Transcript CHAPTER 5.1 - pdecandia.com

CHAPTER 5.1
IONIC COMPOUNDS
IONIC COMPOUNDS
•
•
•
•
•
•
Charged ions with neutral cpd.
Water soluble
Metal with non metal
Brittle
Electric conductor
Tightly bound repeating patterns in crystals
• Cation: + charged ion
• Anion: - charged ion
Types of Ionic Compounds
I. Binary Ionic Compounds
•
only contains 2 elements
(can have more than one ion of each element)
- Bi – Latin for “2”
Ex: NaCl sodium chloride
- charges cancel each other
- compound is neutral
- do not write charges of ions in
formula
- 1:1 ratio of each element
Binary Ionic Compounds
ex: CaFl2 calcium flouride
(1:2 ratio)
AlCl3 aluminum chloride
(1:3 ratio)
K2S
potassium sulfide
(2:1 ratio)
Naming Binary Ionic Compounds
Rules
1. Write name of metal
( + cation)
2. Write name of non metal
(- anion)
3. Change non metal name to end in “ide”
(number of each element does not change name)
Name the following binary compounds:
Mg2O3
magnesium oxide
KCl
potassium chloride
Na2S
sodium sulfide
LiI
lithium iodide
TiBr
titanium bromide
Writing Formulas
Rules
1. If more than one ion of an element is present, the subscript tells
how many
2. Write subscript below and to the right of element
(sub-below)
3. Write the formula unit (simplest ratio of elements)
Ex: FORMULA UNIT
CaF2
NaCl
Ga2S3
REPEATING PATTERN
Ca2F4
Ca3F6
Na2Cl2
Na6Cl6
Ga4S6
Ga8S12
Write the formula units for the following:
Rb2F2
RbF
Mg3Cl9
MgCl3
Al6O18
AlO3
C12H24O12
CH2O
H4S2O8
H2SO4
Writing Binary Ionic Formulas
Rules
1. Write the symbol for the metal then the non-metal
2. Determine the oxidation number of each element
(use periodic table)
oxidation number: charge on ion (superscript)
- tells number of electrons atom gains or loses
Oxidation Numbers
Metals:
- always have + charge (lose negative electrons)
- charge equals group # on periodic tbl.
(remove 1 in front of group 13)
Oxidation Numbers
Non metals:
- always have – charge (gain negative electrons)
- charge equals 8 minus group #
(remove 1 in front of groups 15, 16, 17, 18)
3. Rewrite formula so compound is neutral
(positive and negative charges must be equal)
2+
–
ex: Mg Br
Are the charges equal?
In order for the compound to be neutral we must
have equal positive and negative charges.
CRISS-CROSS RULE
1. take number of metal’s superscript
(number above element)
2. move this number to bottom right of non-metal symbol
(now a subscript, loses charge)
3. do the same for the non-metal
Criss Cross Rule
Ex: Mg Br
Mg 2+ Br -
Mg1 Br2
Final Formula (do not write charges on subscripts)
Mg Br2
charges are equal, compound is neutral
Mg has 2+ charges x one atom = 2+ charges
Br has 1- charge x two atoms = 2- charges
II.
Polyatomic Compounds
compound that contains more than two elements
•
Polyatomic Ion: Ion that has two or more different
elements in a grouped unit which carries a charge
a. whole ion is charged, not last element listed
b. treated same as single element’s (monoatomic) ion
ex: ammonium cyanide
+
NH4 CN
polyatomic polyatomic
ion
ion
c.
can contain:
1.
one (+) metal bonded to (–) polyatomic ion
+
Na OH
-
metal nonmetal
2.
(+) polyatomic ion bonded to one (-) non metal ion
+ -
NH4 I
polyatomic nonmetal
ion
3. (+) polyatomic ion bonded to a (-) polyatomic ion
+
-
NH4 NO3
polyatomic
polyatomic
Naming Polyatomic Compounds
Rules
1. name + ion first, followed by name of – polyatomic ion
2. do not change ending of – polyatomic ion
ex:
CaCO3
calcium carbonate
Name the following polyatomic
compounds:
(use reference sheet)
LiNO2
lithium nitrate
NaCN
sodium cyanide
MgSO4
magnesium sulfate
AlSO3
aluminum sulfite
CaPO4
calcium phosphate
KNO3
potassium nitrate
NaOH
sodium hydroxide
MgCr2O7
magnesium dichromate
* H3OCl
hydronium chloride
* NH4I
ammonium iodide
* Remember to change non
metal’s name to “ide”
Writing Polyatomic Formulas
Rules
1. Use criss-cross method
ammonium nitride
NH4+ N3-
2. Put parenthesis around
polyatomic ion
3. Criss-cross superscript to
bottom right of parenthesis
around polyatomic ion
(NH4) 3 N1
hydronium phosphide
H3O + P2(H3O)2P
Practice Problems
III. Transition Element Compounds
(groups 3-12)
a. form + ions like metals
b. can have more than one type of + ion
(have more than 1 oxidation number)
c. named by using name of element followed by
oxidation number as Roman numeral in parenthesis
ex: Cu(I)Cl
Cu(II)Cl
copper I chloride
copper II chloride
IV.
Hydrates
ionic compound that contains H2O molecules weakly bound in its
crystals
- when hydrates lose their water, the end compound
has different properties than the original hydrate
ex: popcorn kernel
yellow, hard
cobalt chloride
(anhydrous)
cement gel
popped corn
white, soft
cobalt chloride
(hydrate)
cement hardened
Hygroscopic substances:
Ionic compounds that easily become hydrates (absorb H2O)
The thorny devil features hygroscopic grooves between the spines
of their skin to capture water in their desert habitat.
Deliquescent substances:
Substance that absorbs so much water it becomes liquid
salts
Dessicants:
Absorb water vapor and keeps surrounding substance dry
silica gel packs inside electronics
Anhydrous compound:
Hydrate with all water removed
anhydrous sodium sulfate
Naming Hydrates
Rules
1. Write the name of the compound
2. Write the prefix of the number of water molecules
3. Add the word “hydrate” to the prefix
ex: Ba(NO3)2 . 4 H2O
barium nitrite tetrahydrate
Prefixes for Naming Compounds
Number
Prefix
1
Mono-
2
Di-
3
Tri-
4
Tetra-
5
Penta-
6
Hexa-
7
Hepta-
8
Octa-
9
Nona-
10
Deca-
Name the following hydrates:
CaSO4 . 3 H2O
NaSO4 . 4 H2O
. 6 H2O
NiNo3
.
7 H2O
NaOH .
9 H2O
FeO2
LiPO4 . 10 H2O
. 5 H2O
MgCr2O7 . H2O
AlSO3
KCl
BaOH
.
2 H2O
.
8 H2O
Writing Hydrate Formulas
Rules
1. Write the formula for the compound (must be neutralized)
2. Place a dot after formula
3. Write the number of water molecules
ex: copper sulfate dihydrate
CuSO4 . 2 H2O
sodium carbonate pentahydrate
Na2CO3 . 5 H2O
Write the formulas for the following hydrates:
Beryllium sulfite pentahydrate
Cesium chloride trihydrate
Copper (I) phosphate decahydrate
Barium oxide octahydrate
Calcium hydroxide dihydrate
Scandium (II) bromide trihydrate
Sodium carbonate nonahydrate
Potassium sulfide heptahydrate
Radium flouride hexahydrate
Ammonium cyanide monohydrate
Study for the test !