Chemical names and formulas

• Chemical formula


  Indicates the relative number of atoms of each kind in a chemical compound
• Molecular compound formula


  Reveals the number of atoms of each element contained in a single molecule of the compound
• Ionic compound formula


  Represents one formula unit - the simplest ratio of the compound's positive ions (cations) and its negative ions (anions)
• Monatomic ion


  Ion formed from a single atom
• Monatomic ions


  • Many main-group elements can lose or gain electrons to form ions
  • Some main-group elements tend to form covalent bonds instead of forming ions (e.g. carbon and silicon)
• Naming monatomic cations


  Identified by the element's name
• Naming monatomic anions


  The ending of the element's name is dropped, and the ending -ide is added to the root name
• Common monatomic ions


  • Cations: K+, Mg2+
  • Anions: F-, N3-
• Binary compound


  Compounds composed of two elements
• Binary ionic compound


  The total numbers of positive charges and negative charges must be equal
• Determining formula of binary ionic compound

  1. Write the symbols for the ions side by side

  2. Cross over the charges by using the absolute value of each ion's charge as the subscript for the other ion

  3. Check the combined positive and negative charges to see if they are equal
• Naming binary ionic compounds


  The name of the cation is given first, followed by the name of the anion

  
• Binary ionic compounds


  • Zinc iodide (ZnI2)
  • Zinc sulfide (ZnS)
• Stock system of nomenclature

  • Used to distinguish ions formed by elements that can form multiple cations with different charges
  • Uses a Roman numeral to indicate an ion's charge
• Cr3+


  Chromium(III) ion
• 1. 
     

  Fluoride ion
• Naming binary ionic compounds

  1. Write the symbols for the ions side by side, with the cation first

  2. Cross over the charges to give subscripts

  3. The subscripts give the charges of the ions

  4. The largest common factor of the subscripts is the smallest whole number ratio of the ions

  5. The formula is written

  
• Chromium(III) fluoride


  The name of the compound where chromium forms a 3+ ion
• Oxyanion


  Polyatomic ion that contains oxygen
• Nitrate (NO3-)


  Oxyanion with the greater number of oxygen atoms
• Nitrite (NO2-)


  Oxyanion with the smaller number of oxygen atoms
• Hypochlorite (ClO-)


  Oxyanion with one fewer oxygen atom than the -ite anion
• Chlorite (ClO2-)


  Oxyanion with the -ite ending
• Chlorate (ClO3-)


  Oxyanion with the -ate ending
• Perchlorate (ClO4-)


  Oxyanion with one more oxygen atom than the -ate anion
• Naming compounds containing polyatomic ions

  1. Cross over the charges to give subscripts

  2. Add parentheses around the polyatomic ion if necessary
• Tin(IV) sulfate


  The name of the compound where tin forms a 4+ ion and the polyatomic sulfate ion is present
• Molecular compounds


  Composed of individual covalently bonded units or molecules
• Stock system for naming molecular compounds

  Uses prefixes to indicate the number of atoms
• Molecular compound names


  • Carbon tetrachloride
  • Carbon monoxide
  • Carbon dioxide
• Naming binary molecular compounds

  1. The first word indicates the element that comes first in the formula

  2. The second word indicates the element that comes second in the formula, with a prefix to indicate the number of atoms
• Diarsenic pentoxide


  The name of the compound As2O5
• Oxygen difluoride


  The name of the compound OF2
• Covalent-network compounds


  Covalent compounds that do not consist of individual molecules, but rather a three-dimensional network of covalently bonded atoms
• Acid


  A molecular compound, either a binary acid or an oxyacid
• Binary acid


  An acid consisting of hydrogen and a halogen
• Oxyacid


  An acid containing hydrogen, oxygen, and a third element (usually a nonmetal)
• Hydrochloric acid


  A water solution of the molecular compound hydrogen chloride, HCl
• Sulfate, nitrate, phosphate


  Polyatomic ions produced by the loss of hydrogen ions from oxyacids
• Salt


  An ionic compound composed of a cation and the anion from an acid