Chemistry 20 – Unit 3
          Elements, Compounds and Nomenclature
    the term “nomenclature” refers to “naming”
•

   ...
Nonmetals
    when naming nonmetals, we simply state the
•

    elemental name given on the periodic table
    when writin...
Naming Compounds
    a compound is a pure substance made by combining
•

    at least two different elements in a specific...
Naming Ionic Compounds
    the first element gets its normal elemental name
•

    as found on the periodic table
    the ...
oxygen and aluminum
         •


              Al 3+ and O 2–
                   Al 3+ O 2–
                   Al –2 O +3
...
Creating the Formula and Naming Ionic
   Compounds Using Complex Ions
    when a simple positive ion is combined with a
•
...
Naming Ionic Compounds Using Multiple Ion
Charges
    some metallic ions have more than one charge
•

    for example, iro...
Hydrated Compounds
    some compounds have a strange-looking formula
•

    which has water added at the end, such as
    ...
Naming Molecular Compounds
    molecular compounds are formed by combining
•

    nonmetallic elements
    when these elem...
there is no general rule for determining states of
•

    matter
    each molecular compound has its own
•

    characteri...
Hydrogen Compounds
         hydrogen compounds are those which contain a
    •

         hydrogen at the beginning of the ...
Properties of Acids
         1. turns litmus indicator red
         • tastes sour

         • neutralizes bases

         ...
Example: Give the chemical formula for
         hydrosilicic acid.
    the acid name came from hydrogen silicate,
•

