Nomenclature Ionic and Covalent Compounds

Rules for naming ionic compounds The cation (+) is always named first, followed by the anion (-) second. The cation takes its name from the element. So, Na+ is called sodium, or any compound containing Na would start with sodium The anion gets its name from taking the root of the element name and adding “-ide”. So, Cl- becomes chloride. Combine the cation name (#2) and anion name (#3), to create the name of the compound Thus, the compound NaCl is called sodium chloride.

Practice Problems Formula NaCl KI CaS CsBr Li3N MgO Ions Present Name Sodium Chloride Potassium iodide Calcium sulfide Cesium Bromide Lithium nitride Magnesium oxide

Rules for naming ionic compounds that contain transition metals Some transition metals can form more than one type of positive ion. For example, Fe (Iron) can exist as Fe2+ or as Fe3+ so how do we differentiate the two? EASY! We simply look at the charge on the ion, and use that number as a Roman numeral. Then we follow the rules of naming ionic compounds. Therefore if we take Fe2+ and Cl- we will get Iron(II) chloride. (FeCl2) Conversely, if we have Fe3+ and Cl- we end up with Iron(III) chloride. (FeCl3) Tip: If given just the compound, look at the charge from the anion, and neutralize compound with the given cation.

The exceptions Aluminum always has a charge of 3+ (Al3+) Silver always has a charge of 1+ (Ag+) Zinc always has a charge of 2+ (Zn2+) Due to this, there is no need to add the Roman numeral. Therefore, Al2O3 is simply aluminum oxide.

Practice problems Formula FeCl2 FeCl3 CuBr HgS Fe2O3 PbCl2 ZnF2 Cation Present Fe2+ Fe3+ Cu+ Hg2+ Pb2+ Zn2+ Anions Present Cl - Br - S2- O2- F - Name Iron(II) chloride Iron(III) chloride Copper(I) Bromide Mercury(II) Sulfide Iron(III) Oxide Lead(II) chloride Zinc floride

Rules for naming Covalent Compounds The first element in the formula is named first, using the full element The second element is named as if it were an anion. Like the ionic compounds add “-ide” at the end of the word. You must use prefixes to denote the number of atoms presents in the compound The prefix mono is never used for naming the first element. For example, CO is called carbon monoxide, not monocarbon monoxide.

Prefixes Prefix Number indicated Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca Number indicated 1 2 3 4 5 6 7 8 9 10

Practice problems Formula PCl5 N2O N2O4 SF6 SO3 Name Phosphorus pentachloride Dinitrogen monoxide Dinitrogen tetroxide Sulfur hexafluoride Sulfur trioxide

Lets take a look back at DHMO Dihydrogen monoxide Di the prefix for 2 Mono is the prefix for 1 So, 2 hydrogens and 1 oxygen In other words, H2O or water