Copper Element Properties
Complete reference for copper (Cu, element 29): atomic data, electron configuration, isotopes, physical constants, oxidation states, and a property unit converter.
Copper
Transition Metal — Period 4, Group 11
Atomic Identity
Periodic Table Locator — Period 4 Neighborhood (d-block)
Copper (Z=29) sits between nickel (Z=28) and zinc (Z=30) in Period 4. It is directly below silver (Z=47) and above gold (Z=79) in Group 11 of the d-block — the coinage metals triad.
Electron Configuration
Full 3d¹⁰ stabilizes the atom — 4s has only 1 electron
Key Isotopes of Copper
| Isotope | Symbol | Protons | Neutrons | Mass (u) | Abundance | Stability |
|---|---|---|---|---|---|---|
| Copper-63 | ⁶³Cu | 29 | 34 | 62.9295975 | 69.17% | Stable |
| Copper-64 | ⁶⁴Cu | 29 | 35 | 63.9297642 | Radioactive |
Unstable
β⁺/β⁻, EC; t½ = 12.70 h — PET imaging tracer |
| Copper-65 | ⁶⁵Cu | 29 | 36 | 64.9277895 | 30.83% | Stable |
| Copper-67 | ⁶⁷Cu | 29 | 38 | 66.9277303 | Radioactive |
Unstable
β⁻ decay; t½ = 61.83 h — cancer therapy |
Copper has only two stable isotopes, Cu-63 and Cu-65. Cu-64 is a clinically important radioisotope used in PET imaging and targeted cancer radiotherapy due to its favorable half-life and dual beta emission. Cu-67 is under active investigation as a therapeutic radioisotope for antibody-directed cancer treatment.
Physical Properties
Chemical Properties
Oxidation States of Copper
| State | Ion / Form | Example Compound | Notes |
|---|---|---|---|
| 0 | Cu⁰ | Cu metal, Cu(CO)₄ (carbonyls) | Native copper; organometallic compounds |
| +1 | Cu⁺ (cuprous) | CuCl, CuBr, Cu₂O, CuCN | Stable in insoluble salts; disproportionates in solution |
| +2 | Cu²⁺ (cupric) | CuSO₄·5H₂O, CuO, CuCl₂, Cu(OH)₂ | Most stable aqueous state; blue color in solution |
| +3 | Cu(III) | CuF₃, LaCuO₃ (cuprate superconductors) | Found in high-temperature superconductors |
| +4 | Cu(IV) | Cs₂CuF₆ (rare) | Extremely rare; only in strongly oxidizing conditions |
Ground State Quantum Numbers
Notable Emission Lines
In a flame test, copper produces a distinctive blue-green flame. The resonance lines at 324.75 nm and 327.40 nm are primary lines used in atomic absorption spectroscopy (AAS) for copper determination in environmental and industrial samples.
Property Unit Converter
Convert common copper property values between units. Enter a value and select the conversion.
Common Copper Compounds
| Compound | Formula | Common Name | Key Uses |
|---|---|---|---|
| Copper(II) sulfate pentahydrate | CuSO₄·5H₂O | Blue vitriol / bluestone | Fungicide, electroplating, swimming pool algaecide, lab reagent |
| Copper(I) oxide | Cu₂O | Cuprite | Red pigment, antifouling paint, rectifier in electronics |
| Copper(II) oxide | CuO | Black copper oxide | Pigment, catalyst, Li-ion battery anode material |
| Copper(II) chloride | CuCl₂ | Copper dichloride | Lewis acid catalyst, wood preservative, food coloring (E141) |
| Copper(I) chloride | CuCl | Nantokite | Catalyst for Sandmeyer reactions, flame colorant |
| Copper(II) hydroxide | Cu(OH)₂ | Cupric hydroxide | Fungicide (Bordeaux mixture with CaSO₄), battery electrode |
| Copper(II) carbonate | CuCO₃ | Malachite (basic form) | Green pigment, copper ore mineral, art pigment |
| Copper(II) nitrate | Cu(NO₃)₂·3H₂O | Cupric nitrate | Electroplating, light-sensitive coatings, wood preservative |
Key Facts About Copper
Humanity's Oldest Metal
Copper artifacts date to around 8700 BCE, making it the oldest metal in recorded human use. Its occurrence as native metal (pure metallic nuggets) meant no smelting was required initially. The subsequent Chalcolithic (Copper Age) and Bronze Age (~3300–1200 BCE) defined entire civilizations. Copper axes, tools, mirrors, and coins underpinned ancient economies from Mesopotamia to the Americas.
