Nomenclature Chapter 4

Nomenclature = Naming Common names were created before there was a system in place More than 4 million chemical compounds, memorizing names would be impossible A system makes it much easier

Binary Compounds Compounds composed of 2 elements 2 types Metal and Nonmetal Two Nonmetals

4.1 Naming Compounds That Contain a Metal and a Nonmetal Remember: When metals and nonmetals combine the compound contains ions Resulting substance is a binary ionic compound Contain cation and anion in that order To name them simply name ions Cation is element name Anion is root of element name with –ide at end NaCl is sodium chloride

Certain metal ions form only one cation Na is always Na+ Cs is always Cs+ Ca is always Ca2+ We will call these Type I cations and they form Type I binary compounds Other metal ions can form more than one cation Cr can form Cr2+ or Cr3+ Lower oxidation number will end in –ous Higher oxidation number will end in -ic We will call these Type II cations and they form Type II binary compounds

Type I Binary Ionic Compounds Cation always named first, anion second When a single element is the cation we simply use its name When a single element is the anion take the root and add –ide Examples NaI is sodium iodide CaO is calcium oxide What would KI be? Potassium iodide What would CsBr be? Cesium bromide Do Practice problems on page 87

Type II Binary Ionic Compounds Need to specify which cation is used Is it Cr2+ or Cr3+? We will use Roman Numerals in name So if it is FeCl2 which Iron is it? Fe2+ (the ferrous ion) or Fe3+ (the ferric ion)? we know Chlorine has a 1- oxidation number so 2 (1-) = 2-, what must Fe be to cancel this out? Fe must be 2+ so it is Fe2+ So name would be Iron II chloride Table 4.2 page 90

4.2 Binary Compounds That Contain Only Nonmetals (Type III) Write first element Write second element Add prefix to 1st element (but not mono-) Add prefix to 2nd element Why do we do this? NO, N2O5, and NO2 would all be nitrogen oxide under the normal rules Instead they are Nitrogen monoxide, Dinitrogen pentoxide, and Nitrogen dioxide one –mono two - di three - tri four - tetra five - penta six - hexa seven - hepta eight - octa nine - nona ten - deca

4.3 Review Type I Type II Type III metal and nonmetal Metal cation has only 1 oxidation number Type II Metal and nonmetal Metal cation has more than 1 oxidation number Tell which ox. # it is with roman numerals Type III Nonmetal and nonmetal Use prefixes to name

Naming Binary Compounds

4.4 naming Compounds That Contain Polyatomic Ions FIRST: Copy Table 4.4 on page 100 into notes Polyatomic ion – a charged group of atoms bound together Oxyanion – oxygen and another element Smallest – hypo- Lower - -ite (If only 2, smallest) Higher - - ate (If only 2, largest) Largest – hyper

When naming compounds with polyatomic ions follow same rules but anion (second part of formula) is a polyatomic ion just name it

4.5 Naming Acids Acid – produces H+ ions (protons) in water Tastes sour (not a good test) It is like a molecule with a H+ attached to an anion If no oxygen Hydro- in front, -ic at end HCl is Hydrochloric acid If oxygen Root of central element of anion or anion name with –ic or –ous Anion ends in –ate then replace with –ic Anion ends with –ite then replace with -ous

4.6 Writing Formulas From Names You know how to do this