Copper

Copper — page 1 — Introduction Has anyone ever offered you a penny for your thoughts This small coin is made mostly of copper a metal that people have used since our early ancestors found shiny pieces of it among riverbed stones and sometimes in the ashes of their fires When humans began chipping rocks into tools and arrowheads they also used pieces of copper for tools Copper was softer than many rocks but still useful Metallurgy is the study of metals and their chemistry It is also the sci(cid:173) ence that deals with extracting metals from their ores of purifying or alloying mixing metals and of creating useful objects from metals Metallurgy probably began with the early use of copper Copper melts at a lower temperature than iron so copper was probably the first metal our ancestors learned to smelt out of ore in simple kilns and bonfires Copper ores are often colored making them easier to recognize than ores of most other metals People eventually learned that molten copper also combines with other metals such as zinc tin or nickel to make harder alloys which can be used for making weapons and farming and construction tools Copper is also present in plants and makes up a tiny but important part of our food and our bodies Copper silver and gold are called the coinage metals because they are used for making coins Coins often had an image of a god or ruler stamped onto one side Modern coins from Canada and Great Britain

Copper — page 2 — Introduction Copper has always been found in nuggets in streambeds above Copper can also be mined from rock in Earth's crust where it is combined with other elements elements in copper ores The heat of a simple kiln or a bonfire is enough to melt copper out of ore unlike some other metals that melt at a higher temperature show the face of Queen Elizabeth II with these words in Latin D G Regina or Queen by Grace of God The ancient Greeks associated copper with Aphrodite goddess of love and wife of Hephaestus the Greek god of fire and metalworking Copper coins are still associated with reverent thoughts People throw pennies into fountains while making a wish Some native North Americans when traveling by ship even throw a penny into the water as their journey begins 5

Copper — page 3 — Chapter Onee The Element Copper The element copper is a familiar part of life in the developed world Copper's chemical symbol Cu comes from the Latin word cyprium which was later shortened to cuprum meaning from the island of Cyprus Copper found in its pure state in nature called native copper has been known since ancient times Tools made of copper alloys mixtures of copper with other elements have been used since the beginning of the Bronze Age around 4000 BC In its pure form copper is used in electrical wire plumbing pipe and jewelry Pure copper is a shiny metal with a red-orange color The surface of pure copper tarnishes very slowly when exposed to air and water but this thin green or brown patina does not crumble like rusty iron A patina is a film that forms nat(cid:173) urally on copper or its alloys as a result of oxidation Copper is a relatively soft metal that can be bent beaten or cast into useful shapes It is even more useful when it is combined with other elements usually tin or zinc to make bronze or brass alloys Bronze and brass are used to make many tools screws and other hardware that resist corrosion or decay Atoms Elements and Compounds Everything you can see in the world and nearly everything in the universe is made up of elements Some objects are pure with one kind

Copper — page 4 — The Element Coppe of element only Some are compounds with different elements bonded chemically sticking together as if they were glued together in different arrangements and with glues of different strengths How small a piece can you have of an object If you started with a trumpet you could see that it has some brass metal parts and some steel parts The smallest piece of brass you could cut would have copper and zinc which were originally melted together at a high temperature You could use chemical reactions to separate out the copper The smallest por(cid:173) tion that you can have of an element is called an atom which is far too small to see with the microscope you might use in school Atoms of cop(cid:173) per are so tiny that about thirty-five million of them side by side would make a line only 0 4 inch 1 centimeter long One atom would be the smallest piece of copper you could ever have Inside that atom are even smaller pieces called subatomic particles Inside the Atom Atoms are made of three main kinds of subatomic particles At the center of the atom the nucleus is a dense core of protons which carry a posi(cid:173) tive electrical charge and neutrons which have no charge The nucleus is a small part of the atom it's like a marble in the center of a football stadium But the nucleus contains nearly all the mass of the atom Copper has twenty-nine protons in its nucleus That is how the element is identi(cid:173) fied Any atom anywhere in the universe with twenty-nine protons in its nucleus is an atom of the element copper Around the atom's nucleus the electrons occupy overlapping layers called shells Electrons have a negative electrical charge and are attracted to the protons in the nucleus The negative and positive elec(cid:173) trical charges of the atom are balanced and the number of electrons and protons are equal An atom of copper has twenty-nine protons and twenty-nine electrons 7

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