2Oxidation Numbers forthe Group A Elements1+2+3+3-2-1-NA
3When you write ions, use the element symbol and the oxidation number written as a superscript. brominesulfurcesiumcalled bromide in a compoundBr-1called sulfide in a compoundS-2Anions change end of name to –ide.Cs+1
4If you need the oxidation number for a transition or inner transition metal, it will be given to you because these elements typically have more than one oxidation number.Ox. # for transition/inner transition metals will be in the form of a Roman Numeral!Exceptions:Pb and Sn use Roman numerals even though they are NOT transition metalsAg and Zn do NOT use Roman Numerals even though they ARE transition metals
5example:nickel (II) chloride (NiCl2)The (II) belongs to nickelwhich means nickel has a +2 charge while chlorine has a -1 charge!
6What is the oxidation number for the metal in each compound? Pb+4Lead (IV) oxideScandium (II) nitrideSc+2
7Monatomic Ions A monatomic ion is an ion made up of one element. examples: H O F Ba+2Monatomic ions bond to make a binary compound.Binary compounds are made of a monatomic cation and a monatomic anion.
8To Write Formulas with Monatomic Ions, use the criss-cross method! bromine: name changed to bromide in a compoundWrite the formula for barium bromide.First: Write each element symbol and oxidation number.***Always write the positive ion first!!!Next: Criss-cross the oxidation numbers. Swap the ox. #’s and write them as SUBSCRIPTS (lose the + and – signs)Ba+2 Br-1Ba Br-1Ba1Br1=BaBr22
9Write the formulas for: Iron (III) chlorideSodium oxideMagnesium nitride
10Polyatomic IonsA polyatomic ion is an ion made up of more than one element.These are on the back of your periodic table!The entire polyatomic ion has an oxidation number (NOT the individual elements).
11Polyatomic IonsExample: PO4-3 is the polyatomic ion phosphate with an oxidation number of -3.Example: SO3-2 is the polyatomic ion sulfite with an oxidation number of -2.Most polyatomic ions end in the suffix –ate or –ite.
12To write formulas with polyatomic ions: First: Write each element and polyatomic ion symbol and oxidation number.***Always write the positive ion first!!!Next: Place polyatomic ion in PARANTHESESFinally: criss cross the oxidation numbersNEVER, NEVER, NEVER, EVER CHANGE THE SUBSCRIPT WITHIN THE POLYATOMIC ION ITSELF!
16Nomenclature of Ionic Compounds Nomenclature means naming.Naming Ionic Compounds with Monatomic IonsFirst: Name the cation (positive ion) – DO NOT CHANGE THE CATION’S NAME IN ANY WAY and write it down.Note: If the cation is a transition or inner transition metal, you must indicate its charge (the oxidation number) using Roman numerals in parentheses after the metal’s name.Ex: iron (II) chloride; its chemical formula is:FeCl2
17Oxygen ______________ Sulfur ______________ Nitrogen ______________ Ex: What would these anions be named in a compound?Oxygen ______________Sulfur ______________Nitrogen ______________Iodine ______________Phosphorus ______________Chlorine ______________
19Naming Ionic Compounds with Polyatomic Ions First: Name the cation ion first (NEVER CHANGE THE CATION’S NAME).Note: If the cation is a transition or inner transition metal, you must indicate its charge using Roman Numerals in parentheses after the metal’s name. Ex: iron (II) hydroxide (its chemical formula is Fe(OH)2)Next: Name the polyatomic ion – ON THE BACK OF THE PT – (NEVER CHANGE THE POLYATOMIC’S NAME).HINT: Polyatomic ions usually end in –ate or –ite!