2Counting AtomsThe subscript tells how many of that element is present.Eg: H2O2= 2 hydrogen, 2 oxygenIf there is no subscript next to the symbol, it counts as “1”.Eg: NaCl = 1 sodium & 1 chlorine
3Counting AtomsIf the subscripted number is outside of the parenthesis, it is distributed to all elements within the parenthesis.Eg: Ca(NO3)2 = NO3 x 2.A preceeding coefficient is multiplied to all atoms in the compound.Eg: 2NaCl = 2 sodium & 2 chlorine
4Counting Atoms Calcium Carbonate: CaCO3. Ca = Calcium = 1 C = Carbon = Oxygen =35Total atoms =
7IMPORTANT: ALL COMPOUNDS ARE NEUTRAL!!! Chemical FormulasThe simplest compounds contain 2 elements and are called Binary.In ionic binary compounds, a cation and an anion join together to form a neutral compound.Ionic compounds are made from a metal and a non-metal.IMPORTANT: ALL COMPOUNDS ARE NEUTRAL!!!Ionic CompoundCation+Anion=
8Chemical Formulas Potassium Bromide = KBr Calcium Bromide = CaBr2 Lithium Fluoride = LiFLithium Oxide = Li2ONote that the subscript has nothing to do with the name of the ionic compound.
9Chemical Names Example: LiF The element with the positive charge, cation (the metal) is written first.This element is given its usual name, in this case, Lithium.The second element is the anion. It’s name will be changed to end in “-ide”. Fluorine is changed to Fluoride.The compound’s name = Lithium Fluoride.
10Chemical Formula for Potassium Bromide Write the two symbols for the ions in the compounds, placing the symbol for the cation first.+1-1KBrKBrBalanced!Determine the charge of each ion from the oxidation state on the periodic table.If the charges are equal, drop them and write the formula.
11Calcium BromideIf the charges are not equal, “lasso” the number only (not the sign) to write the formula.1+ 22- 1CaBrCaBr2NOT Balanced!After seeing more examples, complete practice problems 1-10 on your worksheet.
12Transition Elements and Roman Numerals Some metals can form more than one type of ion and therefore, have more than one possible charge.To tell which charge is used, the chemical name contains a Roman numeral.The Roman numeral tells the charge of the cation.
13Transition Elements and Roman Numerals WARNINGRoman numerals are NEVER used in the chemical formula!!
14Rules to Write a Chemical Formula when Roman Numerals are Present To write the chemical formula for Iron (III) Sulfide:Write the two symbols for the ions in the compounds, placing the symbol for the cation first.Get the charge of the metal from the Roman numeral in ( ) after the metal and look up the anion’s charge.- 22Fe2S3+ 33FeS
15Rules to Write a Chemical Name when Roman Numerals are Needed If the metal has more than one oxidation state, the chemical name will contain a Roman numeral.Oxygen has a charge of -2 and there are 3 for a total charge of -6.Mn must have a charge of +6 to neutralize the -6 charge.Mn can have a charge of +7, 6, 4, 2 or 3Now write the chemical name using a roman numeral to represent the charge of the Manganese.Start with the anion to determine its overall negative charge.You CANNOT lasso up to determine the Roman numeral.Manganese (VI) OxideMnO3
16Let’s Try Again Fe2O3 Write the chemical name of Fe2O3. Rust The 2 Fe ions must have an overall charge of +6. So 6/2 = +3.Fe can have a charge of +2 or 3Oxygen has a charge of -2 and there are 3 for a total charge of -6.RustFe2O3Iron (III) OxideNow write the chemical name.Now do part C of your worksheet.
17Polyatomic Ions in Names The cation keeps its name.CaCO3CarbonateCalciumMade of more than one element so it is a polyatomic ion.The polyatomic ion also keeps its name, even though it is an anion.
