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CHAPTER 9: Chemical Names and Formulas

CHAPTER 9: Chemical Names and Formulas. Objectives: To be able to name ionic and molecular compounds, and acids. 2. To be able to write the formulas of ionic and molecular compounds, and acids. Different Types of Formulas and Names. Ionic compounds Molecular compounds (molecules)

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CHAPTER 9: Chemical Names and Formulas

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  1. CHAPTER 9: Chemical Names and Formulas Objectives: To be able to name ionic and molecular compounds, and acids. 2. To be able to write the formulas of ionic and molecular compounds, and acids.

  2. Different Types of Formulas and Names • Ionic compounds • Molecular compounds (molecules) • Acids (a special type of molecule)

  3. Ionic Compounds Monatomic ions are ions of a single atom with a positive or negative charge resulting from the loss or gain of one or more valence electrons. Monatomic cations: Monatomic anions: Na+, Ca2+ Cl-, N3- Naming monatomic cations:Naming monatomic anions: Cations for groups 1, 2, & 3Anion start with the same metals have the same name asstem and end with -ide. the atoms, followed by ion or This is followed by ion or cation. anion. Na+ is sodium ion or sodium Cl- is chloride ion or cation. chloride anion.

  4. Other Names of Monatomic Ions Ion SymbolIon Name Li+ lithium ion (or cation) Ca2+ calcium ion (or cation) Al3+ aluminum ion (or cation) F- fluoride ion (or anion) O2- oxide ion (or anion) N3- nitride ion (or anion) P3- phosphide ion (or anion)

  5. Naming Binary Ionic Compounds Binary Ionic Compounds are composed of ions of two elements. To Name Binary Ionic Compounds, place the cation name first, followed by the anion name. FormulasNames NaCl sodium chloride CaF2 calcium fluoride Mg3N2 magnesium nitride AlP aluminum phosphide K2Se potassium selenide

  6. Polyatomic Ions • Polyatomic ions are ions composed of more than one type of atom (usually nonmentals) covalently bonded. • Examples of Polyatomic ions: NH4+ PO43- SO32- OH- • For naming polyatomic ions, you can use your common ion table to get the name. Compounds Names NH4Cl ammonium chloride Na3PO4 sodium phosphate Al2(CO3)3 aluminum carbonate Cu(NO2)2 copper(II) nitrite

  7. Naming Ions & Ionic Compounds of Transition Metals • Since some transition metals may have more then one charge, the charges of the cations must be determined and represented when naming transition metal ions and compounds with transition metal ions. • For example, iron is a transition metal and can have two common charges, Fe2+ and Fe3+. • When naming these ions, we use the Stock system which uses Roman numerals in parentheses after the metal name. • If the charge of the metal is not given directly, you must determine it by using the formula given. IonName of IonIonic CompoundName of Compound Fe2+ iron(II) ion FeCl2 iron(II) chloride Fe3+ iron(III) ion FeCl3 iron(III) chloride Cu+ copper(I) ion CuF copper(I) fluoride Pb4+ lead(IV) ion PbI4 lead(IV) iodide

  8. Steps to Writing Formulas of Ionic Compounds • Write the symbols of both ions including their charges remembering that the cation is placed first followed by the anion. sodium oxide Na+ O2- • Crisscross the value of the charges. This will make it so that the charges are balanced. Na+ O2- • Rewrite your new formula and make sure the charges cancel each other. Na2O two Na+ = +2 total charge one O2- = -2 is zero 4. If the charge is 1- or 1+, leave the number 1 out the formula since it is understood to be there. 5. If necessary, reduce the numbers of each atom by a common denominator since formula units represent the lowest ratio of ions in an ionic compound. 6. If there is more then one polyatomic ion present, use ( ) around the ion and then place the subscript outside of the ( ).

  9. Formula Practice: Binary Ionic Compounds Name of Compound IonsFormula aluminum iodide Al3+ I- AlI3 calcium phosphide Ca2+ P3- Ca3P2 barium sulfide Ba2+ S2- BaS rubidium bromide Rb+ Br- RbBr strontium nitride Sr2+ N3- Sr3N copper(II) chloride Cu2+ Cl- CuCl2 chromium(III) oxide Cr3+ O2- Cr2O3

  10. Naming Ionic Compounds with Transition Metals • It is necessary to determine the charge of a transition metals that can have more then one charge in order to name it. • This can be done by using the formula given and determining the charge of the anion first. • Remember that the total charges of the anion and cation must cancel each other out. FormulaIonsName CuCl Cu+ Cl- copper(I) chloride CuCl2 Cu2+ Cl- copper(II) chloride Fe2O Fe2+ O2- iron(II) oxide Fe2O3 Fe3+ O2- iron(III) oxide PbO2 Pb4+ O2- lead(IV) oxide PbCO3 Pb2+ CO32- lead(II) carbonate

  11. Formula Making: Compounds with Polyatomic Ions • Formula making with polyatomic ions is very similar to what you have learned so far. • Just DON’T forget to use ( ) around polyatomic ions when there is more then one of them! Names Ions Formula magnesium sulfate Mg2+ SO42- MgSO4 ammonium fluoride NH4+ F- NH4Cl lithium carbonate Li+ CO32- Li2CO3 calcium nitrate Ca2+ NO3- Ca(NO3)2 beryllium hydroxide Be2+ OH- Be(OH)2

  12. Naming Binary Molecular Compounds • When two nonmetals combine, they form a molecular compound whose formula shows the actual number of each kind of atom found in a molecule of the compound. • To name these compounds, we use a similar method to naming ionic cmps (see endings) except we can use prefixes to denote number of each atoms. • Note: when there is only atom of the first element in the compound • mono- is not used before the atom’s name. • Note: when using prefixes with atoms that start with a vowel, the last vowel of the prefix is dropped.

  13. Naming Practice: Binary Molecular Cmpds FormulaName NH3 nitrogen trihydride PCl5 phosphorous pentachloride SeF6 selenium hexafluoride NO nitrogen monoxide P2O7 diphophorous heptoxide C3H8 tricarbon octahydrogen

  14. Naming Acids • For now, the acids that we will learn how to name contain hydrogen ions, H+. (formulas start with H) Naming Rules: • When the anion name ends in -ide, the stem of the anion name begins with the prefix hydro- and ends with -ic. The name is then followed by the word acid. • When the anion name ends in -ite, the anion ends with -ous, followed by the word acid. • When the anion name ends in -ate, the anion name ends with -ic, followed by the word acid.

  15. Naming Acids Formula Anion Ending Acid Name HBr -ide hydrobromic acid HCl -ide hydrochloric acid HI -ide hydriodic acid H2S -ide hydrosulfuric acid H2SO4 -ate sulfuric acid H2SO3 -ite sulfurous acid H3PO3 -ite phosphorous acid H3PO4 -ate phosphoric acid HClO -ite hypochlorous acid HClO4 -ate perchloric acid

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