Chemical Formulas and Chemical Compounds
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Transcript Chemical Formulas and Chemical Compounds
Chemical Formulas and
Chemical Compounds
Chapter 7
Chemical Formulas
Aluminum Sulfate formula unit
Al2(SO4)3
Carbon Tetrachloride molecule
CCl4
Monatomic Ions
Def: ions formed from a single atom
Naming ions
Cation – use element name
Li+1 – Lithium ion Al+3 – Aluminum ion
Anion – change ending of element to –ide
N-3 – Nitride ion O-2 – Oxide ion
Monatomic Ions
d – block elements and others with
multiple ions
Use Roman numeral in name
Fe+3 Iron(III) ion
Fe+2 Iron(II) ion
Metals always have positive charge
Polyatomic Ions
Polyatomic Ions
NO3- Nitrate
NO2- Nitrite
The –ate means 1 more oxygen
SO4-2 Sulfate
SO3-2 Sulfite
Polyatomic Ions
ClO4- Perchlorate
ClO3- Chlorate
ClO2- Chlorite
ClO - Hypochlorite
Binary Ionic Compounds
Def: composed of 2 elements
Total (+) charge must = total (-) charge
Write the formula:
Mg and Cl
Mg+2 Cl-1
MgCl2
K and N
Al and O
Compounds with Polyatomic
Ions
Iron(II) and Nitrite
Silver and Chromate
Calcium and Hydroxide
Naming Ionic Compounds
Name the cation first, then the anion
NaOH
RbCl
Ag2SO3
Fe3N2
CuMnO4
Writing Formulas
Potassium sulfide
Copper(II) sulfate
Sodium carbonate
Calcium chloride
Aluminum hypochlorite
Naming Binary Covalent
Compounds
CO, CO2
We use PREFIXES in the name!!
Only COVALENT compounds use
PREFIXES
Prefixes
Mono-
One
Hexa-
Six
Di-
Two
Hepta-
Seven
Tri-
Three
Octa-
Eight
Tetra-
Four
Nona-
Nine
Penta-
Five
Deca-
Ten
Covalent Naming Rules
1. Use prefixes to show how many of each
element
•
Single atom in first element, mono is not
used
2. The second element name ends in –ide
3. Drop vowel at end of prefix if element
begins with vowel (except: di and tri)
Examples
N2O4
PCl5
S3Br6
Nitrogen Dioxide
Boron Trifluoride
Diphosphorus Pentoxide
Naming Acids
Begin with Hydrogen (H)
2 types of acids:
1. Oxyacids:
hydrogen and polyatomic ion
2. Binary Acids:
w/o oxygen
hydrogen and halogen **CN-
Naming Oxyacids
Replace ending of anion name
Anion Suffix
Acid Suffix
- ite
- ous
- ate
- ic
Naming Oxyacids
H2SO4 anion SO4-2 Sulfuric Acid
H2SO3
HClO4
HNO3
Naming Oxyacids
Acetic Acid
Dichromic Acid
Nitrous Acid
Naming Binary Acids
Use prefix hydroUse suffix –ic
Followed by acid
Naming Binary Acids
HCl
HF
HI
HBr
HCN
Formula Mass
Mass of H2O?
Formula Mass: mass of molecule,
formula unit, or ion is sum of masses of
all atoms represented (amu)
Ca(NO3)2
Molar Mass
Def: mass of 1 mole of compound –
use molar masses of elements (g/mol)
(NH4)2CrO4
Molar Mass in Conversions
Remember flow chart??
Grams Moles Particles
What is mass (g) of 3.04 mol of
ammonia vapor, NH3?
How many molecules are in 4.15 x 10-5g
C6H12O6?
More Conversions
How many H atoms are in 7.1 moles of
C6H12O6?
How many formula units are in 4.5 kg
Ca(OH)2?
What is the mass of H2SO4, if you have
1.53 x 1023 hydrogen ions in your
compound?
Percent Composition
A basket of fruit = 120 g
3 apples = 50 g
2 oranges = 35 g
2 bananas = 20 g
Basket = 15 g
What percentage of the basket’s mass
is from the apples?
Percent Composition
What is the percent composition by
mass of each element in (NH4)2O?
What percentage by mass of
Al2(SO4)36H2O is water?
Empirical Formula
Def: formula showing smallest wholenumber mole ratio
Ex: B2H6 Molecular Formula
BH3 Empirical Formula
Finding Empirical Formula
Determine the empirical formula of the
compound with 17.15% C, 1.44% H,
and 81.41% F.
CHF3
Finding Empirical Formula
Find empirical formula of 26.56% K,
35.41% Cr, and rest O.
K2Cr2O7
Finding Molecular Formula
x(empirical formula) = molecular formula
x(Emp.Form Mass) = Molec.Form Mass
x = Molecular Mass
Empirical Mass
Finding Molecular Formula
Determine molecular formula of
compound with empirical formula CH
and formula mass of 78.110 amu.
Finding Molecular Formula
Sample has formula mass of 34.00 amu
has 0.44g H and 6.92g O. Find its
molecular formula.