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Naming Binary Ionic Compounds
What is a binary ionic compound?
• IONIC COMPOUND– Formed from ionic bonds– Metal and nonmetal
• Left of stepline on PT=metal
• Right of stepline on PT=nonmetal
• BINARY– Prefix “bi” means 2– A binary compound
contains teo different kinds of elements
A Common Example
• NaCl– Na=sodium=metal=cation– Cl=chlorine=nonmetal=anion– Two elements joined by an ionic bond
• Na loses electron to form positive ion• Cl gains electron to form negative ion• Ions are attracted by electrostatic charges
How do we name it?Name the metal
Na
Sodium
Name the non-metal with an “-ide” ending
Cl
ChlorineChlorineChloride
NaCl
sodium chloride
Is it always this easy?
• Almost…but not quite!• Group 1,2, and 13 metals have charges
determined by their position on the periodic table…1+, 2+. 3+
• Ag is always 1+• Cd is always 2+• Zn is always 2+
Transition metals
• The charges of transition metal cations (and a few others under the stepline) vary
• The charge of these cations must be calculated to balance the negative charge of the anions involved
CuS is copper (II) sulfide• Copper can have different charges• What is it paired up with and what ratio is needed to have a net
charge of zero?• The anion is sulfide
– Sulfur produces a sulfide ion which is 2-. (You know this from the periodic table.)
• The cation is copper– One Cu is present, so its charge must be 2+ to balance the 2- charge from
the S
• Name cation, show charge as Roman numeral in parentheses, name anion with -ide ending.
Fe2S3 is iron (III) sulfide
• Sulfide is 2- (from its position on periodic table)• There are 3 sulfide 3 x 2- = 6-
• Iron can have different charges• 2 iron ions balance a 6- charge• 2 x ? = 6+• Iron’s charge in this compound is 3+• Name cation, show charge as Roman numeral in parentheses,
name anion with -ide ending.
• Reverse criss-cross!