Chemical Nomenclature: Formula Writing & Naming Compounds

1. Chemical Nomenclature:Formula Writing & Naming Compounds

2. Chemical Formula • The representation of a substance using symbols (letters) and subscripts (numbers) H2O The subscripts tell you how many atoms a compound is composed of. Water is made of 2 atoms of Hydrogen and 1 atom of oxygen

3. Writing Formulas for BinaryMolecules aka Binary Covalent Compounds. • Binary • made of 2 different elements • Molecules are Covalently bonded together • Both elements are non-metals • To the right of the “staircase” AND Hydrogen

4. Ex. Phosphorus pentoxide PO5 • Write the symbols for the elements in order • ide refers to an element except peroxide & hydroxide • Subscripts are written from prefixes and follow the symbol • Mono = one Di = two Tri = three • Tetra = four Penta = 5 Hexa = 6

5. Mono never STARTS a name! Practice • Carbon dioxide • CO2 • Dihydrogen monoxide • H2O • Sulfur hexafluoride • SF6 • Phosphorous pentachloride • PCl5

6. Formula Writing for Ionic Compounds • All ionic formulas are made of 2 parts A / B • A is positive B is negative A can be: Metal or Polyatomic ion B can be: Non-Metal or Polyatomic ion

7. Ionic Names with Roman Numerals Copper II Chloride Copper II Chlorate • Write the symbols ( -ate is a polyatomic ion) • The positive oxidation state for the metal is given to you as a Roman Numeral You know the charge on the anion. It’s based on the number of valence e-

8. Make your charges cancel out • Write formula & reduce if you can • “1” doesn’t need to be written CuCl2 Cu(ClO3)2

9. Practice • Lead II oxide • PbO • Lead IV oxide • PbO2

10. Ionic Names without Roman Numerals Potassium NitridePotassium Nitrate • Write down the symbols • If polyatomic ion look it up and write it in parenthesis. Don’t change it! • Assign oxidation states / charges Part A will be positive: you should know it! Part B will be negative and you should know them  or it’s a PAI (look it up)

11. “Crisscross” 4. Write formula - REDUCE! • “1” doesn’t need to be written K3N KNO3

12. Practice • Calcium Phosphate Ca3(PO4)2 • Magnesium Hydroxide Mg(OH)2

13. Formula Writing for 2 polyatomic ions Ammonium Phosphate • Write separate formulas in parenthesis • NEVERchange what’s inside!!!!!!!!!! • Assign charges • Make the charges cancel out with subscripts & write your final answer…….. (NH4)3PO4

14. Practice • Ammonium Nitrate NH4NO3 • Ammonium Hydroxide NH4OH

15. Naming……..

16. Count the number of atoms as a prefix mono = one di = two tri = three tetra = four . . . 2. Write the prefix before the names of the elements Mono never STARTS a name Naming Binary Molecules. . . both elements are non-metals

17. Write the name of the second element • end the name with -ide • hydrogen hydride • oxygen oxide • nitrogen nitride • sulfur sulfide • fluorine fluoride • chlorine chloride • bromine bromide Practice • CO2 carbon dioxide • N2O dinitrogen monoxide • SCl5 sulfur pentachloride • H2O dihydrogen monoxide • CCl4 carbon tetrachloride

18. Naming when the formula starts with a metal MgCl2 FeCl2 • Name the first element • Check if this element is a transition metal or Tin or Lead • no just name the second part • yesassign the negative oxidation state first then determine the positive • write it as a Roman Numeral

19. CuSO4 Copper II sulfate Ba(OH)2 Barium hydroxide Al2S3 aluminum sulfide CuCl copper I chloride CuCO3 copper II carbonate Remember: You only need a roman numeral if you have a transition metal, or Sn or Pb….but not Zn or Ag Practice

20. Naming polyatomic ion - element compounds NH4Cl • No prefixes • No roman numerals just name it! • Practice NH4F ammonium fluoride (NH4)2S ammonium sulfide

21. Just name them! Practice (NH4)2SO4 ammonium sulfate (NH4)2CrO4 ammonium chromate (NH4)3PO4 ammonium phosphate Naming compounds with 2 polyatomic ions

22. The End