Compounds Element = 1 type of atom Compound = more than 1 type of atom (over 8 million) Chemical Bond = glue that links atoms together in a compound

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1 Compounds Element = 1 type of atom Compound = more than 1 type of atom (over 8 million) Chemical Bond = glue that links atoms together in a compound Ionic Compounds Ionic Bonds = atoms switch e- forming ions. + & - ions attract each other. *STRONG BOND* makes for high MP & BP Also called Salts Ionic bonds Made of + & - ions Electrically neutral Usually made of a metallic and nonmetallic element or polyatomic ions Representative particle is called a formula unit Usually crystalline solids at room temperature Have high melting points & boiling points Conduct electricity well in the molten state or when dissolved in a solution. Octet Rule =Atoms are most stable with the e- configuration of a noble gas (w/ 8 valence electrons) Monatomic Ions ± o Cation (metals) = + ions (lost e-) ----> Use the name of the metal. Ex: Ca +2 = calcium o Anion (nonmetals) = - ions (gained e-) --> Change the ending to ide. Ex: F -1 = fluoride; N -3 = nitride Polyatomic Ions = tightly bound group of atoms that behave as a unit and carry a charge **NEVER CHANGE SUBSCRIPT in these ions****

2 Writing Formulas for Ionic Compounds 1. Write formula for cation 2. Write anion formula 3. Combine enough cations with enough anions to give a total charge of zero * Trick = Swap charges as subscripts and don t write charges when ions are combined 4. Use the simplest (smallest/reduced) cation to anion ratio possible 5. Cations 1 st, anions last 6. Use parenthesis when multiplying a polyatomic ion 7. Leave off subscript 1 Ex: WS#1: * Calcium bromide * Potassium sulfide * Cesium arsenide WS #2 * Tin (IV) oxide * Gallium chromate *Magnesium hydroxide * Aluminum sulfate Naming Ionic Compounds Stock System (New) Name the cation (always 1 st ) transition metals + Pb and Sn: Must include a charge ( in Roman Numeral form) for cations with multiple charges 1A, 2A, 3A, Ag +, Cd +2, Zn +2 always have same charge (NO ROMAN NUMERALS) Name anion = change ending to ide if it is not a polyatomic ion ( ite, ate, or ide) Ex: Na 2 S = MgCl 2 = NaClO = Sn 3 (PO 3 ) 2 = Sn(SO 3 ) 2 = *know anion - determine positive charge by equaling anion charge Classical Method Only for cations with multiple charges Use the classical name of element a. Suffix = -ous = name with lower charge b. Suffix = -ic = name with higher charge Disadvantage = does not tell charge of cation only larger or smaller Ex: Fe 3 N 2 FeN

3 Writing Ionic Equations 1) Write the symbol of the cation 2) Write a + sign 3) Write the symbol of the anion 4) Write an arrow to the right ( ) 5) Write the correct formula of the compound 6) Balance the ions on the left with the ions in the formula using coefficients only. EX: ionic equation for CaCl 2 Ca Cl -1 CaCl 2 2NH SO 4-2 (NH 4 ) 2 SO 4 Molecular Compounds Made of molecules an electrically neutral group of atoms that act as a unit Can have 2 to thousands of atoms Same element composition and properties as the entire compound A.K.A. = covalent compounds Covalent bonds = sharing e- (weaker than ionic) Ex: H 2 O, CO 2, C 6 H 12 O 6, NH 3, CH 4 Representative Particle Electrical Conductivity State at Room Temperature Other Names Made up Of Molecular Compounds Molecule Poor Mostly liquids and gases Covalent compounds 2 or more nonmetals or metalloids Ionic Compounds Formula unit Good molten or dissolve Solid Salts Has a Metal &/or Polyatomic Ion (has a cation other than H)

4 Naming Molecular Compounds 1. Write name of 1 st nonmetal 2. Write name of 2 nd nonmetal change ending to ide 3. Insert prefix into name to reflect subscripts Mono = 1 Di = 2 Tri = 3 Tetra = 4 Penta = 5 Hexa = 6 Hepta = 7 Octa = 8 Nona = 9 Deca = Never start a name with mono- 5. Drop the a or o off the prefix with Oxygen N 2 S 5 = Dinitrogen pentasulfide S 2 Cl 2 = Disulfur dichloride SF 6 = Sulfur hexafluoride NO 2 = Nitrogen dioxide Writing Molecular Formulas 1. Symbol of 1 st element, add pre- as subscript 2. Do same for 2 nd element How Can You Tell If A Compound Is Ionic Or Molecular? Made of only 2 types of nonmetal or metalloids = molecular (use prefixes) If a metal or a polyatomic ion = ionic (no prefixes) Naming Acids Acids - All have H +, so the name is based on the anion (- part) Anion ending -ide -ite Rule Example Hydro(stem)ic HCl has Chloride =Hydrochloric a HBr has bromide = Hydrobromic (stem)ous HNO 2 has nitrite = nitrous HClO 2 has chlorite = chlorous -ate (stem)ic H 3 PO 4 has phosphate = phosphoric H 2 SO 4 has sulfate = sulfuric HNO 3 has nitrate = nitric *S compounds use (sulfur) as the root * P compounds use (phosphor) as the root Formulas of Acids Use H + as the cation. Determine the anion from the name. Combine enough of each to balance out the charge. Ex: anion ions formula hydronitric nitride H + N -3 H 3 N

5 Phosphorous phosphite H + -3 PO 3 carbonic carbonate H + -2 CO 3 H 3 PO 3 H 2 CO 3 Bases are named like any other ionic compound: Cation Anion Formulas are