Binary molecular compounds are compounds that consist of exactly two nonmetal elements. Examples include HF, NO2, and P2O5. Naming binary molecular compounds is really quite easy. The first element is given its element name; the second is given its root (hydr, bor, carb, ox, fluor, etc.) followed by ide.
Element Roots | |||||
---|---|---|---|---|---|
H | |||||
hydrogen | |||||
B | C | N | O | F | |
boron | carbon | nitrogen | oxygen | fluorine | |
Si | P | S | Cl | ||
silicon | phosphorus | sulfur | chlorine | ||
As | Se | Br | |||
arsenic | selenium | bromine | |||
Te | I | ||||
tellurium | iodine |
For example, HCl is hydrogen chloride, and H2Se is hydrogen selenide.
To be unambiguous (N2O, NO, NO2, and N2O4 all exist), we use Greek prefixes to explicitly indicate how many of each element are present. You need to memorize at least the first six Greek prefixes:
1=mono | 2=di | 3=tri | 4=tetra | 5=penta | 6=hexa |
Beyond that, it's simply a matter of remembering the following four rules to make the names a little more readable:
Examples include:
XnYm | n-preX-name m-preY-ide | |
N2S | dinitrogen monosulfide | (standard) |
N2O3 | dinitrogen trioxide | (standard) |
CO2 | carbon dioxide | Rule 1 |
HCl | hydrogen chloride | Rule 2 |
CO | carbon monoxide | Rule 3 |
N2O4 | dinitrogen tetroxide | Rule 4 |
In summary, memorize the 15 nonmetal element names and symbols, memorize the first 6 prefixes, learn the four rules, and practice.
YOU CAN DO IT!