A molecule is a small particle. It is usually the smallest particle of an element, or a compound. A chemical molecule is made of atoms that are the same; for example, an oxygen molecule is made of only oxygen atoms, while a water molecule is made up of only water molecules, which are the smallest units of the compound of hydrogen and oxygen.
Organic versus inorganic in chemistry
In chemistry, the word organic means carbon. An inorganic molecule contains no carbon. A molecule is also considered to be inorganic if it does not have a biological origin. Most living things on Earth contain organic molecules, and are therefore classified as being made of organic molecules containing carbon. Some things such as minerals contain carbon but are considered to be inorganic, because they are not produced by a living organism and are therefore not from a biological origin. An example of this is a diamond. A diamond is made of pure carbon. Though carbon is dark colored, when compressed over time, it turns to a clear diamond. This is still a form of carbon; in fact, it is one of the purest forms. A diamond is considered to be made of inorganic molecules because it was not produced by a living organism.
Organic molecules are those made by living systems. These molecules are usually constructed of rings and chains of carbon atoms along with other elements, such as nitrogen, hydrogen and oxygen. Organic molecules have some things in common. Organic compounds dissolve organic solvents such as ethyl alcohol. They can form stable covalent bonds with each other. Therefore, they can form a variety of different structures. These structures are carbon compounds. Carbon compounds are not as water soluble as inorganic salts. Organic molecules come in many different forms. Some of these are polymers, biomolecules, aromatic compounds, hydrocarbons, buckyballs and aliphatic compounds.
Four types of organic molecules
There are four different types of organic molecules: carbohydrates, lipids, proteins and nucleic acids. Carbohydrates have a ratio of one carbon molecule to one water molecule. They are hydrated carbon, hence the name carbohydrate. Proteins are a polymer made of smaller parts (monomers) called amino acids. Each amino acid is made with a base amino group, an acidic carboxyl group, and a hydrogen atom. Each of these is connected to one carbon atom, called an alpha carbon. Peptides link the amino acids together. Lipids are a class of organic molecule that is not attracted to water. The term for this is hydrophobic. There are four major types of lipids: fats, phospholipids, waxes and steroids. Nucleic acids are a form of organic molecule made from nucleotides. Nucleic acid is a polymer. Each of its nucleotides contains one pentose sugar, some phosphate groups and have one of five varying nitrogen bases.