18Polyatomic Ions in Formulas Barium Phosphate We recognize Phosphate as a polyatomic ion because it ends in “ate”.Get the charge of the polyatomic ion from the chart.Use the periodic table for the charge on your element.
19Barium Phosphate Ba PO4 Let’s Lasso! Add each ion’s charge. NO!! Write the chemical symbols.Are the charges balanced?- 33+ 22BaPO4We have 2 “PO4” ions so we need parentheses to separate the ion from the extra subscript.Ba3(PO4)2
20Let’s Try Again Mg OH Write the formula for Magnesium Hydroxide. + 2 2 - 11MgOHWe have 2 “OH” ions so we need parentheses to separate the ion from the subscript.Mg(OH)2Now do part D of your worksheet.
21Covalent CompoundsCovalent compounds are made from 2 non-metals and are binary.Since there are no ions involved, we don’t look at charges.The subscript to the right of the element tells the prefix to use for that element.SO2 = Sulfur Dioxide
23Some Covalent Compounds NF3nitrogen trifluorideN2Cl4dinitrogen tetrachlorideNO2nitrogen dioxideTOXIC!N2Odinitrogen monoxideLaughing GasNow do part E of your worksheet.
24Naming AcidsAcids = compounds that give off hydrogen ions when dissolved in water.Acids begin with H.Acids will always have some H next to an anion.The anion determines the name.
25Binary AcidsBinary Acids contain only 2 elements, the cation being hydrogen. Add the prefix hydro-, take the anion name and change the suffix -ide to –ic.HCl(aq) Hydrochloric AcidHF(aq) Hydrofluoric AcidHI(aq) Hydroiodic Acid
27OxyacidsTernary Acids contain 3 elements, hydrogen, oxygen and one other element (a polyatomic ion).The suffix is determined by the number of oxygens.If the anion ends in -ate, change the suffix to –ic acid.HNO3 =Hydrogen & Nitrate =Nitric Acid
29More OxyacidsIf the anion has one less oxygen & ends in -ite, change the suffix to –ous acid.Hydrogen & Nitrite =HNO2 =Nitrous AcidH2SO3 =Hydrogen & Sulfite =Sulfurous AcidHClO2 =Hydrogen & Chlorite =Chlorous Acid
31OxyacidsIf a third acid is formed with fewer oxygens than -ite, it is given the prefix hypo- and the suffix –ous.E.g. HClO = Hydrogen & hypochlorite = Hypochlorous AcidIf it has one more oxygen than -ate, it is given the prefix per- and the suffix –ic.E.g. HClO4 = hydrogen & perchlorate = Perchloric Acid.
32Writing Formulas for Acids Hydrogen will always be first.The name tells you the anion.Make sure the molecule is neutral.If the name starts with the prefix hydro- and ends with -ic, there is no oxygen in the formula.If there is no prefix, the suffix –ate comes from –ic and –ite comes from –ous.
33Write Formulas for these Acids hydroiodic acidacetic acidcarbonic acidphosphorous acidhydrobromic acidHIHC2H3O2H2CO3H3PO3HBr
34Naming Organic Compounds Hydrocarbons are compounds made of only carbon and hydrogen linked in long chains.Alkanes – have single bonded carbons so they are saturated.
35Naming Organic Compounds Alkenes – have double bonded carbons so they are unsaturated.Alkynes – have triple bonded carbonsWe’ll work with alkanes so hydrocarbons will have the suffix –ane.
38Organic CompoundsIf the atoms are linked in a ring rather than in a chain, the prefix cyclo- is added.Hexane in a chain CH3-CH2- CH2- CH2- CH2- CH3.Cyclohexane has 6 carbons in a ring.Each point represents a carbon.
39Organic Compounds If the chain is straight: CnH2n+2 n=#carbons E.g. C3H(2×3)+2 = C3H8 = PropaneCH3-CH2-CH3If the chain is cyclic: CnH2nE.g. C3H6 = cyclopropane