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Chapter 6: Nomenclature Formulas Describe Compounds H2OH2O Water: 2 Hydrogen atoms and 1 Oxygen atom C 12 H 22 O 11 Sucrose (table sugar): 12 atoms of.

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Presentation on theme: "Chapter 6: Nomenclature Formulas Describe Compounds H2OH2O Water: 2 Hydrogen atoms and 1 Oxygen atom C 12 H 22 O 11 Sucrose (table sugar): 12 atoms of."— Presentation transcript:

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2 Chapter 6: Nomenclature Formulas Describe Compounds H2OH2O Water: 2 Hydrogen atoms and 1 Oxygen atom C 12 H 22 O 11 Sucrose (table sugar): 12 atoms of Carbon, 22 atoms of Hydrogen and 11 atoms Oxygen

3 Chapter 6: Nomenclature 4 Mg(NO 3 ) 2 A number in front of a molecule means that you have more than one molecule; it is often referred to as coefficient A subscript number after an element means that you have more than 1 atom for that element A subscript number after a parenthesis means that all the atoms in the parenthesis are present in that molecule multiple times. If the molecule is an ion a superscript number represents the charge of the molecule

4 Order of Elements in a Formula metals written first – NaCl nonmetals written in order from Table 5.1 – CO 2 – occasional exceptions for historical or informational reasons H 2 O, but NaOH Table 5.1 Order of Listing Nonmetals in Chemical Formulas CPNHSIBrClOF

5 Classifying Materials atomic elements = elements whose particles are single atoms molecular elements = elements whose particles are multi-atom molecules molecular compounds = compounds whose particles are molecules made of only nonmetals ionic compounds = compounds whose particles are cations and anions

6 Molecular Elements Certain elements occur as 2 atom molecules Rule of 7’s – there are 7 common diatomic elements – find the element with atomic number 7, N – make a figure 7 by going over to Group 7A, then down – don’t forget to include H 2 H2H2 Cl 2 Br 2 I2I2 7 VIIA N 2 O 2 F 2

7 Molecular Compounds two or more nonmetals smallest unit is a molecule

8 Ionic Compounds metals + nonmetals no individual molecule units, instead have a 3-dimensional array of cations and anions made of formula units

9 Molecular View of Elements and Compounds

10 Step1 - Common Names - Exceptions H 2 O = water, steam, ice NH 3 = ammonia CH 4 = methane NaCl = table salt C 12 H 22 O 11 = table sugar

11 Step 2 - Classifying Compounds Compounds containing a metal and a nonmetal = binary ionic – Type I and II Compounds containing a polyatomic ion = ionic with polyatomic ion Compounds containing two nonmetals = binary molecular compounds Compounds containing H and a nonmetal = binary acids Compounds containing H and a polyatomic ion = oxyacids

12 Step 3 - Formula-to-Name Rules for Ionic Made of cation and anion Name by simply naming the ions – If cation is: Type I metal = metal name Type II metal = metal name(charge) Polyatomic ion = name of polyatomic ion – If anion is: Nonmetal = stem of nonmetal name + ide Polyatomic ion = name of polyatomic ion

13 Monatomic Nonmetal Anion determine the charge from position on the Periodic Table to name anion, change ending on the element name to –ide 4A = -45A = -36A = -27A = -1 C = carbideN = nitrideO = oxideF = fluoride Si = silicideP = phosphideS = sulfideCl = chloride

14 Metal Cations Type I – metals whose ions can only have one possible charge IA, IIA, (Al, Ga, In) – determine charge by position on the Periodic Table IA = +1, IIA = +2, (Al, Ga, In = +3) Type II – metals whose ions can have more than one possible charge – determine charge by charge on anion How do you know a metal cation is Type II? its not Type I !!!