The Coinage Metals Triad
Copper, silver, and gold form Group 11 of the periodic table and share a completed inner d-subshell. All three have been used as coinage for millennia due to their rarity, malleability, corrosion resistance, and attractive appearance. Copper's positive standard reduction potential (+0.34 V) means it does not dissolve in dilute acids, a key property that made bronze coins durable. The US penny was nearly pure copper until 1982.
World's Best Practical Conductor
Silver (Z=47) has slightly higher conductivity than copper, but copper's lower cost and higher abundance make it the de facto standard for electrical wiring. The world consumes over 25 million tonnes of copper per year, with roughly 65% used in electrical applications. A typical home contains about 45 kg of copper wiring. Electric vehicles use 3–4× more copper per vehicle than internal-combustion cars.
Green Patina: Natural Protection
When copper is exposed to air and moisture over years, it develops a green patina called verdigris — a mixture of copper carbonates, hydroxides, and sulfates (mainly Cu₂CO₃(OH)₂ malachite). Unlike iron rust, copper patina is chemically stable and forms a protective layer that actually slows further corrosion. Famous examples include the Statue of Liberty (81 tonnes of copper sheets), the British Museum roof, and many historic church domes.
Essential Trace Element in Biology
Copper is biologically essential in trace amounts. It is the active metal in hemocyanin (the oxygen carrier in many mollusks and arthropods, analogous to hemoglobin in vertebrates), cytochrome c oxidase (mitochondrial Complex IV), superoxide dismutase (antioxidant enzyme), and ceruloplasmin (copper transport protein in blood). The adult human body contains about 100 mg of copper, mostly in the liver, brain, and muscle.
Antimicrobial Copper Surfaces
Copper and its alloys exhibit oligodynamic antimicrobial activity — surfaces kill bacteria, fungi, and many viruses within 2 hours of contact. The EPA has registered over 500 copper alloys as antimicrobial. During the COVID-19 pandemic, research showed SARS-CoV-2 survived on plastic for up to 72 hours but was inactivated on copper within 4 hours. Copper door handles, railings, and hospital surfaces are increasingly deployed in healthcare settings.
Summary
Complete reference for copper (Cu, element 29): atomic data, electron configuration, isotopes, physical constants, oxidation states, and a property unit converter.
How it works
- Browse the atomic identity card for symbol, atomic number, and standard atomic weight.
- Check the electron configuration panel for orbital notation and the anomalous [Ar] 3d¹⁰ 4s¹ arrangement.
- Review the isotopes table for stable and notable radioactive isotopes with natural abundances.
- Consult the physical and chemical properties panels for melting point, density, ionization energies, and oxidation states.
- Use the interactive unit converter to convert copper property values between common units.
- Explore the key facts section for industrial context and interesting chemistry of copper.
Use cases
- Look up copper constants for chemistry homework, metallurgy, or materials science work.
- Verify atomic data when writing lab reports or research papers.
- Reference isotope data for radiochemistry or nuclear research.
- Convert melting and boiling points between Celsius, Fahrenheit, and Kelvin.
- Study anomalous d-block electron configurations using copper as the canonical example.
- Confirm oxidation states (+1, +2) for writing ionic formulae or balancing redox equations.
- Research copper compounds for industrial chemistry, biology, or environmental science.
- Quick-reference ionization energies for electrochemistry or spectroscopy calculations.