Describing Chemical Reactions Ch 11 – Chemical Reactions Describing Chemical Reactions

Formed by TRANSFERRING e-s TYPES OF BONDING IONIC Formed by TRANSFERRING e-s COVALENT Formed by SHARING e-s METALIC BONDING Formed of positive metal cations in a “sea” of valence electrons

Bond Types Ionic bonding – Metal & Nonmetal Covalent bonding – Nonmetal & Nonmetal Metallic – Metal & Metal

Naming Ionic Compounds Formula Ions Name KCl Mg(NO3)2 CuCl2 NaBr Na2CO3 FeCl3 ZnS   K+ & Cl- Potassium Chloride Mg2+ & NO3- Magnesium Nitrate Copper (II) Chloride Cu2+ & Cl- Cupric Chloride Na+ & Br- Sodium Bromide Na+ & CO32- Sodium Carbonate Iron (III) Chloride Fe3+ & Cl- Ferric Chloride Zn2+ & S2- Zinc Sulfide

Molecular Nomenclature Prefix System (binary compounds) Less electronegative atom comes first. 2. Add prefixes to indicate # of atoms. Omit mono- prefix on first element. 3. Change the ending of the second element to -ide. most

Molecular Nomenclature PREFIX mono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca- NUMBER 1 2 3 4 5 6 7 8 9 10

Naming Covalent Binary Compounds diphosphorus pentoxide P2O5 = CO2 = carbon dioxide CO = carbon monoxide N2O = dinitrogen monoxide phosphorous pentachloride = PCl5 dinitrogen tetrahydride = N2H4 dichlorine heptaoxide = Cl2O7 iodine dioxide = IO2

Signs of a Chemical Reaction Evolution of heat and light Formation of a gas Formation of a precipitate Color change

Law of Conservation of Mass mass is neither created nor destroyed in a chemical reaction total mass stays the same atoms can only rearrange 4 H 2 O 4 H 2 O 36 g 4 g 32 g

Chemical Equations A+B C+D REACTANTS PRODUCTS

Chemical Equations p. 323

2H2 (g) + O2 (g)  2H2O (g) Writing Equations Identify the substances involved. Use symbols to show: How many? - coefficient Of what? - chemical formula In what state? - physical state Remember the diatomic elements.

Writing Equations 2 Al + 3 CuCl2  3 Cu + 2 AlCl3 (s) (aq) (s) (aq) Two atoms of aluminum react with three units of aqueous copper(II) chloride to produce three atoms of copper and two units of aqueous aluminum chloride. How many? Of what? In what state? 2 Al + 3 CuCl2  3 Cu + 2 AlCl3 (s) (aq) (s) (aq)

Describing Equations Describing Coefficients: individual atom (element) = “atom” covalent substance = “molecule” ionic substance = “unit” or “formula unit” 3CO2 2Mg 4MgO 3 molecules of carbon dioxide 2 atoms of magnesium 4 units of magnesium oxide

Zn(s) + 2HCl(aq)ZnCl2(aq) + H2(g) Describing Equations Zn(s) + 2HCl(aq)ZnCl2(aq) + H2(g) How many? Of what? In what state? One atom of solid zinc reacts with two molecules of aqueous hydrochloric acid of aqueous zinc chloride to produce one formula unit molecule of hydrogen gas. and one

Describing Equation Practice 2Al (s) + 3CuCl2 (aq)  3Cu(s) + 2 AlCl3(aq) Two atoms of solid Aluminum and 3 three unit of aqueous copper chloride react to form three solid atoms copper and two aqueous compounds of aluminum chloride.

Describing Equation Practice 2Mg (s)+ 2N2 (g)  2MgN(s) Two atoms of solid magnesium and Two molecule of nitrogen gas react to form three solid compounds of magnesium nitride

Describing Equation Practice 2Na (s)+ 2H2O (l)  2H2 (g) + 2NaOH (aq) Sodium hydroxide Two atoms of solid sodium and two compounds of liquid water react to form two molecules of hydrogen gas and two compounds of a solution sodium hydroxide.