What is Cu on the Periodic Table?

Copper (symbol: Cu) is a chemical element with atomic number 29. It belongs to the transition metals group and sits in Period 4, Group 11 of the periodic table. The symbol Cu comes from Cuprum, the Latin name derived from Cyprus (Kypros), an island that was once the primary source of copper for the Roman Empire.

Copper's Basic Properties

  • Atomic Number: 29
  • Atomic Mass: 63.546 u
  • Category: Transition Metal
  • Group: 11 | Period: 4
  • Melting Point: 1,084.6°C (1,984.3°F)
  • Boiling Point: 2,562°C (4,644°F)
  • Density: 8.96 g/cm³
  • Electron Configuration: [Ar] 3d¹⁰ 4s¹

Why is Copper's Symbol Cu and Not Co?

Many students wonder why copper's symbol is Cu instead of Co. The reason is historical — chemical symbols come from Latin names. Copper's Latin name is Cuprum, so Cu. The symbol Co is already taken by Cobalt (atomic number 27). Other elements with Latin-based symbols include Iron (Fe from Ferrum), Lead (Pb from Plumbum), and Gold (Au from Aurum).

Copper's Electron Configuration

Copper has an interesting electron configuration: [Ar] 3d¹⁰ 4s¹. You might expect it to be [Ar] 3d⁹ 4s², but copper "borrows" one electron from the 4s orbital to fully fill the 3d orbital. A completely filled 3d orbital is more energetically stable — this is why copper is an exception to normal electron filling rules.

Where is Copper Used?

  • Electrical wiring: Copper is the second-best electrical conductor after silver, but much cheaper. Over 60% of all copper produced goes into electrical applications.
  • Plumbing: Copper pipes are used in homes worldwide because copper resists corrosion and kills bacteria.
  • Alloys: Bronze (copper + tin) and Brass (copper + zinc) are two of history's most important alloys.
  • Coins: Most coins contain copper. Even "silver" coins are usually 92% copper.
  • Electronics: Printed circuit boards, computer chips, and motors all use copper.

Copper's Charge on the Periodic Table

Copper commonly forms two ions: Cu⁺ (copper(I) or cuprous) and Cu²⁺ (copper(II) or cupric). Cu²⁺ is more common in compounds. The blue color of copper sulfate (CuSO₄) solutions comes from the Cu²⁺ ion.

Fun Facts About Copper

  • The Statue of Liberty is clad in 80 tons of copper. Its green color (called patina) formed as the copper oxidized over decades.
  • Copper is naturally antibacterial — copper surfaces kill bacteria within hours, which is why hospital door handles are often made of copper.
  • The human body contains about 75–100 mg of copper, essential for enzyme function and red blood cell production.
  • Copper was the first metal worked by humans, dating back to 9000 BC in the Middle East.

Copper in the Periodic Table Context

Copper sits between Nickel (Ni, 28) and Zinc (Zn, 30) in Period 4. Above it is Silver (Ag, 47) and below it is Gold (Au, 79) — all three are in Group 11 and are excellent electrical conductors. This group is sometimes called the "coinage metals" because all three have historically been used as currency.