PROPERTIES OF IONIC AND MOLECULAR COMPOUNDS

WHAT IS AN IONIC COMPOUND? Neutral compound Neutral compound Formed from a metal and a non-metal Formed from a metal and a non-metal Metal is a cation (positively charged) Metal is a cation (positively charged) Exception: Ammonium ion NH 4 + Exception: Ammonium ion NH 4 + Non-metal is an anion (negatively charged) Non-metal is an anion (negatively charged) Ionic compounds are polar Ionic compounds are polar Electrons are transferred! Electrons are transferred!

PROPERTIES OF IONIC COMPOUNDS Form crystals Form crystals High melting and boiling points High melting and boiling points Hard and brittle Hard and brittle Conduct electricity ONLY WHEN DISSOLVED IN WATER! Conduct electricity ONLY WHEN DISSOLVED IN WATER! Do NOT conduct electricity in their solid form Do NOT conduct electricity in their solid form

IONIC COMPOUND FORMULA WRITING THEY ARE NEUTRAL AND HAVE NO CHARGE! THEY ARE NEUTRAL AND HAVE NO CHARGE! Balance out charges from cation and anion to form a neutral compound Balance out charges from cation and anion to form a neutral compound Find common factor between charges Find common factor between charges Superscripts tell you the charge Superscripts tell you the charge Subscripts tell you the number of atoms Subscripts tell you the number of atoms Polyatomic ions = Ions formed from more than one element Polyatomic ions = Ions formed from more than one element Treat polyatomic ions as a group or whole unit 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 Need parentheses ONLY when more than one polyatomic ion unit is required to make compound neutral Al +3 SO 4 -2 Al 2 (SO 4 ) 3

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

PRACTICE Na + Cl - Ca +2 PO 4 -3 Aluminum nitrate Ammonium Sulfate Magnesium chloride

WHAT IS A MOLECULAR COMPOUND? Neutral compound Neutral compound Formed from TWO NON-METALS! Formed from TWO NON-METALS! Can be polar or non-polar Can be polar or non-polar ELECTRONS ARE SHARED! ELECTRONS ARE SHARED! Lewis Dot Lewis Dot

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

MORE EXAMPLES OF MOLECULAR COMPOUNDS

MOLECULAR COMPOUND FORMULA WRITING Draw Lewis dot structure Draw Lewis dot structure SHARE ELECTRONS SO EACH ELEMENT HAS 8! SHARE ELECTRONS SO EACH ELEMENT HAS 8! OCTET RULE OCTET RULE

LET’S PRACTICE!

MOLECULAR COMPOUND NAMING Use Greek prefixes Use Greek prefixes First element is still just the name of the element First element is still just the name of the element Second element ends in “ide” Second element ends in “ide” If first element is only one, mono not needed! If first element is only one, mono not needed! If second element is one, mono IS needed. If second element is one, mono IS needed.

PRACTICE CO 2 H 2 O SF 6 Carbon monoxide Silicon dioxide Dinitrogen tetroxide