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Molecules and Compounds

Find chemical structures, articles, and other information about molecules and compounds.
  1. Chemical Composition (24)
  2. Chemical Weapons (16)
  3. Facts & Structures (100)
  4. Gases (28)
  5. Metals & Alloys (104)
  6. Water Chemistry (98)

What Is the Difference between a Molecule and a Compound?
Molecules and compounds are two types of chemical species. Here is a look at the difference between a molecule and a compound.

Chemical Structures Archive
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.

What Is a Molecule?
The terms molecule, compound, and atom can be confusing! Here's an explanation of what a molecule is with some examples of common molecules.

Functional Groups
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.

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

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

Ionic Compound Properties
Here are the properties shared by the ionic compounds.

Covalent Compound or Molecular Compound Properties
These are properties of covalent compounds, also known as molecular compounds.

Molecules with Strange or Silly Names
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.

Compounds - Inorganic Chemicals
List of inorganic chemical compounds.

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

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

Water Chemistry
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.

What Shape Are Diatomic Molecules?
Many molecules are diatomic. Here's a look the shape or geometry of diatomic molecules.

Hot Ice Help
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.

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

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

Carbohydrates
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.

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

Covalent or Molecular Compound Nomenclature
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.

Diatomic Molecules
This is a list of diatomic molecules.

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

Formulas of Common Acids & Bases
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.

BHA and BHT - Food Preservative Chemistry
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.

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

Bonds & Compounds Quiz
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.

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

Chemistry of Diamond
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.

Chemistry of Theobromine
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.

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

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

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

Dry Ice Facts
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.

Functional Groups - Organic Chemistry Essentials
These are the names and structures of important organic functional groups containing nitrogen or oxygen. Learn 'em, live 'em, love 'em!

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

How Sunscreen Works
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.

How to Make Aspirin - Acetylsalicylic Acid
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.

Introduction to Molecular Geometry
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.

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

Liquid Nitrogen Facts
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.

Make a Mixture and a Compound from Iron and Sulfur
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.

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

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

Molecules with Strange Names
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 and Polymers
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.

Phases & Phase Changes Quiz
Take this multiple choice quiz to test your understanding of the states of matter.

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

Ricin and RCA - Castor Bean Toxins
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.

Silly Putty Chemistry
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.

Snowflake Chemistry
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!

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

Steroid Molecular Structures
See the molecular structures of steroids.

Vitamin Chemical Structures
This is a collection of molecular structures of the vitamins.

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

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

What Is the Lightest or Least Dense Solid?
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.

What Is the Most Poisonous Chemical Compound?
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.

What Is the Smelliest Chemical?
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?

What Is the Sweetest Compound?
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.

What Makes Lead Poisonous?
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.

Why Does Ice Float?
Learn about hydrogen bonding and density to understand why ice floats on water.

Sodium Versus Salt
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.

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

What Is a Pure Substance?
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.

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

What Is Muriatic Acid?
Here is what muriatic acid is, where you can find it, and its uses.

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

Table of Electrical Resistivity and Conductivity
This is a table of electrical resistivity and electrical conductivity of several materials.

Elements in the Body PDF
Elements in the Body PDF

10 Molecules with Funny or Weird Names
Meet 10 molecules with funny or downright weird names.

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