What is copper? - Why do we use copper for electric wires?
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What is Copper?

Copper atom
Diagram of a copper atom

Copper is a kind of atom that has only one electron in the outermost ring. Copper is a fairly heavy atom, that can only be made inside a red giant star. When the red giant star has finished making copper and moved on to heavier kinds of atoms, eventually it explodes into a supernova and shoots out the copper atoms along with lots of other kinds of atoms.

All of the copper in the universe comes from this process. Copper came to Earth when the Earth first formed out of a nebula cloud. All animals and most plants need copper in order to make some of their enzymes.


Because copper atoms have only one electron in their outer shell, like silver and gold, it's a kind of metal, and it's very easy for copper to share electrons with other atoms to make bigger molecules. Copper atoms can combine with each other to make pure copper, or they can combine with oxygen to make copper oxide (like rust, only with copper instead of iron).

Starting around 3000 BC, people all over the world began to mix copper with tin to make bronze. They found copper by digging mines; there were copper mines on pretty much every continent, and people made bronze everywhere but North America and Australia.

But copper is even more important to us today. Copper makes it particularly easy for electrons to move from one atom to the next, and that makes copper a good metal for moving electricity from one place to another. We use copper wire inside electric cords to move electricity from the wall to your computer, and inside telephone cords to move electricity from your land-line telephone to your friend's telephone to carry the sound of your voice.

Learn by doing - Copper Saucepans and Conductivity

Bibliography and further reading:

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Professor Carr

Karen Eva Carr, PhD.
Assoc. Professor Emerita, History
Portland State University

Professor Carr holds a B.A. with high honors from Cornell University in classics and archaeology, and her M.A. and PhD. from the University of Michigan in Classical Art and Archaeology. She has excavated in Scotland, Cyprus, Greece, Israel, and Tunisia, and she has been teaching history to university students for a very long time.

Professor Carr's PSU page

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