerous nuclear isomers have been synthesized; the metastable radionuclide silver-110m (¹¹⁰ᵐAg, half-life of 249.8 days) stands out, which is generated by neutron capture in structural components of nuclear reactors and serves as an industrial tracer of mechanical wear.
Occurrence and production
It is a scarce element in the Earth's crust (about 0.075 to 0.08 ppm), about twenty times more abundant than gold. It occasionally appears in native form as free metal, but its main sources are sulfide and sulfosalt minerals such as argentite (Ag₂S), pyrargyrite and quartz Argyrite (corneal silver, AgCl). More than two-thirds of the world's silver is obtained as a byproduct of the mining and electrolytic refining of copper, lead, zinc and gold ores. The main producing countries are Mexico, China and Peru.
History and origin of the name
Known and appreciated since prehistoric times (over 5,000 years old), silver was the premier coinage metal in empires such as the Greek, Roman and Spanish. Its chemical symbol Ag comes from the Latin word «argentum», which in turn comes from the Proto-Indo-European root «arg-», meaning bright, white or shining. Its Castilian name «plata» comes from medieval Latin «platus» (thin plane, thin sheet), a term used to refer to numismatic pieces and metal sheets.
Applications and relevance of silver
Uses of the element
It has the highest electrical conductivity, thermal conductivity and optical reflectivity of all known metals. More than half of world production is consumed in technology and industry: silver-conductive pastes for manufacturing photovoltaic solar cells, high-reliability electrical contacts, silver alloy soldered and printed circuit boards. It is also used in jewelry, silverware, precision telescope mirrors and minting of investment coins.
Uses of its compounds
Silver nitrate is the basis of photographic salts and bactericidal grafts; silver iodide is used in artificial weather modification (cloud seeding); and silver oxide powers quartz and pacemaker button cells. Medical dressings with silver nanoparticles and silver complexes fight multi-resistant hospital infections.
Health, safety and environment
Biological role
It has no known biological function in the human body. However, it has a recognized bactericide and antimicrobial power (oligodynamic effect) capable of destroying bacteria, fungi and viruses at very low concentrations, which is why it is incorporated into surgical instruments, medical catheters and advanced drinking water purification systems.
Safety
Metallic silver is biocompatible and harmless to skin. However, chronic occupational exposure or prolonged ingestion of soluble silver salts causes «argyria», an irreversible skin condition in which silver particles accumulate in the dermis, coloring the skin a striking grayish-blue.
Environment
Although harmless to mammals in moderate doses, the free ion Ag⁺ is extremely ecotoxic to aquatic organisms such as fish, crustaceans and microscopic algae. Therefore, the discharge of wastewater from photographic or nanotechnology processes is severely regulated by international environmental regulations.
Frequently asked questions about Silver
Why is silver the best conductor of electricity that exists?
In silver, atoms are arranged in a very ordered crystalline lattice and their outermost electrons have total freedom to move. When an electrical voltage is applied, this electron current flows almost without resistance or collisions with other atoms. Although copper is used more because it is more economical, silver is still the absolute champion in conductivity.
What is argyria and why can it change the color of the skin?
Argyria is a rare condition that can appear after prolonged exposure to high amounts of silver. The metal accumulates in certain tissues and, with exposure to light, can give the skin a grayish-blue tone that is usually permanent. It should not be confused with the superficial darkening of a silver jewel. Ingesting colloidal silver preparations is not a safe method to take care of health and can cause adverse effects.
Why is silver used in many solar panels?
Solar panels need electrical contacts that collect the current generated by light without losing too much energy. Silver conducts electricity very well, so it is used in fine metal lines in many solar cells. However, it is also an expensive material, and manufacturers investigate how to reduce the amount used or replace part of it with other materials without harming the performance of the panel.
Why are the mirrors of space and laboratory telescopes coated with silver or aluminum?
The glass of telescopes only provides polished mechanical support; the luminous reflection is performed by an atomic-layer metallic film deposited in vacuum. Silver is the best known reflector in the visible and near-infrared spectrum, reaching a reflectivity of over 99% in broad bands. This is why it is used in high-resolution infrared telescopes and in astronomical optics when the aim is to capture the maximum amount of photons from faint distant galaxies.
Why do silver cutlery and jewelry turn black?
Contrary to popular belief, silver does not darken because of the oxygen in the air. The real culprit is sulfur present in small amounts in the environment, from pollution, gases or even foods such as eggs. Silver reacts with these compounds to form a very thin black surface film of silver sulfide, which can be easily cleaned.
How is silver used to make artificial rain?
To stimulate rain in times of drought, planes or rockets disperse tiny silver iodide particles inside cold clouds. Because the crystals of this substance have a microscopic shape almost identical to that of ice, the cloud water vapor condenses quickly over them, forming drops or snowflakes that fall by gravity to the ground.
How does silver help to combat microbes in some medical dressings?
Some dressings contain silver and release small amounts of ions of this metal when in contact with the wound. These ions can interfere with proteins and other components of certain bacteria, making their growth difficult. Silver dressings are used in specific clinical situations, but they are not necessary for all wounds and do not guarantee the elimination of any microorganism. Its choice depends on the lesion and the criterion of the health professional.
Main sources consulted: PubChem, Royal Society of Chemistry, NIST, IUPAC. Last revision: November 2026.