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Honors Chapter 9 (and some Chapter 7)

Honors Chapter 9 (and some Chapter 7). Chemical Names and Formulas. Chemical formula - combination of symbols that represent the composition of a compound Shows elements present and number of atoms. subscripts. Represent the number of atoms of that element in the compound

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Honors Chapter 9 (and some Chapter 7)

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  1. Honors Chapter 9 (and some Chapter 7) Chemical Names and Formulas

  2. Chemical formula - combination of symbols that represent the composition of a compound • Shows elements present and number of atoms

  3. subscripts • Represent the number of atoms of that element in the compound • No subscript is an “understood” 1

  4. NaCl • 1 Na 1 Cl • H2SO4 • 2 H 1 S 4 O • Ca(ClO3)2 ????? • 1 Ca 2 Cl 6 O

  5. Two types of compoundswe will learn how to write formulas for Ionic – transfer of electrons Called a “formula unit” Covalent – share electrons called “molecule”

  6. IONIC COMPOUNDS • Four different types we will learn about

  7. Metal + nonmetal (binary ionic) • Metal + polyatomic ion • Polyatomic ion + polyatomic ion • Polyatomic ion + nonmetal

  8. Ionic Charges • Monatomic ions – ions consisting of only one atom • Charges can often be determined by using the periodic table • Metallic elements – tend to lose electrons to form cations • Group 1 all 1+ • Group 2 all 2+

  9. Nonmetals • Nonmetals tend to gain electrons when they bond with metals – form anions

  10. Transition metals • Many have more than one common ionic charge Are going to use roman numerals

  11. Oxidation number • Indication of how many electrons it will gain or lose when it forms a bond • Gains or loses electrons – forms an ion • Charged particle • Can be found for each element on the periodic table • Refer to yours!!!

  12. Some elements have more than 1 oxidation number – that means they can form more than one type of compound

  13. When a single atom takes on a charge (by gaining or losing electrons) – it forms a “monatomic ion” • Ion made up of more than 1 atom – “polyatomic” ion

  14. Monatomic ions • Na+ Ca+2 Cl- O-2 • Polyatomic ions • CO3-2 ClO3- OH-

  15. Why would an atom want to form an ion? • Remember the “octet rule” • Wants a filled outer shell • For most atoms, that is 8

  16. Samples on board using electron dot notation • Na and Cl • Ca and Cl • Al and Cl • Ca and S • K and N you do

  17. 1) Metal + nonmetal • Metal always written first – has positive oxidation number (written first) • Nonmetal written second – has negative oxidation number

  18. Can use “criss-cross” method to arrive at correct formula. • Must remember to simplify subscripts if possible!! • Magnesium oxide - MgO

  19. Naming binary ionic compounds • Metal full name first • Nonmetal name with “ide” ending • NaCl sodium chloride • CaCl2 calcium chloride • LiF lithium fluoride • AlBr3 aluminum bromide

  20. Some metals have multiple oxidation numbers • Use Roman numerals to specify the oxidation number used • I, II, III, IV, V, VI, VII, VIII • Transition metals characteristically have multiple oxidation numbers • ONLY USE ROMAN NUMERALS IF THE METAL HAS MORE THAN ONE OXIDATION NUMBER LISTED

  21. Nonmetals may have more than one oxidation number, you just use the first number listed - NEGATIVE

  22. Examples: • Co, Ni, Cu, Fe, Mn • Always check before writing name for the compound • FeCl2 • Iron(II) chloride • FeO • Fe2O3

  23. Write formulas for the following • calcium sulfide • strontium bromide • chromium(III) chloride • iron(II) oxide

  24. CaS • SrBr2 • CrCl3 • FeO

  25. Name the following compounds • Fe2O3 • KI • CuO • NiCl3 • CrO3

  26. Iron(III) oxide • Potassium iodide • Copper(II) oxide • Nickel(III) chloride • Chromium(VI) oxide

  27. 2. Metal + polyatomic ion • Almost all polyatomic ions have a negative charge • 2 you are responsible for have a positive charge NH4+ and H3O+ • Polyatomic ions travel as a unit • Page 257 list of polyatomic ions

  28. NEVER CHANGE THE SUBSCRIPTS IN A POLYATOMIC ION • THAT MEANS NEVER!!!!!!!

  29. Can use same “criss-cross” method for determining the correct formula • Same rules apply – must factor the subscripts if you can (only the oxidation numbers that are used – NOT THE SUBSCRIPTS OF THE POLYATOMIC ION!!!!!!

  30. At first, always put a parenthesis around the polyatomic ion • Only time the parenthesis can be dropped is if a “1” criss-crosses down or if the subscript factors to a “1”

  31. Don’t forget to include a roman numeral in the name if the metal has multiple oxidation numbers!!!!!!

  32. Examples on board

  33. Naming • Metal name first (only use roman numeral if the metal has more than one oxidation number!!!) • Second is the name of the polyatomic ion – taken directly from the table!!

  34. Don’t make up your own name!!!!!!!!

  35. Characteristics of Ionic Compounds • Representative unit = “formula unit” • Type of elements: Metal with nonmetal • Physical state: crystalline solid (hard) • High melting point • Most are soluble in H2O

  36. Poor conductors of electricity in the solid state • But good conductors when melted (molten) or dissolved in H2O (aq) (ions free to move)

  37. Molecular Compounds (covalent) • Representative unit – “molecule” (bonded covalently) • Type of elements – nonmetals • Physical state – solid, liquid, gas • Solids – low melting point, brittle

  38. Molecule – electrically neutral group of atoms that act as a unit

  39. Naming binary molecular compounds • 2 elements in the compound • Both nonmetals! • 2 naming systems • Prefix system • Stock system (roman numerals) • Both systems are correct • I’m sure you will prefer the prefix system!

  40. Prefixes you must memorize! Number of Prefix used atoms 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca

  41. When 2 nonmetallic elements combine • Often do so in more than one way • Example CO CO2 • Problem with calling them both “carbon oxide”

  42. CO2 – you exhale. It is normally present in the air you breathe • CO – hopefully is not in the air you breathe • In large amount R.I.P. • Catalytic converter – cars • Converts CO to CO2

  43. Naming binary molecular compounds • Prefix + first element name • Followed by prefix + 2nd element name with “ide” ending • ******only time you can neglect a prefix is if the first element in the compound is a single atom

  44. PCl3 phosphorus trichloride • CO • Carbon monoxide (not monocarbon monoxide!)

  45. Don’t use “double vowels” • Change if a “tongue twister” • Monooxide  monoxide • Decaoxide  decoxide • Trioxide – is fine

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