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Chapter 7 – Chemical Formulas and Chemical Compounds

Chapter 7 – Chemical Formulas and Chemical Compounds. 7-1 Chemical Names and Formulas. What’s so important about a chemical formula? It indicates the relative # of atoms of each kind in a chemical compound

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Chapter 7 – Chemical Formulas and Chemical Compounds

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  1. Chapter 7 – Chemical Formulas and Chemical Compounds

  2. 7-1 Chemical Names and Formulas • What’s so important about a chemical formula? • It indicates the relative # of atoms of each kind in a chemical compound • Molecular Compound: chemical formula reveals the # of atoms in a single molecule. C8H18 • Ionic Compound: consists of a lattice of positive and negative ions held together by mutual attraction.  Simplest ratio NaCl

  3. Al S O 2 3 12 Al2(SO4)3- How many atoms are there?

  4. Monoatomic Ions • Ions formed from a single atom • Ex. Na  Na1+ , O  O2- • Not all main-group elements form ions, C and Si form covalent bonds instead of ionic bonds • Sn and Pb are exceptions  lose only 2 e-s instead of 4 or sometimes they keep all 4 electrons.

  5. Naming Monoatomic Ions • Cations are identified by the elements name • Anions the ending of the element’s name is dropped. • The ending –ide is added. • Ex. Fluorine (F) = Fluoride ion (F-) • Nitrogen (N) = Nitride (N3-) • Flash Cards may be useful to memorize these!!!!

  6. Binary Ionic Compounds • Compounds composed of two different elements. • Ex. Magnesium and Bromine form Magnesium Bromide, MgBr2

  7. Rules for Ionic Compounds • 1. Write the symbols for the ions side by side. The cations go first. • Al 3+ O 2- • 2. Cross over the charges by using the absolute value of each ion’s charge as the subscript for the other ion. • Al2O3 • 3. Check subscript and divide them by their largest common factor to give the smallest possible whole-number ration. • 4. Write the formula

  8. Magnesium and iodine Potassium and sulfur Aluminum and chlorine Zinc and bromine Cesium and sulfur Strontium and oxygen Calcium and nitrogen MgI2 K2S AlCl3 ZnBr2 Cs2S SrO Ca3N2 Write the formula for the following:

  9. BaF2 CaO AgF CdO K3N NaI AlBr3 Barium Fluoride Calcium Oxide Silver Fluoride Cadmium Oxide Potassium Nitride Sodium Iodide Aluminum Bromide Name the following:

  10. The Stock System of Nomenclature • Some elements form two or more ions such as Fe, with different charges. • This system uses Roman numerals to indicate an ions’ charge • Fe 2+ or Fe 3+ • FeCl2 = iron (II) chloride • FeCl3 = iron (III) chloride

  11. Cu + and O 2- Fe 3+ and S 2- Cu 2+ and Cl - Sn 2+ and Cl - Hg 2+ and O 2- Sn4+ and S 2- V 2+ and F - V 4+ and Br - Write the formula and give the name for the following:

  12. Name the following: • CoI2 • HgI2 • PbS2 • CuBr2

  13. Compounds Containing Polyatomic ions • Oxyanions- polyatomic ions containing oxygen • Nitrate vs. Nitrite – (-ite less oxygen) • NO3- and NO2- • Sulfates, Nitrate, Chlorates

  14. Write the formulas for: • Copper(II) nitrate • Potassium iodide • Sodium hydroxide • Ammonium acetate • Calcium carbonate • Potassium permanganate • Sodium sulfate • Iron(III) nitrate

  15. Name the following: • Ag2S • NaMnO4 • Ba(OH)2 • NH4NO3 • Fe(ClO)2 • Ca(NO3)2 • K2SO3 • NaCH3COO

  16. # 1 2 3 4 5 6 7 8 9 10 # Mono Di Tri Tetra Penta Hexa Hepta Octa Nona deca Naming Binary Molecular Compounds

  17. Rules for Molecular Compounds • 1. The least electronegative element is first. It is given a prefix if it is more than one • 2. the second element is named by combining a prefix, the root of the word, and –ide ending • 3. the o or a at the end of the prfix is usually dropped when the word following begins with another vowel.

  18. Examples. • As2O5 = diarsenic pentoxide • PF5 = phosphorus pentafluoride • XeF4 = Xenon tetrafluoride • CCl4 = carbon tetrachloride • Carbon dioxide = CO2 • Dinitrogen pentoxide = N2O5 • Sulfur hexafluoride = SF6 • Dinitrogen monoxide = N2O

  19. Acids and Salts • Acids can be binary acids or oxyacids • Binary acids are acids that consist of H and a halogen, HCl hydrochloric acid • Oxyacids, contain H, P and a third element, Sulfuric Acid, H2S • Pg 214

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