Ionic Bonds Slide Show #1 Atoms are neutral • The # of protons = the # of electrons. • + charges are equal to – charges. • But, if an electron leaves, the atom becomes more positive. electrons < protons • When an atom gains an electron it becomes more negative electrons > protons • We call an atom that is charged an ion! Electron Transfer • Atoms with 5, 6, or 7 valence electrons do not have enough to make a stable 8. • Atoms with 1,2, or 3 valence electrons can transfer their electrons to these atoms. • In any case the goal is to become stable! Big Idea! • Metals give electrons! (become positive) • Nonmetals receive electrons! (become negative) Ionic Bonding • Sodium can give up its electron (becomes +). • Chlorine can accept this electron (becomes -) • + & - attract and create an ionic bond. • Sodium Chloride is table salt and is now neutral! Ions and their charges Name Charge Ionic form Lithium +1 Li+1 Sodium +1 Na+1 Potassium +1 K+1 Calcium +2 Ca+2 Magnesium +2 Mg+2 Aluminum +3 Al+3 Fluorine -1 F-1 Chlorine -1 Cl-1 Oxide -2 O-2 Sulfide -2 S-2 Ionic Bonds – Some facts! • Ionic compounds dissolve easily in water. • Ionic solutions (i.e. salt water) easily conduct electricity. • Ionic compounds form crystalline solids with high melting temperatures. Naming Ionic Compounds Positive Ion first (usually metal) Negative Ion last (usually nonmetal) • If the negative ion is an element, use –ide • MgO is Magnesium Oxide • NaCl is Sodium Chloride • KS is Potassium Sulfide, "Perhaps one of you gentlemen would mind telling me just what is outside the window that you find so attractive...?" How to write an ionic formula • Write the charges for metal & non-metal • Cross the charge of the metal to the subscript of the non-metal • Cross the charge of the non-metal to the subscript of the metal. • Now, simplify!