What are they made of?
Binary
Ionic
Example sodium, Na+ metal chlorine, Cl- non-metal
metal ion + non-metal ion
2 elements
REMEMBER !
• Metals tend to Lose electrons and become positive ions (cations).
• Non-metals tend to gain electrons and become negative ions (anions).
Crystal Lattice Structure • Each electron which Sodium atom lost, is
grabbed by Fluorine atom. • There same number of Na+ and F- ions,
their ratio is 1:1, but • ions do not form molecules. Instead, they
are tightly packed in crystals with alternative + and – ions.
Chemical Formula
• Ex 1: One Sodium for One Fluorine– NaF
• Ex2 : One Aluminum for Three Chlorine – NaCl3
• Subscript 3 in the formula indicates that it takes 3 Cl atoms to 1 Al atom.
• With the right subscript, the overall charge of the compound is zero.
Naming Ionic Bonds from Formula
1) Write name of metal
2) Write name of non-metal
3) Non-metal suffix = IDE
sodiumsodium chlorinesodium chloride
NaCl
Cations and Anions
Common Simple Cations and Anions
Cation Name Anion Name*
H 1+ hydrogen H 1- hydride Li 1+ lithium F 1- fluoride Na 1+ sodium Cl 1- chloride K 1+ potassium Br 1- bromide Cs 1+ cesium I 1- iodide Be 2+ beryllium O 2- oxide Mg 2+ magnesium S 2- sulfide Al 3+ aluminum Ag 1+ silver
*The root is given in color.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 86
Writing Chemical Formulas for Ionic Compounds.
Points to note:The metal ion/cation is always firstThe nonmetal ion/anion is always written secondSteps:1. Write the chemical symbols for each element (metal first)2. Write the ionic charge above each element 3. Criss-cross the NUMBERS (not the signs) and write them
as subscripts
Example: Aluminum Chloride
Step 1:
Step 2:
Step 3: 1 3
Step 4: AlCl3
Formula from Name: Criss-Cross Rule
Al Cl
Al Cl
3+ 1-
write out name with space
write symbols & charge of elements
criss-cross charges as subsrcipts
combine as formula unit(“1” is never shown)
Aluminum Chloride
Example: Aluminum Oxide
Step 1:
Step 2:
Step 3: 2 3
Step 4: Al O3
Criss-Cross Rule
Al O
Al O
3+ 2-
write out name with space
write symbols & charge of elements
criss-cross charges as subsrcipts
combine as formula unit
Aluminum Oxide
2
Example: Magnesium Oxide
Step 1:
Step 2:
Step 3: 2 2
Step 4: Mg2O2
Criss-Cross Rule
Mg O
Mg O
2+ 2-
Magnesium Oxide
Step 5: MgO(reduce subscripts to lowest ratio)
HINTS:• Criss-cross rule will help you to figure
out the right subscript in the compound formula
• Ignore subscript if it is 1• Subscripts do not have signs: it’s a
number of ions!• Final formula shall not indicate charge
on top• Reduce subscripts, go by lower terms
Naming Binary Compounds
Formula Name
1 BaO ____________________
2 ________________ sodium bromide
3 MgI2 ____________________
4 KCl ____________________
5 ________________ strontium fluoride
6 ________________ cesium fluoride
barium oxide
NaBr
magnesium iodide
potassium chloride
SrF2
CsF
Multivalent Binary CompoundsContaining a Metal (Variable Oxidation Number) and Non Metal
To name these compounds (stock system): 1. Write the name of the metal2. Followed by Roman numerals in parentheses to indicate the oxidation number of the metal3. Write the name of the nonmetal, with its ending replaced by the suffix –ide.
Examples IUPAC System
FeCl2 Iron (II) chloride
SnO Tin (II) oxide
FeCl3 Iron (III) chloride
SnO2 Tin (IV) oxide
Common Multivalent Cations
Ion IUPAC System Fe 3+ iron (III) Fe 2+ iron (II) Cu 2+ copper (II) Cu 1+ copper (I) Au 3+ gold (III) Au 1+ gold (I) Sn 4+ tin (IV) Sn 2+ tin (II) Pb 4+ lead (IV) Pb 2+ lead (II) Cr 3+ chromium (III) Cr 2+ chromium (II) Ni 3+ Nickel (III) Ni 2+ Nickel (II)
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 90
Naming Binary CompoundsFormula Name
1 SnF4 ____________________
2 HgO ____________________
3 ________________ copper (II) fluoride
4 ________________ copper (I) sulfide
5 Cr2O3 ____________________
6 ________________ lead (IV) oxide
tin (IV) fluoride
PbO2
mercury (II) oxide
CuF2
Cu2S
chromium (III) oxide
Top Related