Properties of Ionic and molecular compounds

What is an Ionic compound? Neutral compound Formed from a metal and a non-metal Metal is a cation (positively charged) Exception: Ammonium ion NH4+ Non-metal is an anion (negatively charged) Ionic compounds are polar Electrons are transferred! Bond is easily broken Can typically be broken by dissolving the compound in water

Properties of Ionic compounds Form crystals High melting and boiling points Hard and brittle Conduct electricity ONLY WHEN DISSOLVED IN WATER! Do NOT conduct electricity in their solid form

Examples of ionic compounds TELL ME SOME!

Ionic compound formula writing THEY ARE NEUTRAL AND HAVE NO CHARGE! Balance out charges from cation and anion to form a neutral compound Find common factor between charges Criss-cross charges (make sure they are reduced) Superscripts tell you the charge Subscripts tell you the number of atoms Polyatomic ions = Ions formed from more than one element Treat polyatomic ions as a group or whole unit Need parentheses ONLY when more than one polyatomic ion unit is required to make compound neutral Al+3 SO4-2 Al2(SO4)3

Ionic compound naming Cations are written FIRST followed by the anions Cations are named by the name of the element Ex: name of Sodium’s ion is…you guessed it, SODIUM ION Anions are named by the name of the element but… They end in –ide Ex: Chlorine ion = CHLORIDE Cations that form multiple charges need to have the Roman numeral in the name Ex: Iron (II) chloride

Oxygen is a Special Case Atom bonded to 3 or 4 oxygens Ends in –ate Nitrate (NO3-1) Phosphate (PO4-3) Sulfate (SO4-2) Atom with 1 less oxygen than the –ate form Ends in –ite Nitrite (NO2-1) Phosphite (PO3-3) Sulfite (SO3-2) Hypo- and Per- prefixes ClO3-1 (Chlorate) ClO2-1 (Chlorite) ClO-1 (Hypochlorite) ClO4-1 (Perchlorate)

What is a Molecular Compound? Neutral compound Formed from TWO NON-METALS! Can be polar or non-polar ELECTRONS ARE SHARED BETWEEN THE 2 (or more) ELEMENTS! Lewis dot structure helps with representing the bond(s)

Properties of molecular compounds Most have LOW melting and boiling points Tend to be soft and/or flexible State of matter of most molecular compounds More flammable than ionic compounds Carbon, hydrogen, oxygen Don’t dissolve well in water (usually) and are non-conductive

More examples of molecular compounds

Molecular compound formula writing Draw Lewis dot structure SHARE ELECTRONS SO EACH ELEMENT HAS 8! OCTET RULE

Let’s practice!

Molecular compound naming Use Greek prefixes First element is still just the name of the element Second element ends in “ide” If first element is only one, mono not needed! If second element is one, mono IS needed. CO2 H2O SF6 Carbon dioxide Dihydrogen monoxide Sulfur hexafluoride

Types of Molecular bonds Different bonds Single bond 1 line 2 electrons are shared Double bond 2 lines 4 electrons are shared Π-bond Triple bond 3 lines 6 electrons are shared

Types of Molecular Bonds cont. Two types of molecular bonds Covalent bond Electrons are shared equally All diatomic molecules Polar covalent bond Electons are shared unequally More electronegative element pulls electrons toward itself Dipole

Predicting the type of bond The Rules of Predicting the Bonds If the difference between 2 elements is 0 to 0.5 Nonpolar covalent If the difference between 2 elements is 0.6 to 1.6 Polar covalent If the difference between 2 elements is greater than 1.6 Ionic

Saturated and Unsaturated Bonds Both involve covalent bonds Saturated Bonds No double or triple bonds in the chain of carbons Unsaturated Bonds Double or triple bonds exist in the chain of carbons