#### Transcript Notes - Nomenclature File

```Class Notes: Naming and Writing Formulas
• 2 ways to determine the charge on
an ion:
1. By group in the P.T.: Group number tells
number of valence electrons, which
determines whether atom needs to gain
or lose electrons
2. By Name: used for most transition metals and
two representative metals by including a Roman
numeral in the name
Ex. Roman Numerals
– Iron(II) = Fe2+
– Iron(III) = Fe3+
– Copper(I) = Cu+
– Copper(II) = Cu2+
• Memorize exceptions: Ag+, Zn2+, Cd2+; Sn, Pb
• Polyatomic Ions = a group of atoms which
behave as a unit and carry a charge
• Be able to recognize polyatomics (on back
• -all anions except ammonium NH4+
• -all but 3 end in –ite or –ate(exceptions:
CN- cyanide, OH- hydroxide, ammonium)
Binary Ionic Compound = made of 2 parts
-1 cation and 1 anion = metal & nonmetal
*Writing the formula from the name
(+) must equal (-)
-write the formulas for both ions
-show the charges
-put the cation (positive ion) first
*The criss-cross method
Switch the charges for the ions and
write them as subscripts
Calcium bromide = CaBr2
Iron (III) oxide = Fe2O3
*subscripts must be in the lowest whole
number ratio
Calcium sulfide = CaS
*writing the name from the formula
-metal + nonmetal-ide
CaCl2 = Calcium chloride
K2S =
Potassium sulfide
Ionic Compounds with Polyatomics
Ionic Compounds with Polyatomics
-contains atoms of 3 or more different elements
-contain 1 or more polyatomic ions
(on the back of your periodic table)
*Writing the formulas from the name
-same as for a binary ionic
-treat the polyatomic as ONE ion
-ate or –ite ending means polyatomic ion
-write the formulas for the two ions showing
charges
- criss-cross charges
Aluminum nitrate = Al(NO3)3
Nickel (I) sulfite = Ni2SO3
Iron (III) phosphate = FePO4
Calcium hydroxide = Ca(OH)2
Writing the name from the formula
-name the cation first
-Write the name of the polyatomic
Mg3(PO4)2 = Magnesium Phosphate
NaCN = Sodium Cyanide
NH4NO2 = Ammonium Nitrite
NH4Cl = Ammonium Chloride
Binary Molecular Compounds
Binary Molecular Compounds
-contain 2 nonmetals
-composed of molecules
therefore ionic charges not involved
-elements can combine in more than one
way
CO
CO2
Therefore, we need a way to distinguish
between them
Prefixes = use to show numbers of each
atom in the molecule
(never used with metal/ionic compounds)
-all binary compounds end in –ide
*memorize: mono = 1
di
=2
tri
=3
tetra = 4
penta = 5
hexa = 6
hepta = 7
octa = 8
nona = 9
deca = 10
Naming
-be on the lookout for 2 nonmetals
-subscripts are the prefixes
-don’t put mono- in front of 1st element
-drop first vowel if two vowels together,
except (i)
CBr4 = Carbon tetrabromide
BCl3 = Boron trichloride
P2O5 = Diphosphorus pentoxide
Formulas
– prefixes are the subscripts
Carbon dioxide =
Carbon monoxide =
CO2
CO
Dinitrogen pentasulfide = N2S5
Triphosphorous hexabromide = P3Br6
```