Chapter 8 – Nomenclature

Chapter 8 – Nomenclature 8.1 Names of Atoms Simple neutral atoms with no charge are named as is: Na is sodium atom, Ne is neon atom  Know the names and symbols for elements #1-20 and Ba, Co, I, Cu, Fe, Pb, Hg, Ag, Au, Zn, Sn, Sr, Ni, Br, Cr, Mn, Cd Ba Co I Zn Br Cd barium cobalt iodine zinc bromine cadmium Cu Fe Pb Sn Cr Sr copper iron lead tin chromium strontium Hg Ag Au Ni Mn mercury silver gold nickel manganese Definitions: • ionic compound: metal + nonmetal(s) (eg. NaCl, CaBr2, KMnO4, BaSO4) • covalent compound: 2 or more nonmetals (eg. NH3, CCl4) • monoatomic ion: charged ion from a single atom (eg Na+, Cl–, O2–) • polyatomic ion: charged ion containing 2 or more atoms (eg. OH–, SO42–) Charges o All elements alone have a charge of zero in their elemental state o Atoms get a charge and become ions when they have lost or gained electrons CATIONS - positively charged ion resulting from a neutral metal atom losing one or more e-‘s. Fixed Charge – The charge is always the same value – based on electron configuration. ➢ Typically group “A” representative metals. ▪ Group IA metals always have a +1 charge when they become an ion. Example: Na+ is sodium ion, K+ is potassium ion ▪ Group IIA metals always have a +2 charge when they become an ion. Example: Mg2+ is magnesium ion, Sr2+ is strontium Ion Charge +1 +2 +3 +4 +5 +6 Roman Numeral I II III IV V VI ion ▪ Group IIIA metals always have a +3 charge when they become an ion. Example: Al3+ is aluminum ion, Ga3+ is gallium ion ▪ Exceptions: The transition metals Ag+1, Zn2+, and Cd2+ have fixed charges. Variable Charge – The charge can be a different value. ➢ Typically group “B” transition metals. ▪ Use a Roman Numeral to indicate the charge of the cation if there is more than one possible charge. page 1 Example: Fe can have two charges Fe2+ is iron (II) ion Fe3+ is iron (III) ion ▪ Exceptions: Group A metals Sn and Pb Sn2+ is tin (II) ion, Sn4+ is tin (IV) ion Pb2+ is lead (II) ion, Pb4+ is lead (IV) ion ANIONS – negatively charged ion resulting from a neutral nonmetal atom gaining one or more e-‘s. ➢ Monatomic anions: Name changes for these anions by adding –ide ending. ➢ Always a fixed charged - based on electron configuration ▪ Group VA – gain 3 e-‘s to make 3- ions. N3nitride ion 3O atom: [He] ____ ____ ____   ____   P phosphide ion 2s 2p ▪ Group VIA – gain 2 e ‘s to make 2- ions O2oxide ion O2- ion: [He] ____ ____   ____  ____  2S sulfide ion 2s 2p ▪ Oxygen gains only two electrons. The resulting oxide ion is then isoelectronic to the noble gas neon, Ne. Group VIIA – gain 1 e- to make 1- ions Ffluoride ion Clchloride ion Br bromide ion Iiodide ion POLYATOMICS – two or more nonmetals covalently bonded with an overall charge. Here is the complete list of Polyatomic Ions you are responsible for this semester: Most Common Polyatomic Ions NH4+ = ammonium C2H3O2- = acetate OH- = hydroxide CN- = cyanide MnO4- = permanganate NO3- = nitrate NO2- = nitrite SO42- = sulfate SO32- = sulfite PO43- = phosphate CrO42- = chromate Cr2O72- = dichromate CO32- = carbonate HCO3- = hydrogen carbonate or bicarbonate *These are given to you on your CHM130 Periodic Table for quizzes and exams. 8.2 Ionic Formulas Compounds are Neutral They have no net charge so you must have enough cations and anions to equal zero. Na+ and Cl– make NaCl Na+ and CN– make NaCN Ba2+ and Cl– make BaCl2 since +1 and –1 = 0 since +1and –1 = 0 since +2 and 2(-1) = 0 page 2 Al3+ and O2– make Al2O3 Cu(II) and Br make CuBr2 since 2(+3) and 3(-2) = 0 since +2 and 2(-1) = 0 Polyatomic ions are just the same, remember to keep them together as a group  Express more than one polyatomic ion with subscripts and parentheses. Sr2+ and NO3- make Sr(NO3)2 Fe3+ and CO32– make Fe2(CO3)3 since +2 and 2(-1) = 0 since 2(+3) and 3(-2) = 0 8.3 Ionic Names ➢ The name is always the cation (usually metal) first then the anion + -ide ending. Fixed Charge Metal: metal name + nonmetal name + “ide” Variable Charge Metal: metal name (charge of metal) + nonmetal name + “ide” ➢ Don’t change the name for polyatomic ions to end in ide. ➢ For variable charge metals use a Roman Numeral to indicate the metal’s charge. How do you