Hey, I got you a present!  Can you guess what it is?  It's carbon!  Are you excited?  Oh, you don't know what that is?  Well, it could be the best present you've ever received . . . or it could be the worst.  See, carbon comes in many different forms.  Depending on how it is put together, one element can make many different gifts.  Some are good, but some are terrible.


Well, I can tell you what I did not get you.  I did not get you a bunch of the same gas that you just made inside your cells as you read this sentence.  Carbon dioxide is a gas that you breathe out.  It makes up less than 1% of the atmosphere.  It is made when carbon bonds with the oxygen we breathe in.  It also makes a warm blanket around our world that raises our heat.  This is bad for us, since plants need this gas to make food.  Maybe I will give this gas to a tree. 


It is not Halloween, so I did not get you something that makes stuff that looks like smoke.  When carbon dioxide is frozen into a solid, it makes dry ice.  When you put this in water, it will let off smoke that crawls like a snake and looks really cool.  This makes it great for mailing things that need to be kept cold for long distances.  Dry ice will keep something cold, and as it "melts" it turns into smoke instead of messy water.  Another reason I did not get dry ice for you is because when you opened the box, the dry ice would be so cold, it would burn your hands!  Dry ice is very, very, very cold.  Maybe I will give it to a polar bear.

Dry Ice is spooky.


I did not get you a really nice jewel because, well, I do not have enough money.  When carbon is packed together really tightly, it can make the hardest thing we know.  A diamond is a clear stone that costs a lot of money and is made when carbon crystallizes.  Yes, diamonds make nice jewelry, but we also use diamonds to polish tools and make them sharp.  Maybe I got you a sharp tool!  Wait.  That would not be made out of carbon.

See, good things do come in small packages.


There's another form of carbon that is not packed together so tightly.  It's black and it flakes off on anything you press it against.  Graphite is what's inside your pencil, and it is also made of carbon.  It is what's left over from the very old bodies of dead plants and animals.  Wait a second, did I buy you a bunch of old dead plants and animals.  Why, yes I did.  It's a pencil!  This stuff can also be used to make steel stronger, but I think you should use this pencil to write about science.

Not all pencils can be No. 1, this one is a No. 2.


Carbon comes in many forms.  Some of them could make very bad gifts, like the gas that your cells make or dry ice.  One could make a very pretty gift that costs a lot of money in the form of diamond.  And one could be very useful, like a pencil.  Is your gift disappointing after hearing that carbon can make diamonds?  Well, I could give you this other kind of carbon instead . . . It's a lump of coal!  You like the pencil now?  Great!  You are welcome.



References:

How Stuff Works.  "How does dry ice work?"  Discovery, 2009.  <http://science.howstuffworks.com/innovation/science-questions/question264.htm>

History for Kids.  "Carbon Dioxide"  Kidipede, 2010.  <http://scienceforkids.kidipede.com/chemistry/atoms/carbondioxide.htm>

Kids Science.  "Diamond Facts"  Kids Science, 2011.  <http://www.sciencekids.co.nz/sciencefacts/chemistry/diamond.html>