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CH 5 NOTES
Section 5.1
Objectives:
#1 ~ Apply ionic charge to writing formulas for ionic
compounds.
#2 ~ Apply formulas to name ionic compounds.
#3 ~ Interpret the information in a chemical formula.
Section Focus Transparency
What are the names of some useful ionic compounds?
Binary Ionic Compounds
Contain only two elements, but may contain more than one
ion of each element!
**Subscripts
NaCl
AlCl3
Naming:
1. Write the name of the + ion (usually a metal)
2. Write the name of the – ion (usually a nonmetal),
but change the ending on the ending to “-ide”
Formula Unit: the simplest ratio of ions in an ionic
compound
Predicting Charge: You can already do this!
Oxidation Number: the charge on the ion…See Table 5.1
**When a compound forms, these charges MUST
add up to zero! The compound will be NEUTRAL, right?
Ex. Mg 2+ and O 2- combine to form MgO
Practice Problems: p. 156
Polyatomic Ions : an ion with 2 or more different
elements covalently bonded, but with a charge;
See Table 5.2 (p. 157)
**The charge is associated with the whole ion…the
individual atoms do not have charge!
**Subscripts
Practice Problems: p. 160
Writing Formulas with Polyatomic Ions
Examples:
Compounds of Transition Elements: Groups 3-12
When naming, you must use Roman Numerals to identify
the oxidation number of the metal!
Ex. FeCl3 is iron (III) chloride
FeCl2 is iron (II) chloride
*** Elements in Group 3-12 (like iron) can have multiple
oxidation numbers ***
As a result, the transition elements can form a wide
variety of compounds…with very different properties
Zinc, Cadmium and Silver are exceptions!
Zinc and Cadmium are always 2+ and Silver is always 1+
Naming and Writing Formulas for Compounds with
Transition Elements
Practice Problems: p. 163
DEMO: Iron (II and III) Ammonium Sulfate
DEMO: Variable Oxidation States
HYDRATES
DEMO: Copper (II) sulfate pentahydrate
CuSO4 ∙ 5H2O
Hydrates : Ionic compounds that have water molecules
chemically bonded to them.
Ex. CuSO4 ∙ 5H2O; Copper (II) sulfate pentahydrate
Anhydrous : all the water is removed (with heat) from a
compound. (Blue to white in our demo)
Hygroscopic : can become a hydrate by absorbing the
water vapor in the air.
Deliquescent : can take up enough water from the air
that the compounds dissolves completely and forms a
liquid.
DEMO: A Deliquescent Compound, Sodium Hydroxide,
NaOH
Naming Hydrates: See Table 5.5 for Prefixes
Practice Problems, p. 813 #s 18 and 19
Section 5.2
Objectives:
#1 ~ Compare the properties of molecular and ionic
substances.
#2 ~ Distinguish among allotropes of an element.
#3 ~ Apply formulas to name molecular compounds.
Section Focus Transparency
What are some names of useful molecular substances?
Molecular Substances: have atoms held together by
covalent bonds
General Properties: lower melting points; less soluble in
water; not electrolytic; not as hard as ionic compounds
Distillation : process which uses the differences between
ionic and covalent compounds to separate them from one
another…remember the apparatus? (p. 171)
Molecular Elements: when atoms of the same elements
bond together to form a molecule…NOT compounds
Diatomic Elements: What are the 7?
How do they bond?
Allotropes: molecules made up of a single type of element
that differ in their molecular structure.
O2 (oxygen) and O3(ozone); Graphite, Coal, Diamonds (all
carbon)
Hole in the Ozone
Organic v. Inorganic Compounds:
Naming Molecular Binary Inorganic Compounds
1. Write the name of the first nonmetal if it occurs only
once
a. If the first nonmetal occurs more than once, you must
use the appropriate prefix
b. Ex. H2O ~ dihydrogen
2. Write the name of second nonmetal and no matter how
many times it occurs in the formula, use the appropriate
prefix AND change the ending of the nonmetal name to “ide”
a. Ex. H2O ~ dihydrogen monoxide
Table 5.5 Prefixes (You must know mono- through deca-)
Practice problems p. 179
Common Names Acids & Bases: You must know these by
heart:
HCl hydrochloric acid
H2SO4 sulfuric acid
HNO3 nitric acid
NH3 ammonia
Hydrocarbons: organic compounds made up of only
hydrogen and carbon
Ex. Methane (natural gas) is CH4
Table 5.8, p. 183 has the rest