For example, if you are looking at a water molecule, you would write out O, H, and H.

The water molecule breaks this general trend since the oxygen atom (the most electronegative atom in the molecule) is the center atom. Carbon dioxide is an example of a molecule that follows the trend of center atoms being less electronegative. In this case, carbon is the center atom.

In a water molecule, add a single bond from the oxygen to both hydrogens. The hydrogens are not bonded to each other.

Oxygen has 2 lone pair electrons. This means they are not used for bonding, but stay attached to the oxygen.

Since electrons are more attracted to oxygen than hydrogen, they tend to congregate on that end of the molecule. That gives the oxygen a negative charge and the hydrogens a positive charge, creating a dipole. Thus, water is polar.

Many nonpolar solvents fall into the category of volatile organic compounds (VOCs) and are quite dangerous. Be careful when heating them, and always wear a mask and gloves. For example, you could put vegetable oil into the second container. It is not volatile, but still acts as a nonpolar solvent. Acetone is also relatively safe organic solvent, but you should still keep it away from fire and wear your mask and gloves. Acetone is a volatile compound.

For example, you could put 20 mL of isopropyl alcohol into each beaker.

There is no need to heat when testing isopropyl alcohol. Stirring is sufficient. If heating, use a hot plate and heat slowly. Do not heat organic solvents with a flame.

Once both beakers settle, you will notice that the isopropyl alcohol dissolved completely in the water. However, there will be 2 distinct layers where the alcohol separated from the vegetable oil in the second beaker. This shows that isopropyl alcohol is polar.

For example, if you have a running stream of water, a magnet will cause the stream to bend away from the magnet. This shows a clear interaction.

Never put metals, flammables, or explosives into a microwave. If you put water in the microwave, you will notice that it gets hot. It is polar. If you try putting baby oil in the microwave, you will notice that the microwave doesn’t seem to heat it very well. It is nonpolar.

When the microwave comes on, the substance will be subjected to radiation. If it is a polar substance, the radiation will make the molecules spin (though this will not be visible). If the substance is nonpolar, the microwaves will have little effect.