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