Chemical Formulas Chapter 5, pages 106-140

Chemical Formulas Chemical formula - a symbolic representation of chemical compounds; contains: elements in compound (symbols) # of atoms in each element NaCl – sodium-one atom & chlorine-one atom H2O – Hydrogen-2 atoms & oxygen-one atom

Types of Chemical Formula Ionic Giving and Taking of Electrons Covalent Share of electrons

Types of Chemical Formulas Ionic – metal and non-metal → transfer of electrons (e-) Cation – lose e-, + charge (metals) Anion – gain e-, - charge (non-metals) H+ is the exception to this rule! H – acts like a metal – has + charge

Types of Ions There are two types on Ions Monatomic Polyatomic

Monatomic Ions Ions that are composed of only one element Some elements may only form 1 ion Examples H+ (Hydrogen Ion) Cl- (Chloride Ion) Li+ (Lithium Ion) Some Elements may form 2 or more ions Cu+ Copper(I) or Cuprous Ion Cu2+ Copper(II) or Cupric Ion

Common Monatomic Cations 1+ Charge 2+ Charge 3+ Charge Hydrogen H+ Barium Ba2+ Aluminum Al3+ Potassium K+ Calcium Ca2+ Chromium Cr3+ Lithium Li+ Cobalt(II) Co2+ Iron(III) Fe3+ Sodium Na+ Copper(II) Cu2+ Cesium Cs+ Iron(II) Fe2+ Silver Ag+ Lead Pb2+ Copper(I) Cu+ Magnesium Mg2+

Common Monatomic Anions 1- Charge 2- Charge 3- Charge Bromide Br- Oxide O2- Nitride N3- Fluoride F- Sulfide S2- Chloride Cl- Iodide I-

Types of Ionic Compounds There are 2 types of Ionic compounds: Binary Ionic Compounds Ternary Ionic Compounds

Naming Binary Ionic Compounds monoatomic + monoatomic (one atom + one atom) 1 cation (+) + anion (-) Examples zinc oxide Zn + O= ZnO magnesium chloride Mg + Cl= MgCl2 aluminum oxide Al + O= Al2O3 Naming Binary Ionic Compounds Begin with name of Cation Normally elements name End with name of Anion Normally has –ide or –ate ending If cation has multiple charges, you must indicate using roman numerals (Stock Naming System)

Polyatomic Ions Polyatomic Ions are ions that are composed of two or more different elements Again you have Positive Polyatomic Ions= Negative Polyatomic Ions= We will only talk about one positive polyatomic ion which is ammonium ion (NH4+1)

Common Monatomic Anions 1- Charge 2- Charge 3- Charge Acetate Carbonate O2- Phosphate PO43- Bicarbonate HCO3- Chromate CrO42- Phosphite PO33- Chlorate ClO3 Dichromate Cr2O72- Cyanide CN Oaxlate C2O42- Nitrate N03 Sulfite SO32- Nitrite NO2 Sulfate SO42- Hydroxide OH-

Ternary Ionic Compounds Compounds that contain 3 or more ions One must be a polyatomic ion Cation + Polyatomic Anion = Ternary Ion Examples Potassium Nitrate K + NO3= KNO3 Naming Ternary Ionic Compounds Begin with name of Cation Normally elements name End with name of Anion Normally has –ide or –ate ending

Writing Binary and Ternary Formulas Name Cation Anion Equation Sodium Chloride Iron(III) Oxide Iron(II) Nitrate Copper(II) Sulfate

What about the Roman Numerals Two Different Naming Systems Stock System Roman Numerals refer to Charge of the Cation or Anion Newer, for the Lazy and Underachievers Traditional System -ous or –ic Ending Older, for the sophisticated and over achievers

Traditional vs. Stock Cation Traditional Name Stock Name Fe 3+ Cu 2+ Pb 4+ Point is to be careful when using the traditional and stock ways Stock May be more useful to you Traditional is important to know for MSDS