All practice pages/Interatomic theory/Elements
Element 29, a transition metal
The first metal people worked, the wire in nearly every electric cable, and the reason the Statue of Liberty is green.
Period 4, group 11. The other transition metals are tinted, and every cell opens its own article.
Copper has 29 electrons, one for every proton, so the atom carries no charge. Below are the same 29 electrons written two ways.
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹
Short form: [Ar] 3d¹⁰ 4s¹, where [Ar] stands for the 18 electrons argon already has.
That list runs by shell. In the order the subshells fill it reads [Ar] 4s¹ 3d¹⁰, because a subshell fills by its energy, not by its shell number.
The simple form counts electrons shell by shell. The orbital form says which subshell each one sits in: s holds 2, p holds 6, d holds 10 and f holds 14. Shell 3 here is 3s² 3p⁶ 3d¹⁰, and 2 + 6 + 10 is 18.
Copper sits in period 4 and has 4 shells. The period number counts the shells.
The outer shell holds 1 electron. Those are the ones copper can lose, gain or share, so they are the ones that decide what it bonds with.
Like other transition metals, copper loses its outer s electrons, and often some d electrons as well, to form positive ions, and it can form more than one kind.
Sometimes found as pure native copper, but mostly mined from sulfide ores such as chalcopyrite (CuFeS₂); Chile is the largest producer. Your body needs a little copper for enzymes, and octopuses, crabs and snails carry oxygen with a copper protein, hemocyanin, which turns their blood blue.
Used for about 10,000 years; copper beads from the Middle East date to around 9000 BCE, and mixing it with tin to make bronze began the Bronze Age. The Romans got much of their copper from Cyprus and called it aes Cyprium, Cyprus metal, later cuprum, which gives the symbol Cu.
Most goes into electrical wiring, motors and electronics, because only silver conducts electricity better. It also makes water pipes, roofing and heat exchangers, and alloys: brass with zinc and bronze with tin. Copper surfaces kill many bacteria, and the green patina on old copper roofs and statues protects the metal beneath.