Why are you able to put your hand through water but not through a table?  Why can you stick your finger into Jell-O which you can't see through but you can't stick it through glass, which you can see through?  And why am I so bad at tennis?  Oh, sorry.  More on that in a bit.  Some things in this world just will not let your hand through, no matter how clear they are.  I think it's time to take a closer look.

I can't put my hand through the glass or the sharks, but I can put my hand through the water.


Tables, rocks, bones, walls, metal, trees, baseballs.  How are they all the same?  Solids are things that keep their shape because their building blocks are locked together.  You cannot put your hand through them.  Solids are different than water because they hold still.  They are different from gas because they are not floating around everywhere.  Unless they are bees . . .  Bees are solid and you should not try to stick your finger through them.  They will stick you right back.

Bees are nice to look at but not nice to touch.


Man, am I ever bad at tennis.  Man, am I ever bad at tennis.  Whoops, I guess I already said that.  Repeating means to do the same thing over again.  If you look at a fence, or my tennis racquet, you will see the same thing repeated many times.  There are lots of diamonds or squares in columns and rows.  If you look up close at a solid, you will see the same thing.  The building blocks that make it up keep repeating.  This helps hold it together and keep your finger out.  If you look up close at my tennis racquet, you will see lots of strings going up and down, up and down.  You will also see me repeating my moves on the tennis court, hitting the ball again and again and again and again, but the ball never seems to go where I want it to . . . RRG!


Hold on.  I need to let out some frustration.


GRR        GRR        GRR        GRR        GRR
        RRG        RRG        RRG        RRG


A pattern is a design or shape that repeats over and over, just like when I got angry up there.  You will see patterns everywhere: on plates, on wallpaper, on shirts, and on solids up close.  It's this pattern that makes the solid strong and will not let your finger through.  But wait . . . you can stick your finger through a fence and a tennis racquet.  But you can't stick your finger through a solid.  I guess we'll have to look even closer. 

I can stick my finger through this fence but not my hand. What's up with that?


A screen door.  A chain link fence.  My tennis racquet.  If we take a lot of shapes that repeat and stack them on top of each other, then we have the same shape repeating left, right, up and down.  This is a lattice.  A lattice is when the building blocks of a solid repeat in a pattern in all directions.  All of the building blocks in solids are crossed over each other so much that they will not let anything through.  Because there's a lattice on the surface of a solid, we can draw lines between each building block to make a type of 3D-looking fence.  This isn't easy to see through, and it's even harder to get through.

A bee's honeycomb makes a delicious lattice. Do bees eat honey on toast?


What's that about my tennis racquet?  The pattern is broken?  Let's see . . . string, hole, string, hole, string, hole, HOLE?  I'm missing a string!  The lattice is broken!  No wonder I'm so bad at tennis.  Thank you!  Solids don't have this problem.  They have lots of lattices.  Even if one breaks, the others won't let your finger pass through.  If you look at a rock or a wall or a ball or a bee, you'll always discover the same thing: a repeating pattern.  This makes layers of lattices that are so tightly fit together that they won't let anything through.  Now I'm not going to let this ball through!  Swing!  Miss!  Guess I'd better repeat my practice some more.



References:

Chem 4 Kids.  "Solid Basics"  Chem 4 Kids, 2012.  <http://www.chem4kids.com/files/matter_solid.html>

Ducksters.  "Crystals"  Ducksters, 2013.  <http://www.ducksters.com/science/crystals.php>