"Chemical Formula Naming Guide Dr C’s Handy Dandy Naming Guide"
Dr. C’s Handy-Dandy Naming Guide Going from a Chemical Formula to a Name (HCl to hydrochoric acid, for example) Side 1 IS THIS COMPOUND A MOLECULE, IONIC COMPOUND, OR ACID? Ionic compounds are made Molecules contain only Acids all start with a hydrogen in with either metals to non-metals nonmetals and DON’T contain their formula and then have some or contain polyatomic ions any polyatomic ions negative ion following 1. Take the formula and break 1. Take the formula and identify 1. Take the formula and break it up it back up into the ions it came the nonmetals. into the H+ ion and the negative from. Ex PCl3 contains phosphorus and anion it came from. Ex NaCl goes to Na+ and Cl- chlorine (two nonmetals) Ex H2SO4 goes to H+ and SO4-2 Ex N2O4 contains nitrogen and Ex H2SO3 goes to H+ and SO3-2 2. Write the name of the first oxygen Ex H2S goes to H+ and S-2 ion (the cation) 2. Write the name of the first 2. Identify the name of the anion Ex Na+ is named “sodium” nonmetal and save a little room in because that decides what the acid’s the front for a Greek prefix later. name will be. 3. Write the name of the Ex PCl3 you should write Ex SO4-2 is called sulfate second ion (the anion) “ phosphorus” Ex SO3-2 is called sulfite Ex Cl- is named “chloride” Ex N2O4 you should write Ex S-2 is called sulfide ” nitrogen” 3. Identify the ending of the anion, 4. Say them both together. 3. Write the name of the second which will tell you how to name the Ex NaCl is “sodium chloride” nonmetal, but change the ending to acid. There are 3 separate rules, “-ide”. Leave a space in front. because there are 3 separate endings BE CAREFULS: Ex PCl3 you should write for anions. 1. Never use any of the Greek “ chloride” 3a. If the anion’s name ends in prefixes (only used for Ex N2O4 you should write “ate” you take the root of that name MOLECULES). If there is “ oxide” and add “-ic acid” for the name. more than one of a cation or 4. Put the Greek prefixes in the Ex H2SO4 is sulfuric acid, because anion, you still just say that spaces front of each nonmetal to SO4-2 is sulfate name once. indicate how many, except you 3b. If the anion’s name ends in Ex CaCl2 is calcium chloride, don’t use “mono” on the first “ite” you take the root of that name NOT calcium dichloride nonmetal. and add “-ous acid” for the name. Ex PCl3 you should write Ex H2SO3 is sulfurous acid because 2. Remember to write the “phosphorus trichloride” (no SO3-2 is sulfite roman numeral for the “mono in front of the phosphorus) 3c. If the anion’s name ends in transition metals that indicates Ex N2O4 you should write “ide” you take the root of that name, their charge. “dinitrogen tetraoxide” start with “hydro-,” put in the root, Ex Fe(OH)3 is iron (III) Greek Prefixes [1-mono] [2-di] and end with “-ic acid” for the name. hydroxide, not just iron [3-tri] [4-tetra] [5-penta] [6-hexa] Ex H2S is hydrosulfuric acid because hydroxide. [7-hepta] [8-octa] [9-nona] [10- S-2 is sulfide. deca] (memorize these) BE CAREFULS: BE CAREFULS: 1. Don’t let any prefixes you see in 1. If you see three or more the anions confuse you; they have nonmetals, you probably have an NOTHING to do with naming ionic compound with a polyatomic Ex HClO is hypochlorous acid ion you don’t recognize. because ClO- is hypochlorite Ex (NH4)2CO3 is the IONIC 2. Remember the tricks to naming COMPOUND ammonium acids carbonate. A.I ATE at the cafeteria and said IC 2. Don’t let the Greek prefix in the B.The physician said I had ION “dichromate” fool you. It’s appendicitis (appendic ITE – OUS) still done as an ionic compound. C. I’d hide Rick (IDE HYDR O IC) Dr. C’s Handy-Dandy Naming Guide Side Going from a Name to a Chemical Formula (silver nitrate to AgNO3, for example) 2 IS THIS COMPOUND A MOLECULE, IONIC COMPOUND, OR ACID? Ionic compounds are made Molecules contain only Acids all start with a hydrogen in with either metals to non-metals nonmetals and DON’T contain their formula and then have some or contain polyatomic ions any polyatomic ions negative ion following 1. Take the name and write 1. Take the name and identify the 1. Take the name and write down an down each of the ions with two nonmetals. H+ and the name of the anion the acid their charges Ex dinitrogen trioxide has nitrogen came from. You need three different Ex calcium bromide goes to and oxygen within it. rules for the three different acid names. Ca+2 and Br- 2. Write the symbol of each 1a. acids ending in “-ic acid” came 2. Use enough of each ion so nonmetal and use the Greek prefix from “-ate” anions that the total charge will add up to give you the subscript for each Ex nitric acid yields H+ and NO3-, to zero by inspection or the Ex dinitrogen trioxide has “N” and hyrogen and nitrate ions “puzzle piece” method. “O” for the symbols, but you need 1b. acids ending in “-ous acid” came Ex You need TWO Br- ions to two nitrogens and three oxygens from “-ite” anions cancel out the one Ca+2, according to the Greek prefixes. Ex nitrous acid yields H+ and NO2-, because each bromide has only 3. Write the entire formula out hydrogen and nitrite ions a negative one charge. using the symbols and subscripts. 1c. acids starting with “hydro-“ and 3. Write the cation first in the Ex dinitrogen trioxide is N2O3 ending in “-ic acid” came from “-ide” formula and use subscripts to anions show how many of each ion Greek Prefixes [1-mono] [2-di] Ex hydronitric acid yields H+ and N-3 , you used in order to make [3-tri] [4-tetra] [5-penta] [6-hexa] hydrogen and nitride ions. charges add to zero. [7-hepta] [8-octa] [9-nona] [10- Ex calcium bromide has the deca] (memorize these) 2. Put acids together using their formula CaBr2 charges just like you do ionic BE CAREFULS: compounds. BE CAREFULS: 1. Writing the formula for Ex nitric acid must be HNO3 because 1. If you have more than of any molecules has NOTHING to do H+ and NO3- charges add up to zero. polyatomic ions, you must put with charges. Don’t let the ionic Ex sulfurous acid must be H2SO3 them in parentheses. compound system fool you. because you must add two H+ ions to Ex calcium nitrate is Ca(NO3)2 Ex You wouldn’t try to break cancel out one SO3-2 ion. but calcium bromide is CaBr2, carbon dioxide up into carbon and even though Br- and NO3- have oxide ions, but instead would use BE CAREFULS: the same charge. The nitrate is the MOLECULE system. 1. Don’t forget that most acids (all POLYATOMIC (more than one acids you have to name in 1st year atom) chemistry) begin with an H+ ion and an anion that contols the formula. 2. Be sure you don’t use the 2. Acids are similar to salts in the way roman numerals for the cations they’re named. with multiple possibilitiies. 3. Remember the tricks to naming Ex. iron (II) hydroxide is acids Fe(OH)2 not Fe(II)(OH)2 A.I ATE at the cafeteria and said IC B.The physician said I had 3. Don’t write the charges in appendicitis (appendic ITE – OUS) the final formula. C. I’d hide Rick (IDE HYDR O IC) Ex sodium iodide is NaI, not Na+I- when you’re done.