Water Break

Here's a way that you can break the compound water into its elements - hydrogen and oxygen - using electricity.

What you'll need:
2 6-8" pieces of insulated copper hookup wire
4 alligator clips
Wire strippers
Water
Small glass or jar (not made of metal!)
Two pencil "leads" (for mechanical pencils, they're really made of carbon)
Tape
9-V battery

First you'll need to put together the wires; you'll probably need an adult to help with this step. Cut the wire to the length indicated, then strip about 1/2" of insulation from each end. Connect an alligator clip to each end.

Put about 2" of water into the glass or jar. Stand the pencil leads up into the water about 1" apart. The tops should extend above the rim of the glass. Tape the leads to the sides of the jar. Clip one end of each wire to the top of each lead. They break easily, so be careful. Connect the other ends to the battery terminals. There is now be a path for the electricity to flow from one battery terminal, down the wire to the lead, through the water to the other lead, up the other wire, and back through the battery.

Watch the leads carefully. After a few minutes, you should see bubbles forming. They are not filled with air. The bubbles around one lead are hydrogen gas; the bubbles around the other are oxygen. You have successfully split the compound water into its two elements!

When you're done, just unhook the wires from the battery and take everything apart. Throw the water away and wash the glass.

Elements, Compounds, and PB&J Sandwiches

You hear the words "element" and "compound", "atoms" and "molecules", but do you know how they are related? Well, Dr. B is here to tell you, using the analogy of a peanut butter-and-jelly sandwich. Let me explain...

Elements are the basic building blocks of matter. Elements are composed of tiny, tiny atoms. Compounds are combinations of elements made up of very, very small molecules. Picture a jar of peanut butter, a jar of jelly, and a loaf of bread sitting on the kitchen counter. Is this a PB&J sandwich? No, not yet. But you can use these "elements" to create a "compound", a delicious PB&J sandwich. Get two slices of bread, spread a little peanut butter on one and a little jelly on the other, put them together, and presto! - a peanut butter-and-jelly sandwich:

In the same way, cadium (gray balls) and sulfur (yellow balls), which are two elements, can be combined to make the compound cadmium sulfide, which is used in photocells:

In a similar way, you can combine:

• the elements hydrogen and oxygen to make water, or
• the elements sodium and chlorine to make table salt, or
• the elements carbon, hydrogen, and oxygen to make sugar, or
• the elements carbon, hydrogen, oxygen, and nitrogen to make ibuprofen, or
• other elements to make thousands and thousands of compounds

So where do atoms and molecules come in? Atoms are simply the smallest bits of an element that are still recognizable as that element, and molecules are the tiniest bits of a compound that are still recognizable as that compound. You can have a whole loaf of bread slices, and you can divide the loaf into half, then into half again, and so on. Eventually you come to just a single slice of bread. To make it any smaller, you'd have to cut the bread, but then it's not a slice any more - it's just part of a slice. If you could keep dividing an iron nail in the same way, after a long time, you'd come down to just a single iron atom.

In a similar way, you could start separating an enormous pile of PB&J sandwiches, but sooner or later, you'd end up with one sandwich, and you couldn't divide any more without cutting it. You can have a whole tankful of methane (natural gas), a compound of carbon and hydrogen, but after dividing and dividing, eventually you'd get to one methane molecule.

Is this discussion making you hungry? Maybe you want to go make a sandwich for yourself (but check with an adult first!)!