Bohr model of the helium (He) atom.  He has two protons in the nucleus and two electrons in its single energy level.

From http://bio.winona.edu/berg/Free.htm

This (partial) periodic chart shows incomplete Bohr models (no nucleus).

Here, the energy levels are called "shells." 

The electron cloud model shows electrons moving in a cloud around the nucleus.

From http://bio.winona.edu/berg/Free.htm

In this covalent bond, two H atoms "share" their single electrons, to form a pair of shared electrons.

From http://bio.winona.edu/berg/Free.htm

Three models of a water molecule (polar)

From http://bio.winona.edu/berg/Free.htm

In this space-filling model, glucose (center molecule) is a polar molecule with unequal sharing of electrons.  It dissolves easily in water because the positive regions of a water molecule are attracted to glucose's negative regions and the negative regions of a water molecule are attracted to glucose's positive regions --so they "get along"

From http://bio.winona.edu/berg/Free.htm

Ions, too, "get along" with water just fine!

Click on images to enlarge

Two models of a glucose molecule: structural and space-filling.

From http://bio.winona.edu/berg/Free.htm

A              B

A Structural model of a phospholipid

B Stick figure of a phospholipid

Phospholipid bilayer (a simple model)

Phospholipid bilayer (a current detailed model)