1. Ch. 7: Chemical Formulas and Compounds
7.1 Chemical Names and Formulas

2. Chemical Formulas molecular compound ionic compound
number of atoms of each element contained in a single molecule of the compound
NO2, CH2Cl2,
ionic compound
***Contains a metal typically!
represents one unit
simplest ratio of the compounds anions and cations
MgO, Mg(OH)2, NH4Br

3. Monatomic Ions ions formed from a single atom
Not all representative elements easily form ions
Some atoms form covalent bonds instead
Others form ions without noble gas configurations
d and p-block metals
many form 2+ or 3+, some +1 or +4

4. Naming Monatomic Ions cations anions positive ion negative ion
written first in formula
by element’s name
add a Roman Numeral if it can form more than 1 type of ion
that is called the STOCK SYSTEM
anions
negative ion
written second in formula
by element’s root name + -ide ending

5. Binary Ionic Compounds
compounds made of two different ions
Crossing Over
write two ion types with correct charges
make the anion’s charge, the cation’s subscript
make the cation’s charge, the anion’s subscript
simplify the ratio if possible
combine the names of the two ions

6. Practice Naming Al and O Mg and Br Cu and Br Al3+ O2- Al2O3
aluminum oxide
Mg and Br
Mg2+ Br1-
MgBr2
magnesium bromide
Cu and Br
Cu2+ Br1-
CuBr2
copper (II) bromide OR
Cu1+ Br1-
CuBr
copper (I) bromide

7. Practice Writing Formulas
iron (III) sulfide
Fe3+ S2-
Fe2S3
cadmium oxide
Cd2+ O2-
Cd2O2
CdO
potassium nitride
K1+ N3-
K3N
tin (IV) sulfide
Sn4+ S2-
Sn2S4
SnS2

8. Cmpds with Polyatomic Ions
the cation or anion could be a group of covalently bonded atoms instead of one atom
most polyatomic ions are oxyanions:
polyatomic ions containing oxygen
more than one polyatomic anion can exist for one element
sulfate ion: SO42- sulfite ion: SO32-

9. Practice Naming KNO3 NH4Br Cu(OH)2 CaSO4 potassium nitrate
from K1+ and NO31-
Cu(OH)2
copper (II) hydroxide
from Cu2+ and OH1-
NH4Br
ammonium bromide
from NH41+ and Br1-
CaSO4
calcium sulfate
from Ca2+ and SO42-

10. Practice Writing Formulas
sodium permanganate
Na1+ MnO41-
NaMnO4
iron (II) chlorite
Fe2+ ClO21-
Fe(ClO2)2
ammonium acetate
NH41+ CH3COO1-
NH4CH3COO
calcium carbonate
Ca2+ CO32-
CaCO3