Molecules and Compounds

Molecules and compounds are two types of chemical species. Here is a look at the difference between a molecule and a compound.

From your About Chemistry Guide, these are structures (gifs) for all of the molecules from articles and facts on the About Chemistry website. Many supplemental structures are available, too. Additions are made to the archive regularly.

Functional groups are groups of atoms found within molecules that are involved in the chemical reactions characteristic of those molecules. Functional groups can pertain to any molecules, but you will usually hear about them in the context of organic chemistry.

This is an alphabetical list of alloys grouped according to the base metal of the alloy.

This is an alphabetical list of organic compound names and formulas.

Molecules don't always have long alphabet-soup names. Chemists have a sense of humor. Sometimes molecules have amusing names. Here are some examples of molecules with funny, strange, or silly names.

List of inorganic chemical compounds.

Many molecules are identified by a number following a CAS prefix. What are these CAS numbers and what do they mean?

This photo gallery showcases a variety of chemicals and compounds so that you can see what they look like.

Water is the most abundant molecule on the Earth's surface and one of the most important molecules to study in chemistry. Here's a look at water chemistry.

Many molecules are diatomic. Here's a look the shape or geometry of diatomic molecules.

Hot ice or sodium acetate is an interesting chemical that you can make yourself and cause to crystallize on command to resemble water ice or to form crystalline towers. Here's a collection of answers to common questions about hot ice and solutions to common problems making hot ice.

These are the structures for the twenty natural amino acids, plus the general structure for an amino acid.

Learn what anabolic steroids are, how they can enhance athletic performance, and what risks are associated with using performance enhancing drugs.

Carbohydrates or saccharides are the most abundant class of biomolecules. Carbohydrates are used to store energy, though they serve other important functions as well. This is an overview of carbohydrate chemistry, including a look at the types of carbohydrates, their functions, and carbohydrate classification.

See the chemical structures of chemical weapons and warfare agents and learn a little about their uses.

Molecular compounds or covalent compounds are those in which the elements share electrons via covalent bonds. The only type of molecular compound a chemistry student is expected to be able to name is a binary covalent compound. Here is a look at the nomenclature rules for molecular compounds, plus some examples of how to name the compounds.

This is a list of diatomic molecules.

This is a list of common food additives and a description of their uses.

Here are the names and formulas of some of the common acids and bases. Learn how to apply prefixes and suffixes to name the acids and bases.

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are added to many foods to prevent fat spoilage. This article describes what BHA and BHT are, what they do, and how they do it. There is a fairly lengthy list of references because there is controversy over the health effects of BHA, BHT, and other additives.

Lycopene is the red pigment in tomatoes and several fruits. Find out more about how this antioxidant protects against cancer and heart disease.

This ten question multiple-choice quiz will test your understanding of the types of chemical bonds, how electrons are transferred between elements in a compound, and how compounds form.

Learn about the chemical and biological properties of caffeine, the methylxanthine stimulant found in coffee and other foods.

Part I: Carbon Chemistry and Diamond Crystal Structure. Part II: Properties and Types of Diamonds. There are also links to learn about carbon allotropes, diamond mining, diamonds as gemstones, and geology.

The primary methylxanthine in chocolate is theobromine, a molecule similar to caffeine. See the structure of theobromine and read about its chemistry, effects on people and animals, and uses. There are links to chocolate history and chemical research, veterinary advice for theobromine poisoning, and related resources.

Learn what cocaine or coke is, why people take cocaine, how it's made, and what risks are associated with using cocaine.

Learn what crystal meth is, why people take crystal meth, how it's made, and what risks are associated with using methamphetamine.

See the molecular structures of common drugs, including drugs of abuse. Photos of the drugs themselves are also included.

Dry ice is solid carbon dioxide. Here are some facts about dry ice that can help keep you safe when working with it, plus are just fun to know.

These are the names and structures of important organic functional groups containing nitrogen or oxygen. Learn 'em, live 'em, love 'em!

Do you think chemical weapons smell terrible? You might be surprised to learn many are odorless or smell pleasant.

Find out how sunscreen works, what an SPF rating means, the difference between sunscreen and sunblock, and how to protect yourself from both UV-A and UV-B radiation.

Learn how to synthesize aspirin, acetylsalicylic acid, from salicyclic acid. Get information about the history of aspirin, the effects of salicylates, and see the structures of the reactants.

Molecular geometry is the three-dimensional arrangement of atoms within a molecule. Here's an introduction to molecular geometry with instructions for how to predict configuration and a table of VSEPR geometries.

Learn to distinguish between ionic and covalent bonds, and determine whether a bond will be polar or nonpolar.

Liquid nitrogen is nitrogen that is cold enough to exist in liquid form. It is used for many cooling and cryogenic applications. Here are some liquid nitrogen facts and information about handling liquid nitrogen safely.

Do you know the difference between a mixture and a compound? Combine iron and sulfur to make a mixture and then react them to form a chemical compound.

Learn what marijuana and THC are, why people use marijuana, where it comes from, and what risks are associated with using marijuana.

Learn how molecules, moles, and Avogadro's number relate to each other. This is a good introduction to the study of compounds and stoichiometry.

Here's a collection of molecules that have strange or silly names. There are lots of molecules with weird names, so this list will grow and grow.

Monomers are the building blocks of more complex molecules, called polymers. Polymers consist of repeating molecular units which usually are joined by covalent bonds. Here is a closer look at the chemistry of monomers and polymers.

Take this multiple choice quiz to test your understanding of the states of matter.

This article describes the four levels of protein and polypeptide structure, with examples and links for additional reading.

Learn about ricin and RCA, the two potent toxins from the castor bean plant. Information is provided about the action, symptoms, and treatment of ricin and RCA poisoning.

Learn about the history of Silly Putty, how it works, how to make your own, and what you can do to explore the interesting properties of this viscoelastic liquid.

Here are answers to common questions about snowflakes. Learn how snow forms, what shapes snowflakes take, why snow crystals are symmetrical, whether no two snowflakes really are alike, and why snow looks white!

This is a table of the solubility product constants for some common ions in aqueous solution at 25 degrees Celsius.

See the molecular structures of steroids.

This is a collection of molecular structures of the vitamins.

Are you wondering what makes a chemical a chemical? Here's the answer to this frequently asked chemistry question.

Do you know what dry ice is? Learn about dry ice and find fun projects that use dry ice.

I'll give you a hint: it isn't styrofoam! The world's lightest solid resembles a sort of solid smoke, with a density of only 19 grams per liter.

How poisonous something is depends a lot on how it's administered and a several other factors, but this list will give you a general look at some of the most toxic substances known to man.

There are some man-made chemicals with a stench well beyond the gentle perfume of dirty gym socks and skunk spray. Do you know the names of these super-stinkers?

Did you know there are sweeteners that are 200,000 times sweeter than table sugar? Take a look at this list to find out how your favorite sweetener rates.

You probably know that lead is toxic, but do you know what makes it poisonous? Here's an explanation of what lead does in your body that makes it such a health hazard.

Learn about hydrogen bonding and density to understand why ice floats on water.

Salt and sodium content are related, but are not the same. Learn about the difference between salt and the sodium in sodium chloride and how to calculate sodium levels in salt.

This is a collection of photographs of various chemicals that might be found in a chemistry laboratory.

You may have wondered what is meant by the term "pure substance". Here's a look at what a pure substance is and how you can tell if a substance is pure or not.

Do you have questions about alum? Find out what alum is and the uses of alum.

Here is what muriatic acid is, where you can find it, and its uses.

Here's a look at what borax is, facts about borax and how you can get borax.