| prefix<\/td>\n | number<\/td>\n<\/tr>\n |
| mono<\/td>\n | 1<\/td>\n<\/tr>\n |
| di<\/td>\n | 2<\/td>\n<\/tr>\n |
| tri<\/td>\n | 3<\/td>\n<\/tr>\n |
| tetra<\/td>\n | 4<\/td>\n<\/tr>\n |
| penta<\/td>\n | 5<\/td>\n<\/tr>\n |
| hexa<\/td>\n | 6<\/td>\n<\/tr>\n |
| hepta<\/td>\n | 7<\/td>\n<\/tr>\n |
| octa<\/td>\n | 8<\/td>\n<\/tr>\n |
| nona<\/td>\n | 9<\/td>\n<\/tr>\n |
| deca<\/td>\n | 10<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Take, for example, dinitrogen pentoxide. The di<\/em> before nitrogen tells us there are two nitrogens; the penta<\/em> before oxide tells us there are five oxygens.\u00a0 Therefore, we have<\/p>\n dinitrogen pentoxide: N2<\/span><\/sub>O5<\/span><\/sub><\/p>\n Going the other way, here is a point to mind: The prefix mono<\/em> is rarely used<\/strong>. For example:<\/p>\n SF6\u00a0<\/span><\/sub>\u00a0:\u00a0\u00a0sulphur hexafluoride.<\/p>\n Note that we don’t call it mono<\/em>sulphur hexafluoride, even though there is only one sulphur. However, we do call CO carbon monoxide. To my knowledge, mono<\/em> is only used when another related\u00a0compound is more common. In the case of carbon monoxide, we use mono<\/em> to distinguish it from carbon di<\/em>oxide, which of course is more often mentioned. Whatever the reason, the prefix mono<\/em> is seldom used, even when there is only one of that atom.\u00a0 Other examples:<\/p>\n CCl4<\/span><\/sub> : carbon tetrachloride<\/p>\n BF3<\/span><\/sub> : boron trifluoride<\/p>\n Of course, one question that might evolve:\u00a0 “How can I tell if a compound is ionic or covalent?”\u00a0 The simple answer:\u00a0 If the compound is ionic, its name starts with a metal.\u00a0 If it’s covalent, it starts with a nonmetal.\u00a0 I explain how to tell a metal from a nonmetal here<\/a>.<\/p>\n Remember:\u00a0 only covalent compounds use the numeric prefixes<\/strong> in the table above; ionic compounds don’t use them.<\/p>\n Source: Chemistry<\/em>, Charles E. Mortimer, Sixth Edition, Wadsworth, Inc., 1986.<\/p>\n |