Molecules

An atom of carbon can bond to 4 hydrogen atoms. A molecule consisting of one carbon atom and 4 hydrogen atoms forms methane, the simplest hydrocarbon. The bonds are covalent bonds, meaning electrons are shared between the atoms. We can write methane a couple different ways:

   H
   |
H--C--H
   |
   H

The figure on the left shows all the atoms and the bonds that join them together. This is very handy for simple molecules like methane, but for larger molecules it could become tedious to write out all those letters. The figure on the right is a condensed formula. It specifies that there is one carbon atom and that it has 4 hydrogen atoms bonded to it. Two more ways we can show molecules is using ball-and-stick models and space-filling models:

One thing we can see from the models is that the bonds aren't in a nice square grid like in the flat figure above. They're actually arranged in the shape of a tetrahedron. This keeps the bonds as far apart from each other as possible, and it keeps them evenly spaced.