15 Type I Binary Ionic Compounds Contain Metal Cation + Nonmetal Anion Metal listed first in formula & name 1.name metal cation first, name nonmetal anion second 2.cation name is the metal name 3.nonmetal anion named by changing the ending on the nonmetal name to -ide

16 Type II Binary Ionic Compounds Contain Metal Cation + Nonmetal Anion Metal listed first in formula & name 1.name metal cation first, name nonmetal anion second 2.metal cation name is the metal name followed by a Roman Numeral in parentheses to indicate its charge – determine charge from anion charge – Common Type II cations in Table nonmetal anion named by changing the ending on the nonmetal name to -ide

17 Some Common Polyatomic Ions NameFormula acetateC2H3O2–C2H3O2– carbonateCO 3 2– hydrogen carbonate (aka bicarbonate) HCO 3 – hydroxideOH – nitrateNO 3 – nitriteNO 2 – chromateCrO 4 2– dichromateCr 2 O 7 2– ammoniumNH 4 + NameFormula hypochloriteClO – chloriteClO 2 – chlorateClO 3 – perchlorateClO 4 – sulfateSO 4 2– sulfiteSO 3 2– hydrogensulfate (aka bisulfate) HSO 4 – hydrogensulfite (aka bisulfite) HSO 3 –

18 Step 3- Formula-to-Name Rules for Molecular we will not learn the rules for molecular compounds with more than 2 elements for binary molecular: – name first nonmetal – then name second nonmetal with ide ending – then give each name a prefix to indicate its subscript in the formula

19 Binary Molecular Compounds of 2 Nonmetals 1.Name first element in formula first – use the full name of the element 2.Name the second element in the formula with an - ide – as if it were an anion, however, remember these compounds do not contain ions! 3.Use a prefix in front of each name to indicate the number of atoms a)Never use the prefix mono- on the first element

20 Subscript - Prefixes 1 = mono-; – not used on first nonmetal 2 = di- 3 = tri- 4 = tetra- 5 = penta- 6 = hexa- 7 = hepta- 8 = octa- drop last “a” if name begins with vowel

21 Acids Contain H +1 cation and anion – in aqueous solution Binary acids have H +1 cation and nonmetal anion Oxyacids have H +1 cation and polyatomic anion

22 Formula-to-Name Acids acids are molecular compounds that often behave like they are made of ions All names have acid at end Binary Acids = hydro prefix + stem of the name of the nonmetal + ic suffix Oxyacids – if polyatomic ion ends in –ate = name of polyatomic ion with –ic suffix – if polyatomic ion ends in –ite = name of polyatomic ion with –ous suffix

23 Formula-to-Name Flow Chart

24 Writing the Formulas from the Names For binary molecular compounds, use the prefixes to determine the subscripts For Type I, Type II, Ternary Compounds and Acids 1.Determine the ions present 2.Determine the charges on the cation and anion 3.Balance the charges to get the subscripts

25 Compounds that Contain Ions compounds of metals with nonmetals are made of ions – metal atoms form cations, nonmetal atoms for anions compound must have no total charge, therefore we must balance the numbers of cations and anions in a compound to get 0 charge if Na + is combined with S 2-, you will need 2 Na + ions for every S 2- ion to balance the charges, therefore the formula must be Na 2 S

26 Writing Formulas for Ionic Compounds 1.Write the symbol for the metal cation and its charge 2.Write the symbol for the nonmetal anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the sum of the charges of the cation cancels the sum of the anions

27 Write the formula of a compound made from aluminum ions and oxide ions 1.Write the symbol for the metal cation and its charge 2.Write the symbol for the nonmetal anion and its charge 3.Charge (without sign) becomes subscript for other ion 4.Reduce subscripts to smallest whole number ratio 5.Check that the total charge of the cations cancels the total charge of the anions Al +3 column IIIA O 2- column VIA Al +3 O 2- Al 2 O 3 Al = (2)∙(+3) = +6 O = (3)∙(-2) = -6

28 Formula Mass the mass of an individual molecule or formula unit also known as molecular mass or molecular weight sum of the masses of the atoms in a single molecule or formula unit – whole = sum of the parts! mass of 1 molecule of H 2 O = 2(1.01 amu H) amu O = amu


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