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Chapter 5
Naming Compounds
Writing Formulas
Naming Binary Ionic Compounds Binary Compounds - 2 elements. Ionic - a cation and an anion. To write the names just name the two
ions. Easy with Representative elements. Group A NaCl = Na+ Cl- = sodium chloride
MgBr2 = Mg+2 Br- = magnesium bromide
Naming Binary Ionic Compounds The problem comes with the transition
metals. Need to figure out their charges. The compound must be neutral. same number of + and – charges. Use the anion to determine the charge
on the positive ion.
Naming Binary Ionic Compounds Write the name of CuO Need the charge of Cu O is -2 copper must be +2 Copper (II) chloride Name CoCl3
Cl is -1 and there are three of them = -3 Co must be +3 Cobalt (III) chloride
Naming Binary Ionic Compounds Write the name of Cu2S. Since S is -2, the Cu2 must be +2, so
each one is +1. copper (I) sulfide Fe2O3 Each O is -2 3 x -2 = -6 2 Fe must = +6, so each is +3. iron (III) oxide
Naming Binary Ionic Compounds Write the names of the following KCl Na3N
CrN
Sc3P2
PbO
PbO2
Na2Se
Ternary Ionic Compounds Will have polyatomic ions At least three elements Just write the name of the element using the
front of the periodic table and the polyatomic ion using the chart on the back of the table.
Examples of naming ternary ionic compounds:
NaNO3 = sodium nitrate (NH4)2O = ammonium oxide
Ternary Ionic Compoundsname these:
LiCN Fe(OH)3
(NH4)2CO3
NiPO4
CaSO4
CuSO3
Writing Formulas The charges have to add up to zero. Get charges for the 2 parts. Cations from location on p. table. Anions from p. table or polyatomic. Balance the charges by putting in
subscripts (small #’s on bottom right). Put polyatomic ions in parenthesis
before you give them subscripts.
Writing Formulas Write the formula for calcium chloride. Calcium is Ca+2 Chloride is Cl-1 Ca+2 Cl-1 would have a +1 charge. Need another Cl-1 Ca+2 Cl2
-1
CaCl2
Write the formulas for these Lithium sulfide tin (II) oxide tin (IV) oxide Magnesium fluoride Copper (II) sulfate Iron (III) phosphide gallium nitrate Iron (III) sulfide
Write the formulas for these Ammonium chloride ammonium sulfide barium nitrate
Things to look for If cations have (roman numeral), the
number is their charge. If anions end in -ide they are probably
off the periodic table (Monoatomic) Exceptions (Hydroxide (OH); Cyanide (CN)
are polyatomic. If anion ends in -ate or -ite it is
polyatomic.
Molecular Compounds
Writing names and Formulas
Molecular compounds made of just nonmetals smallest piece is a molecule can’t be held together because of
opposite charges can’t use charges to figure out how
many of each atom
Easier Ionic compounds use charges to
determine how many of each.
– Have to figure out charges.
– Have to figure out numbers. Molecular compounds name tells you
the kind of atoms. Uses prefixes to tell you the number
Prefixes 1 mono- 2 di- 3 tri- 4 tetra- 5 penta-
6 hexa-•7 hepta-•8 octa- •9 nona-•10 deca-
Prefixes To write the name write two words
Prefix name Prefix name -ide
Prefixes To write the name write two words
One exception is we don’t write mono- if there is only one of the first element.
Prefix name Prefix name -ide
Prefixes To write the name write two words
One exception is we don’t write mono- if there is only one of the first element.
No double vowels when writing names (oa oo)
Prefix name Prefix name -ide
Name These N2O
NO2
Cl2O7
CBr4
BaCl2
Ex. CO carbon monoxide
CO2 carbon dioxide
P2O5 diphosphorus pentoxide
Write formulas for these diphosphorus pentoxide tetraiodide nonoxide sulfur hexaflouride nitrogen trioxide Carbon tetrahydride phosphorus trifluoride aluminum chloride
Acids
Writing names and Formulas
Acids Compounds that give off hydrogen ions
when dissolved in water. Must have H in them. will always be some H next to an anion. The anion determines the name.
Naming acids If the anion attached to hydrogen is
ends in -ide, put the prefix hydro- and change -ide to -ic acid
HCl - hydrogen ion and chloride ion hydrochloric acid H2S hydrogen ion and sulfide ion hydrosulfuric acid
Naming Acids If the anion has oxygen in it it ends in -ate or -ite change the suffix -ate to -ic acid HNO3 Hydrogen and nitrate ions
Nitric acid change the suffix -ite to -ous acid HNO2 Hydrogen and nitrite ions
Nitrous acid
Name these HF H3P
H2SO4
H2SO3
HCN H2CrO4
Writing Acid Formulas/Naming Hydrogen will always be first name will tell you the anion make the charges cancel out Starts with hydro- if no oxygen in the acid, -ide
ending becomes –icEx. HCl = hydochloric acid
no hydro, -ate ending from polyatomic ion becomes -ic, H2SO4 = sulfuric acid
-ite ending becomes –ous, H2SO3 = sulfurous acid
Write formulas for these hydroiodic acid acetic acid carbonic acid phosphorous acid hydrobromic acid