    t...
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  1. 1. Chemistry 20 – Unit 3 Elements, Compounds and Nomenclature the term “nomenclature” refers to “naming” • chemical nomenclature is the organized system • chemists use to name substances and write their chemical formulas when writing any formula for any substance we • first assume that the substance exists on its own, at room temperature if special conditions exist, states of matter are • adjusted Naming Pure Elements Metals when naming metals, we simply state the • elemental name given on the periodic table when writing the formula for any pure metal we • simply write the elemental symbol (no subscripts) inclusion of states of matter is very important, so • we must always indicate a solid state, the exception being mercury, Hg(l) Chemistry 20 – Unit 3 Page 1 Overhead Notes Elements, Compounds and Nomenclature
  2. 2. Nonmetals when naming nonmetals, we simply state the • elemental name given on the periodic table when writing the formula for any pure nonmetal • we write the elemental symbol with subscripts for some of the nonmetals, because we must also be aware of how it exists at room temperature for most nonmetals, you’ve just got to memorize • their formulas and their natural states of matter all nobles gases are monatomic: He(g) , Ne(g) , Ar(g) , • Kr(g) , Xe(g) , Rn(g) diatomic elements include: • • nitrogen – N2(g) • oxygen – O2(g) • all halogens: fluorine – F2(g) chlorine – Cl2(g) bromine – Br2(l) iodine – I2(s) astatine – At2(s) polyatomic elements include: • • phosphorous – P4(s) • sulfur – S8(s) all other nonmetals are monatomic and solid, • except bromine Chemistry 20 – Unit 3 Page 2 Overhead Notes Elements, Compounds and Nomenclature
  3. 3. Naming Compounds a compound is a pure substance made by combining • at least two different elements in a specific ratio Ionic Compounds an ionic compound is formed by taking one • metallic ion and combining it with one nonmetallic ion or a complex ion Binary Ionic Compounds only one metallic ion and one nonmetallic ion are • combined Process for Creating the Formula: find the elements - list their ions - place positive ions (cations) first, followed by - negative ions (anions) criss-cross their charges to create the correct - ratio of each element and simplify charges (reduce) the state of matter for all ionic compounds is - solid Chemistry 20 – Unit 3 Page 3 Overhead Notes Elements, Compounds and Nomenclature
  4. 4. Naming Ionic Compounds the first element gets its normal elemental name • as found on the periodic table the second element’s name has an “ide” ending • (regardless of the ratios found in the formula) Examples: sodium and chlorine • Na+ and Cl – Na + Cl – Na –1 Cl +1 NaCl (one’s are ignored) NaCl(s) sodium chloride magesium and iodine • Mg 2+ and I – Mg 2+ I – Mg –1 I 2+ MgI2 MgI2(s) magnesium iodide Chemistry 20 – Unit 3 Page 4 Overhead Notes Elements, Compounds and Nomenclature
  5. 5. oxygen and aluminum • Al 3+ and O 2– Al 3+ O 2– Al –2 O +3 Al2O3 Al2O3(s) aluminum oxide oxygen and calcium • Ca 2+ and O 2– Ca 2+ O 2– Ca –2 O +2 Ca2O2 *note: subscripts are simplified for ionic compounds CaO CaO(s) calcium oxide Chemistry 20 – Unit 3 Page 5 Overhead Notes Elements, Compounds and Nomenclature
  6. 6. Creating the Formula and Naming Ionic Compounds Using Complex Ions when a simple positive ion is combined with a • complex ion the process is as follows: • list both positive and negative ions • combine both • use brackets for the complex ion • criss-cross their charges • simplify subscripts when naming the compound, use the normal first • name for the metallic ion and copy the given name of the complex ion, which is found in the complex ion table Examples: calcium and hydroxide • Ca 2+ and OH – Ca 2+ and (OH) – Ca –1 (OH) 2+ Ca1(OH)2 since 1’s are not required • Ca(OH)2(s) note that if a 1 should appear after the • brackets, the brackets are not required Chemistry 20 – Unit 3 Page 6 Overhead Notes Elements, Compounds and Nomenclature
  7. 7. Naming Ionic Compounds Using Multiple Ion Charges some metallic ions have more than one charge • for example, iron has Fe2+ and Fe3+ • in these cases it is necessary to actually state which • ion is being used Roman numerals are used after each multiple- • charged ion Example iron and oxygen Fe2+ and O2– FeO(s) named iron (II) oxide or Fe3+ and O2– Fe2O3(s) named iron (III) oxide some tables may use old, “classical” names that • end with “ic” or “ous” “ic” ending is for the ion that has the greater • charge Example Fe3+ is also called ferric Fe2+ is also called ferrous FeO(s) is also called ferrous oxide Fe2O3(s) is also called ferric oxide Chemistry 20 – Unit 3 Page 7 Overhead Notes Elements, Compounds and Nomenclature
  8. 8. Hydrated Compounds some compounds have a strange-looking formula • which has water added at the end, such as CuSO4⋅ 5 H2O(s) these are still ionic compounds and exist as solids • at room temperature the only thing we have to do is to state how many • waters are involved so, for CuSO4 ⋅ 5 H2O(s) , the first part is named as • copper (II) sulfate and then we add that there are 5 waters the Latin prefix for 5 is penta and water is called • hydrate the name becomes copper (II) sulfate pentahydrate • Number Latin Prefix Number Latin Prefix 1 Mono 6 hexa 2 Di 7 hepta 3 Tri 8 octa 4 Tetra 9 nona 5 Penta 10 deca Chemistry 20 – Unit 3 Page 8 Overhead Notes Elements, Compounds and Nomenclature
  9. 9. Naming Molecular Compounds molecular compounds are formed by combining • nonmetallic elements when these elements are combined they may form • more than one compound carbon and oxygen may combine to form CO(g) or • CO2(g) nitrogen and oxygen may combine to form NO(g) or • NO2(g) or N2O4(g) note that subscripts are not simplified and another • naming system is used Example CO2(g) is made from carbon and oxygen • the first element gets the normal name • the second element gets and “ide” ending • now we must state how many of each element • is being used by inserting prefixes before each element name there is one carbon (monocarbon) and two • oxygens (dioxide) if the first element is a “mono” the prefix is • ignored but is used for the second element NO(g) is nitrogen monoxide • NO2(g) is nitrogen dioxide • N2O4(g) is dinitrogen tetroxide • Chemistry 20 – Unit 3 Page 9 Overhead Notes Elements, Compounds and Nomenclature
  10. 10. there is no general rule for determining states of • matter each molecular compound has its own • characteristic state of matter at room temperature and these are learned as you go along some molecular compounds have classical names • that have no logic involved in their naming system these we just memorize • Examples H2O(l) is water NH3(g) is ammonia O3(g) is ozone CH4(g) is methane C6H12O6(s) is glucose C12H22O11(s) is sucrose CH3OH(g) is methanol C2H5OH(l) is ethanol H2O2(l) is hydrogen peroxide H2S(g) is hydrogen sulfide Chemistry 20 – Unit 3 Page 10 Overhead Notes Elements, Compounds and Nomenclature
  11. 11. Hydrogen Compounds hydrogen compounds are those which contain a • hydrogen at the beginning of the chemical formula and are dissolved in water (aqueous) • Examples: HCl (g) , HNO 3(aq) hydrogen bonds covalently (shares electrons) to • nonmetals to form a molecular compound which may be any state of matter, depending on the species being formed most hydrogen compounds are named as acids • the only exceptions to this rule are the following • pure substances • HCl (g) – hydrogen chloride • H2S(g) – hydrogen sulfide • HCN (g) – hydrogen cyanide when hydrogen compounds dissolve in water • they form acidic solutions • HCl (g) is bubbled into water to form a solution called hydrochloric acid Chemistry 20 – Unit 3 Page 11 Overhead Notes Elements, Compounds and Nomenclature
  12. 12. Properties of Acids 1. turns litmus indicator red • tastes sour • neutralizes bases • conducts an electrical current • pH is lower than 7 Naming Acids Naming acids is easy if we follow this table: hydrogen ___ide becomes hydro___ic acid hydrogen ___ate becomes ________ic acid hydrogen ___ite becomes ________ous acid Examples: Name the following acids. HF(aq) – the normal name given to this chemical is • hydrogen fluoride, therefore, hydrogen fluoride becomes hydrofluoric acid HNO3(aq) – the normal name given to this chemical • is hydrogen nitrate, therefore, hydrogen nitrate becomes nitric acid HNO2(aq) – the normal name given to this chemical • is hydrogen nitrite, therefore, hydrogen nitrite becomes nitrous acid We can read the table backwards to write out the chemical formula of a given acid name. Chemistry 20 – Unit 3 Page 12 Overhead Notes Elements, Compounds and Nomenclature
  13. 13. Example: Give the chemical formula for hydrosilicic acid. the acid name came from hydrogen silicate, • therefore the formula must be H2SiO3(s) now change states to give the acid formula, • H2SiO3(aq) Classification of Acids Binary Acids: contain a hydrogen and one other kind of atom Example: HCl(aq) Oxo Acids: contain a hydrogen, an oxygen and one other kind of atom Example: HNO3(aq) Chemistry 20 – Unit 3 Page 13 Overhead Notes Elements, Compounds and Nomenclature

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