Chapter 9 Chemical Names and Formulas

Recalling the Periodic Table Metals(Left) Nonmetals (Right) Metalloids (on line) Physical State Reflect light? Malleability/Ductility: hammered/draw to wire? Melting point Conduct heat/electricity?

Recalling the Periodic Table (use chapter 5/6 if needed) Metals(Left) Nonmetals (Right) Metalloids (on line) Physical State Solid (except Hg) Solid or Gas (Br-liquid)Solid Reflect light? Yes (if polished) NoNo Malleability/Ductility: hammered/draw to wire? YesNoYes Melting point High (many > 800°C) LowVarious Conduct heat/electricity? YesNo Not well

Understanding the Periodic Table Groups- vertical columns within the periodic table Groups- vertical columns within the periodic table Representative elements- group “A” elements Representative elements- group “A” elements Transition metals- group “B” elements Transition metals- group “B” elements Important families of elements: Alkali Metals- metals in group 1A that form +1 ions Alkaline Earth Metals- metals in group 2A that form +2 ions Halogens- nonmetals in group 7A that for -1 ions Noble gases- Nonmetals located in far right column that are generally nonreactive

Interpreting Chemical Formulas Atoms vs. Ions Atoms vs. Ions Atom- NEUTRAL species with equal number of protons and electrons Atom- NEUTRAL species with equal number of protons and electrons Ion- CHARGED species with unequal number of protons and electrons Ion- CHARGED species with unequal number of protons and electrons Cation- (+) ion [lost electron(s)] Cation- (+) ion [lost electron(s)] Anion- (-) ion [gained electron(s)] Anion- (-) ion [gained electron(s)]

Interpreting Chemical Formulas Compound- collection of atoms that is NEUTRAL overall Compound- collection of atoms that is NEUTRAL overall Molecular compound- composed of nonmetals Molecular compound- composed of nonmetals Ionic compound- composed of cations and anions (metal ions and nonmetal ions) in a crystal lattice Ionic compound- composed of cations and anions (metal ions and nonmetal ions) in a crystal lattice

Interpreting Chemical Formulas Interpreting Formulas Interpreting Formulas Molecular formula- indicates type and amount of each atom in a compound Molecular formula- indicates type and amount of each atom in a compound Diatomic elements- Br I N Cl H O F exist as two atom molecules when ALONE! Diatomic elements- Br I N Cl H O F exist as two atom molecules when ALONE! Formula unit- lowest ratio of ions in an ionic compound (so that charge is zero) Formula unit- lowest ratio of ions in an ionic compound (so that charge is zero) Ratio of Atoms in a Compound Ratio of Atoms in a Compound Law of Definite Proportions Law of Definite Proportions Law of Multiple Proportions Law of Multiple Proportions

Writing Formulas of Ionic Compounds Writing Formulas of Ionic Compounds (Ex: sodium oxide) Writing Formulas of Ionic Compounds (Ex: sodium oxide) Identify charge on metal and nonmetal ions- Group # generally reveals charge (Na +1, O 2- ) Identify charge on metal and nonmetal ions- Group # generally reveals charge (Na +1, O 2- ) Criss-cross superscripts to balance charges Criss-cross superscripts to balance charges (Na 2 O) Check if total formula has 0 charge (2 Na +1) + (1 O -2) = 0 Check if total formula has 0 charge (2 Na +1) + (1 O -2) = 0 Write answer with subscripts (Na 2 O) Write answer with subscripts (Na 2 O) Note: Polyatomic (many atom) ions are written same except parenthesis are put around them if subscripts are added Note: Polyatomic (many atom) ions are written same except parenthesis are put around them if subscripts are added

Naming Ionic Compounds Nontransition metal cations named as elements Nontransition metal cations named as elements Nonmetal anions end in –ide Nonmetal anions end in –ide Polyatomic ions usually end in –ate or –ite Polyatomic ions usually end in –ate or –ite Exceptions: OH -1, CN -1, and NH 4 +1 Exceptions: OH -1, CN -1, and NH 4 +1 KNOW: Table 9.3 p. 257 KNOW: Table 9.3 p. 257 If anion is polyatomic, name normally If anion is polyatomic, name normally (CaSO 4 = calcium sulfate) If anion is monatomic, add –ide at end (CaCl 2 = calcium chloride) If anion is monatomic, add –ide at end (CaCl 2 = calcium chloride)

Stock System- predicting transition metal ion charge Some metals can exist in several forms (Ex: Cu +1, Cu +2 Some metals can exist in several forms (Ex: Cu +1, Cu +2 KNOW: Cu, Fe, Sn, Pb (2 names and common charges) ***p. 255*** KNOW: Cu, Fe, Sn, Pb (2 names and common charges) ***p. 255*** Lower charge => suffix –ous Lower charge => suffix –ous Higher charge => suffix -ic Higher charge => suffix -ic Chemical formula used to decide which ion is present (Ex: CuCl 2 – must be Cu +2 ) Chemical formula used to decide which ion is present (Ex: CuCl 2 – must be Cu +2 ) Name puts ion charge in parenthesis (Ex: copper (II) chloride) ***only done for metals after group 2A*** Name puts ion charge in parenthesis (Ex: copper (II) chloride) ***only done for metals after group 2A***

Writing Formulas of Molecular Compounds Writing Formulas (Example: Carbon Dioxide) Writing Formulas (Example: Carbon Dioxide) More metallic element first (Ex: carbon before oxygen) More metallic element first (Ex: carbon before oxygen) Write symbols for each element next to one another (Ex: CO) Write symbols for each element next to one another (Ex: CO) Add subscripts to relate number of each atom in the molecule (Ex: CO 2 ) Add subscripts to relate number of each atom in the molecule (Ex: CO 2 ) Greek Prefixes- KNOW: Table 9.4 p. 269 Greek Prefixes- KNOW: Table 9.4 p. 269

Naming Molecular Compounds Naming Binary Molecular Compounds (Ex: SO 3 ) Naming Binary Molecular Compounds (Ex: SO 3 ) Name in order appearing in formula Name in order appearing in formula (Ex: sulfur oxygen) Replace ending of last element with -ide (Ex: sulfur oxide) Replace ending of last element with -ide (Ex: sulfur oxide) Add prefixes to indicate number of each atom in molecule (Ex: sulfur trioxide) Note: mono is usually dropped Add prefixes to indicate number of each atom in molecule (Ex: sulfur trioxide) Note: mono is usually dropped

Acids Acids- form hydronium ion in water Acids- form hydronium ion in water Formula starts with H atom Formula starts with H atom H atom given off in water to make H 3 O +1 ion H atom given off in water to make H 3 O +1 ion KNOW: names and formulas on p. 272 KNOW: names and formulas on p. 272