figure out the charge on a variable charge metal? Well you look at the anion’s charge. Cu(OH)2 Cu(OH)2 OH- Cu2+ OH- The subscript of 2 indicates there are 2 OH- ions in the formula. The overall compound has zero charge, so the Cu ion must be 2+ to cancel the two -1 charges from the two hydroxide ions present. ➢ Given the formula of a compound, predict the name: • • • • • • What is the name for NaCl? What is the name for K2SO4? What is the name for CuCl? What is the name for FePO4? Name for Ca(NO3)2? Name for Na2O? sodium chloride (no Roman # since know Na is +1) potassium sulfate (keep the polyatomic name as is) copper (I) chloride since Cl is –1 so Cu must be +1 iron (III) phosphate since PO4 is –3 so Fe must be +3 calcium nitrate sodium oxide Note: Never capitalize the names of compounds! ➢ Given the name of a compound, predict the formula:  You must know charges on ions formed by Group A main elements.  Know how to use polyatomic ions given on your Periodic Table! • • • • • • lithium sulfide calcium oxide iron (II) bromide potassium acetate gold (II) nitrite sodium iodide Li2S CaO FeBr2 KC2H3O2 Au(NO2)2 NaI since Li is +1 and S is –2 you need two Li’s since Ca is +2 and O is –2 you just need one of each since Fe is +2 and Br is –1 you need two Br’s since K is +1 and acetate is –1, need one of each since Au is +2 and NO2 is –1, need two nitrites since Na is +1 and I is –1, just need one of each page 3 8.4 Covalent Names Molecular Compounds: compounds consisting of 2 nonmetals. These are NOT ions, so no charges. You are not trying to add up to zero charge with these. Number of atoms of element indicated by Greek prefix before element name FIRST ELEMENT prefix (except mono) + nonmetal name # of atoms 1 Greek prefix mono # of atoms 6 Greek prefix hexa 2 di 7 hepta 3 tri 8 octa 4 tetra 9 nona 5 penta 10 deca SECOND ELEMENT prefix + 2nd nonmetal name + ide N2O4 2 nitrogen atoms = di 4 oxygen atoms = tetra dinitrogen tetraoxide or dinitrogen tetroxide Examples: • CO2 = carbon dioxide • PCl3 = phosphorus trichloride • N2S5 = dinitrogen pentasulfide • SF6 = sulfur hexafluoride • Cl2O7 = dichlorine heptaoxide Prefixes are ONLY used with molecular compounds. Roman numerals are ONLY used with variable charged metal ionic compounds. Polyatomic ions never change their name. ☺ CHAPTER 8 PRACTICE PROBLEMS Example 1: Circle all the examples below that are ionic compounds. HCl Example 2: K2O MgCl2 PF5 CuBr2 CaSO4 CH2O Circle all the examples below that are covalent compounds. HCl K2O MgCl2 PF5 CuBr2 CaSO4 CH2O page 4 Example 3: What ions are the following atoms most likely to make? calcium = _________ potassium = _________ sulfur = _________ aluminum = _________ nitrogen = _________ chlorine = _________ silver = _________ zinc = _________ Example 4: What is the name for: CuCl2, SrS, NiCrO4, Mg(NO3)2, Na3P, ZnCO3, KOH, Ca(CN)2 Example 5: What is the formula for sodium carbonate, copper(II) bromide, strontium fluoride, iron(III) nitride, silver sulfite, nickel(II) nitrate, cadmium phosphate, ammonium hydroxide, magnesium sulfate? Example 6: What is the name for CF4, CO, PO5, N2F4? What is the formula for diphosphorus tetraiodide, tribromine octaoxide, tetraphosphorus decasulfide, carbonic acid? Answers to Practice Problems Example 1: Circle all the examples below that are ionic compounds. metal-nonmetal HCl Example 2: K2O MgCl2 PF5 CuBr2 CaSO4 CH2O Circle all the examples below that are molecular compounds. nonmetals HCl K2O MgCl2 PF5 CuBr2 CaSO4 CH2O Example 3: calcium = sulfur = nitrogen = silver = Example 4: CuCl2 SrS NiCrO4 Mg(NO3)2 ZnCO3 Na3P KOH Ca(CN)2 Ca2+ S2N3Ag+ potassium = aluminum = chlorine = zinc = name copper(II) chloride strontium sulfide nickel(II) chromate magnesium nitrate zinc carbonate sodium phosphide potassium hydroxide calcium cyanide K+ Al3+ ClZn2+ Example 5: sodium carbonate copper(II) bromide strontium fluoride iron(III) nitride silver sulfite nickel(II) nitrate cadmium phosphate ammonium hydroxide magnesium sulfate formula Na2CO3 CuBr2 SrF2 FeN Ag2SO3 Ni(NO3)2 Cd3(PO4)2 NH4OH MgSO4 Example 6: carbon tetrafluoride, carbon monoxide, phosphorus pentaoxide, dinitrogen tetrafluoride, P2I4, Br3O8, P4S10, H2CO3 page 5