What are Molecules? | Types, Definition, Structure, Function & Facts

What are Molecules?

Whenever two atoms come together, they form a molecule. Everything around you is made up of molecules. This includes you! You are literally made up of trillions upon trillions of different types of molecules.

Compounds

When atoms of different types of elements combine, they form molecules called compounds. Water is made up of molecules made up of 2 hydrogen atoms and 1 oxygen atom. That’s why it’s called H2O. Water will always have twice as many hydrogen atoms as oxygen atoms.

Molecular Formula

There are just over 100 types of atoms, but there are millions upon millions of different types of substances. Indeed, they are all made up of different types of molecules. Molecules are not only composed of different types of atoms, but also in different proportions. As in the water example above, a water molecule has 2 hydrogen atoms and 1 oxygen atom. It is written as H2O.

Other examples are carbon dioxide (C02), ammonia (NH3), and sugar or glucose (C6H12O6). Some formulas can be quite lengthy and complex.

Let’s look for the sugar molecule:

C₆ – 6 carbons atoms
H₁₂ – 12 hydrogen atoms
O₆ – 6 oxygen atoms

It takes specific atoms in this specific number to make a sugar molecule.

Bonds

Molecules and compounds are held together by forces called chemical bonds. There are two main types of bonds that hold most compounds together: covalent bonds and ionic bonds. Some compounds can have both types of bonds.

Two main types of bonds involve electrons. Electrons orbit the atoms in the shell. These shells want to be “full” of electrons. When they are not full, they will try to bond with other atoms to get enough electrons to fill their shells.

Covalent Bonds – Covalent bonds share electrons between atoms. This happens when atoms happen to share their electrons to fill their outer shells.

Ionic Bonds – Ionic bonds are formed when one electron is donated to another. It occurs when one atom gives up an electron to another atom to form an equilibrium and thus form a molecule or a compound.

Fun Facts about Molecules

Oxygen gas is usually molecular O2, but it can also be O3 which we call ozone.

66% of the mass of the human body is made up of oxygen atoms.

Molecules can have different shapes. Some are long spirals while others may be pyramidal.

Organic compounds are compounds that contain carbon.

A perfect diamond is a single molecule made up of carbon atoms.

DNA is a super-long molecule that contains information that uniquely describes each person.