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Naming and Formula Writing
+ Chemical Formulas
Shows the kind and number of atoms in the smallest piece of a substance
Use subscripts to show the number of atoms per element
Molecular formula- number and kinds of atoms in a covalent molecule
CO2
C6H12O6
Smallest ratio of atoms in an Ionic Compound is the Formula Unit
NaCl
BaCl2
+ Laws of Chemical Formulae
Law of Definite Proportions- In a sample of a chemical compound, the masses of the elements are always in the same proportions
H2O (water) and H2O2 (Hydrogen peroxide)
Law of Multiple Proportions- atoms can combine in multiple ratios to form different compounds with different properties (Dalton)
H2O is different than H2O2
CO is a poisonous gas, CO2 is not
+ Categories of Chemical Naming
Ionic Compounds
Combinations of metal and nonmetal ions
Binary- 2 ions
Ternary-3 ions, and polyatomic ions
Covalent Molecules:
Combinations of nonmetals
Acids
Simple binary acids
Oxyacids
Organic Chemistry
+ Remember Ionic Compounds
Ionic Compounds- from joining metal cations and
nonmetal anions
Electrically neutral
Cation and anion surround each other in a crystal
lattice structure
Smallest ratio of atoms is the formula unit
Melt at high temperatures
+ Naming Ionic Compounds
First, name the metal, or cation: Positive ions are formed by losing e- There is no name change for the positive ions Name is the same as the metal atom
K+ potassium Ca2+ calcium
+ Naming Ionic Compounds
Transition metals can have more than one type of
charge
In the stock system, indicate the charge with roman
numerals in parenthesis
Cu+ Copper (I)
Cu +2 Copper (II)
Fe+2 Iron (II)
Fe+3 Iron (III)
Sn+2 Tin (II)
Sn+4 Tin (IV)
+ Other Transition Metals with Multiple Charges
+ Naming Ionic Compounds
Transition Metals and the Classical System:
The suffix –ous is used to indicate the lower valence,
or lower positive charge
The suffix –ic is used to name the metal with the
higher valence electrons, or higher positive charge
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+ Transition Metal Exceptions
Some of the transition metals have only one
ionic charge
Do NOT use roman numerals for these:
Aluminum is always +3
Zinc is always +2
Silver is always +1
+ Naming Ionic compounds
Second, name the nonmetal, or anion:
Negative ion formed by a nonmetal atom gaining
electrons
For these anions, drop the ending of the atom’s name,
and add –ide
F- Fluoride
O2- Oxide
Cl- Chloride
N3- Nitride
+ What are ternary ionic compounds?
Ternary Ionic Compounds have three different
elements
These compounds have POLYATOMIC IONS
Polyatomic ions are groups of elements, with a
single charge, that behave as one element in an
ionic compound
+ Converting formula to name: binary edition
KCl
BaS
Al2O3
Na3N
Fe2O3
Sc3P2
+ What are ternary ionic compounds?
Ternary Ionic Compounds have three
different elements
These compounds have POLYATOMIC IONS
Polyatomic ions are groups of elements with a
single charge that behave as one element in
an ionic compound
+ Converting Formula to Name: Ternary edition
Na2CO3
FeSO3
CaSO4
NH4OH
K3PO4
LiCn
+ Names from Formulas
The Criss-Cross Method Returns
Write the formula for Aluminum Oxide
Al3+ + O2-
Al2 O3
Write the formula for Copper (II) Hydroxide
Cu2+ + OH-
Cu(OH)2
+ Converting Name to Formula
Tin (IV) Carbonate
Copper (I) cyanide
Aluminum Fluoride
Sodium Hydroxide
Lithium Nitrite
Calcium Phosphate
+ Covalent
In ionic compounds, the number of atoms is easily determined from the name and expected charge of the ions
Covalent molecules are held together by sharing of electrons, and not balanced ionic charge
Name has to include more information
+ Covalent Molecules
Made from only nonmetals
Can be from one element
O2, N2, H2, F2, Cl2, Br2, & I2
The molecule’s name is simply the name of the
element
Can be made of 2 or more nonmetals
CO2, N2O, H2O
The name has to detail exactly how many of each
element is present in the molecule
+ Covalent Molecules
Covalent compounds use
prefixes
Mono- 1
Di- 2
Tri- 3
Tetra- 4
Penta- 5
Hexa- 6
Hepta- 7
Octa- 8
Nona- 9
Deca- 10
• Otherwise, left right
nomenclature of ionic compounds
is used.
• Mono is left off for first atom;
• NO2 nitrogen dioxide
• No double vowels when writing
names (oa, oo)
• tetroxide
+ Covalent Molecules
CO
CO2
H2O
P2O3
CCl4
SF6
+ Names from Formulas
Diphosphorus pentoxide
Tetraiodine nonoxide
Silicon hexafluoride
Nitrogen trioxide
Carbon tetrahydride
Phosphorus trifluoride
+ Naming and writing Formulas for acids
What is an acid?
Compounds that give off H+ 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 simple binary acids
If the anion attached to hydrogen 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 Oxyacids
If the anion has oxygen in it, the polyatomic ion’s
name ends in –ate or –ite
Change the suffix –ate to –ic acid (no prefix)
HNO3 Hydrogen and nitrate ions
Nitric Acid
Change the suffix –ite to –ous acid
HNO2 Hydrogen and nitrite ions
Nitrous acid
+ Writing Acid Formulas
Hydrogen will always be first
Name will tell you the anion
Make the charges cancel
Starts with “Hydro” if no oxygen, -ide
No hydro? –ate comes from –ic, -ite comes from –ous
SO42- is sulfate: H2SO4 is Sulfuric Acid
SO32- is sulfite; H2SO3 is Sulfurous Acid
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