Chemical compounds are formed when elements are joined by chemical bonds. These bonds are so strong that the compound behaves like a single substance. Compounds have their own properties that are unique from the elements they are made of. A compound is a type of molecule with more than one element. You can go here to learn more about molecules and compounds.
How Compounds are Named
Chemists have a specific way of naming compounds. It is a standard method of naming compounds that is used by scientists around the world. The name is built from the elements and the construction of the molecule.
Basic Naming Convention
First we'll cover how to name molecules with two elements (binary compounds). The name of a compound with two elements has two words.
To get the first word we use the name of the first element, or the element to the left of the formula. To get the second word we use the name of the second element and change the suffix to "ide" at the end of the word.
Some examples of adding the "ide":
O = oxygen = oxide
Cl = chlorine = chloride
Br = bromine = bromide
F = fluorine = fluoride
In cases where there is more than one atom (for example there are two oxygen atoms in CO2) you add a prefix to the start of the element based on the number of atoms. Here is a list of the prefixes used:
When there are two elements in a compound, which element goes first in the name?
If the compound is made of a metal element and a nonmetal element, then the metal element is first. If there are two nonmetal elements, then the first name is the element to the left side of the periodic table.
Examples:
In a compound that contains iron and fluoride, the metal (iron) would go first.
In a compound that contains carbon and oxygen the element to the left on the periodic table (carbon) would go first.
More Complex Naming Rules
See below for some of the more complex naming rules.
Naming Metal-Nonmetal Compounds
If one of the two compounds is a metal, then the naming convention changes a bit. Using the stock method, a roman numeral is used after the metal to indicate which ion is using the charge.
Examples:
Ag2Cl2 = silver (II) dichloride
FeF3 = iron (III) fluoride
Naming Polyatomic Compounds
Polyatomic compounds use a different suffix. Most of them end in "-ate" or "-ite". There are a few exceptions that end in "-ide" including hydroxide, peroxide, and cyanide.
