Unit_1_1_Naming_Compounds_and_Chemical_Balancing (1).ppt

Unit 1 Reactivity  UNIT 1 Reactivity Key Concept : Change Related Concept : Consequences Global context : Globalization and Sustainability Exploration : Human impact on the environment  Review: Naming Compounds Writing Formulas and Equations  Learning Objecti...

Unit 1 Reactivity  UNIT 1 Reactivity Key Concept : Change Related Concept : Consequences Global context : Globalization and Sustainability Exploration : Human impact on the environment  Review: Naming Compounds Writing Formulas and Equations  Learning Objectives Name simple chemical compounds (ionic, covalent and polyatomic) Write the chemical formula of simple compounds Analyze chemical formula to deduce elemental composition and the ratio of atoms  Learning Objectives Balance a chemical equation using the number of atoms in the reactants and product Write and balance a symbolic chemical equation from a word equation or description of an experiment  Naming Ionic Compounds  Ionic compounds are combinations of positive and negative ions.  In writing the chemical formula the positive ion is written first, It is then followed by the name of the negative ion.  Monatomic anions end in ide. Special endings apply for polyatomic ions  Examples NaCl Sodium chloride  Names of Polyatomic Ions with Oxygen Polyatomic ions usually contain oxygen in addition NO2- Nitrite to another element. NO3- Nitrate Normally they have PO33- phosphite a negative charge. PO43- phosphate They end in either "ate" or "ite" SO32- sulfite depending on the SO42- sulfate number of oxygen atoms present.  Polyatomic Ion -- Exceptions Most polyatomic ions contain oxygen Their names end in “ite” or “ate”. There are several exceptions OH- hydroxide CN- cyanide SCN- thiocyanate  Elements with Multiple Cations When an element can form more than one cation a Roman numeral is used to distinguish the oxidation state of the compound. Iron, Tin, Lead, Copper, and are common elements with more than one cation. Examples 1. PbSO4 = lead (II) sulfate This compound is formed from Pb2+ and SO42- 2. Pb(SO4)2 = lead (IV) sulfate This compound is formed from Pb4+ and SO42- 3. Fe(OH)2 = iron (II) hydroxide This compound is formed from Fe2+ and OH- 4. Fe(OH)3 = iron (III) hydroxide This compound is formed from Fe3+ and OH- Examples of Ionic Compounds 1. NaCl = Sodium chloride 2. ZnF2 = Zinc fluoride 3. KOH = Potassium hydroxide 4. Ca(NO3)2 = Calcium nitrate 5. BaSO3 = Barium Sulfite 6. Al2(SO4) 3 = Aluminum sulfate 7. Ca3(PO3)2 = Calcium phosphite 8. NH4Cl = Ammonium chloride 9. (NH4)2CO3 = Ammonium carbonate Naming Covalent Compounds  When naming covalent compounds, the name of the first element in the formula is unchanged.  The suffix “-ide” is added to the second element.  Often a prefix to the name of the second element indicates the number of the element in the compound  Examples: SF6 – sulfur hexafluoride P4O10 – tetraphosphorous decoxide CO – carbon monoxide Acids When many hydrogen compounds are dissolve in water they take on the form of an acid. Special rules apply to acids. The “ite” suffix becomes “ous” and the “ate” suffix becomes “ic” HCl Hydrochloric Acid Cl- Chloride HNO2 Nitrous Acid NO2- Nitrite HNO3 Nitric Acid NO3- Nitrate H2SO3 Sulfurous Acid SO32- Sulfite H2SO4 Sulfuric Acid SO42- Sulfate H3PO3 Phosphorous Acid PO33- Phosphite H3PO4 Phosphoric Acid PO43- Phosphate H2CO3 Carbonic Acid CO32- Carbonate Base  Examples 1. Na+ and Cl- = NaCl 2. Zn2+ and Br- = ZnBr2 3. K+ and OH- = KOH 4. Ca2+ and OH- = Ca(OH)2 5. Fe2+ and SO42- = FeSO4 6. Fe3+ and SO42- = Fe2(SO4) 3 7. Ca2 + and PO43- = Ca3(PO4)2 8. NH4+ and Cl- = NH4Cl 9. NH4+ and CO32- = (NH4)2CO3 Chemical Reactions Chemical Reactions  Reactants and Products In the chemical reaction Zn + 2 HCl  ZnCl2 + H2 Reactants Products This shorthand way of describing a chemical reaction is known as a chemical equation The starting materials are shown on the left and are known as reactants The substances formed are shown on the right and are known as the products Balancing a Chemical Reaction A proper chemical reaction must be balanced Zn + 2 HCl  ZnCl2 + H2 Reactants Products Each element must appear on both sides of the arrow and equal number of times Chemical reactions can be balanced by inserting numbers in front of formulas. These numbers are called coefficients  Balancing Chemical Reactions Most simple equations can be balanced by inspection Example: Balance the following equation BaCl2 + K3PO4  Ba3 (PO4)2 + KCl There are 3 Ba on the right so we need coefficient of 3 in front of BaCl2 There are 2 PO4 on the right so we need a coefficient of 2 in front of K3PO4. This leaves 6 K on the left so we need a coefficient of 6 in front of the KCl on the right The balanced equation is 3 BaCl2 + 2 K3PO4  Ba3 (PO4)2 + 6 KCl Balancing Chemical Reactions An equation is balanced when there are the same number and kind of atoms on both sides of the arrow 3 BaCl2 + 2 K3PO4  Ba3(PO4)2 + 6 KCl Reactants (Left) Products (Right) Ba 3 Ba 3 Cl 3x2=6 Cl 6 K 2x3= 6 K 6 P 2 P 2 O 2x4=8 O 2x4 =8 Balance the following chemical reaction  State Symbols State symbols are often added to chemical equations. CaCO3 (s) + 2 HCl (aq)  CaCl2 (aq) + CO2 (g) + H2O (l) Symbols (s) Solid (l) Liquid (g) Gas (aq) Aqueous (Water Solution)  Diatomic Molecules Certain elements H2 Hydrogen Have exist as diatomic N2 Nitrogen No molecules in nature F2 Fluorine Fear O2 Oxygen Of I2 Iodine Ice Cl2 Chlorine Cold Br2 Bromine Beer