How to Name Covalent Compounds

Step-by-Step Guide

1. 1

   Step 1: Name the first element in the compound.

   Molecular formulas are read from left to right, just like English words.
   
   Generally, the first atom (the one on the left of the molecular formula) is also the least-abundant atom in the compound, though there are exceptions.
   
   Write the name of this atom first.
   
   For example, in the molecular formula CF4, Carbon (C) comes first, so we write it first: "Carbon" If you only know the atoms in the molecule and you don't know the molecular formula, don't worry.
   
   In covalent compounds, the element that comes first in this list gets written first in the molecular formula:
   B, Si, C, Sb, As, P, N, H, Te, Se, S, I, Br, Cl, O, F Note that there is one exception: when oxygen is paired with a halogen (a Period 7 element like F, Cl, etc.), the halogen comes first., Next, look at the second atom in the molecule.
   
   Determine how many times it appears in the molecule.
   
   This is the number written in subscript next to it in the molecular formula.
   
   If there is no number next to the second atom, it appears once.
   
   Find the appropriate Greek prefix from the table above and write it next.
   
   In our sample element, CF4, fluorine is the second element and it appears four times.
   
   We'll write the Greek prefix for four, tetra, next, like this: "Carbon tetra-"
   
   Now, simply write the name of the second atom as if it were an anion (negatively-charged ion).
   
   In other words, just stick "-ide" on the end.
   
   For example, oxygen becomes "oxide," chlorine becomes "chloride," and so on.In our sample element, CF4, fluorine is the second element, so we'll write it at the end.
   
   Be sure to add the
   -ide ending, like this: "Carbon tetrafluoride".
   
   Notice that the Greek prefix and the second atom form a single word together.
   
   They are never written as two separate words. , Determine how many times the first atom appears in the molecule.
   
   If you have the molecular formula, this will be the number written in subscript after the first atom.
   
   Again, if there is no number, the first atom appears once.
   
   If the atom does appear more than once, write its Greek prefix at the beginning of the name.
   
   In our sample element, CF4, carbon appears once, so we don't have to do anything.
   
   We wouldn't write "mono" at the beginning.
   
   You only use "mono" for the second atom — never the first. , Congratulations — you're done.
   
   Your compound's name is written in this form: followed by We already know our compound's name:
   Carbon tetrafluoride. , The rules above will serve you well for nearly all normal binary covalent molecules.
   
   However, a few select molecules get special names that are almost always used when they're discussed in scientific settings.
   
   There isn't really any way to predict these — you just have to learn them.
   
   A few examples include:
   H2O is not Hydrogen dioxide.
   
   It's "water." NH3 is not Nitrogen trihydride.
   
   It's "ammonia." CH4 is not Carbon tetrahydride.
   
   It's "methane."
2. 2

   Step 2: Write the Greek prefix for the number of the second atom.

3. 3

   Step 3: Name the second atom and end it with "-ide."

4. 4

   Step 4: Add a Greek prefix at the beginning if there is more than one of the first atom.

5. 5

   Step 5: Put it all together.

6. 6

   Step 6: Know that certain compounds are exceptions to normal naming rules.

Detailed Guide

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