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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 Examples
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 PO3
3-
Chlorate ClO3 Dichromate Cr2O7
2-
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 FormulasName 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
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