unit 4 “chemical names and formulas” chemistry troy high school mr. blake/gower h2oh2o
TRANSCRIPT
Unit 4“Chemical Names
and Formulas”
ChemistryTroy High SchoolMr. Blake/Gower
H2O
Atoms and Ions• Atoms are electrically neutral.
– Because there is the same number of protons (+) and electrons (-).
• Ions are atoms, or groups of atoms, with a charge (positive or negative)– They have different numbers of
protons and electrons.• Only electrons can move, and
ions are made by gaining or losing electrons.
An Anion is…• A negative ion.• Has gained electrons.• Nonmetals can gain electrons.• Charge is written as a superscript on
the right.
F1- Has gained one electron (-ide is new ending = fluoride)
O2- Gained two electrons (oxide)
A Cation is…• A positive ion.• Formed by losing electrons.• More protons than electrons.• Metals can lose electrons
K1+ Has lost one electron (no name change for positive ions)
Ca2+ Has lost two electrons
Predicting Ionic ChargesGroup 1AGroup 1A::Lose 1 electron to form Lose 1 electron to form 1+1+ ions ions
HH1+1+ LiLi1+1+ NaNa1+1+ KK1+1+ RbRb1+1+
Predicting Ionic ChargesGroup 2AGroup 2A::Loses 2 electrons to form Loses 2 electrons to form 2+2+ ions ions
BeBe2+2+ MgMg2+2+ CaCa2+2+ SrSr2+2+ BaBa2+2+
Predicting Ionic ChargesGroup 3AGroup 3A:: Loses 3 Loses 3 electrons to form electrons to form 3+3+ ions ions
BB3+3+ AlAl3+3+ GaGa3+3+
Predicting Ionic ChargesGroup 4AGroup 4A:: Do they Do they loselose 4 electrons 4 electrons or or gaingain 4 4 electrons?electrons?
Neither!Neither! Group 4A Group 4A elements rarely elements rarely form ions form ions (they (they tend to share)tend to share)
Predicting Ionic ChargesGroup 5AGroup 5A:: Gains 3 Gains 3 electrons to form electrons to form 3-3- ions ions
NN3-3-
PP3-3-
AsAs3-3-
Nitride
Phosphide
Arsenide
Predicting Ionic ChargesGroup 6AGroup 6A:: Gains 2 Gains 2 electrons to form electrons to form 2-2- ions ions
OO2-2-
SS2-2-
SeSe2-2-
Oxide
Sulfide
Selenide
Predicting Ionic ChargesGroup 7AGroup 7A:: Gains Gains 1 electron to 1 electron to form form 1-1- ions ions
FF1-1-
ClCl1-1-
BrBr1-1-Fluoride
Chloride
Bromide
II1-1-Iodide
Predicting Ionic ChargesGroup 8AGroup 8A:: Stable Stable noble gases noble gases do do notnot form ions! form ions!
Predicting Ionic ChargesGroup B Group B elementselements::
Many Many transitiontransition elements elements have have more than onemore than one possible oxidation possible oxidation state.state. Iron (II) = Fe2+
Iron (III) = Fe3+
Note the use of Roman numerals to show charges
Naming Cations• Two methods can clarify when
more than one charge is possible:1)Stock system – uses roman
numerals in parenthesis to indicate the numerical value
2)Classical method – uses root word with suffixes (-ous, -ic)• Does not give true value
Naming cations• We will use the Stock system.• Cation - if the charge is always the
same (like in the Group A metals) just write the name of the metal.
• Transition metals can have more than one type of charge.– Indicate their charge as a roman
numeral in parenthesis after the name of the metal (Table 9.2, p.255)
Predicting Ionic Charges Some of the Some of the post-transitionpost-transition elements elements also also have have more than onemore than one possible oxidation possible oxidation state.state.Tin (II) = Sn2+ Lead (II) = Pb2+
Tin (IV) = Sn4+ Lead (IV) = Pb 4+
Predicting Ionic ChargesGroup B Group B elementselements:: Some Some transitiontransition elements elements have have only oneonly one possible oxidation state, possible oxidation state, such as these four:such as these four:
Zinc = Zn2+Silver = Ag1+ Cadmium = Cd2+
Nickel = Ni2+
Exceptions:•Some of the transition metals
have only one ionic charge:
–Do not need to use roman numerals for these:
–Silver is always 1+ (Ag1+)–Cadmium and Zinc are always 2+ (Cd2+ and Zn2+)
Fig. 2.11
Practice by naming these:•Na+ •Ca2+ •Al3+ •Fe3+ •Fe2+ •Pb2+ •Li+
Sodium Ion
Lead (II) Ion
Aluminum IonIron (III) Ion
Iron (II) Ion
Calcium Ion
Lithium Ion
Write symbols for these:
•Potassium ion•Magnesium ion •Copper (II) ion•Chromium (II) ion•Barium ion•Mercury (II) ion
K+
Mg2
+Cu2+
Cr2+
Ba2+
Hg2+
Naming Anions
•Anions are always the same charge
•Change the monatomic element ending to – ide
•F1- a Fluorine atom will become a Fluoride ion.
Practice by naming these:
•Cl- •N3- •Br- •O2-
•Ga3+
ChlorideNitrideBromide
Oxide
Gallium Ion
Write symbols for these:
•Sulfide ion•Iodide ion•Phosphide ion•Strontium ion
S2-
I-
P3-
Sr2+
Polyatomic ions are…• Groups of atoms that stay together
and have an overall charge, and one name.
• Usually end in –ate or -ite
• Acetate: C2H3O2-
• Nitrate: NO3-
• Nitrite: NO2-
• Permanganate: MnO4-
• Hydroxide: OH- and Cyanide: CN-?
• Sulfate: SO42-
• Sulfite: SO32-
• Carbonate: CO32-
• Chromate: CrO42-
• Dichromate: Cr2O72-
• Phosphate: PO43-
• Phosphite: PO33-
• Ammonium: NH41+
Know Table 9.3 on page 257 and your Ion Sheet!!!!!!
If the polyatomic ion begins with H, then combine the word hydrogen with the other polyatomic ion present: H1+ + CO3
2- → HCO31-
hydrogen + carbonate → hydrogen carbonate ion
(One of the few positive polyatomic ions)
Helpful Hints on Oxy-Anions
1. _________: smaller # of oxygen2. _________: larger # of oxygen
Ex.
NO3- ____________________________
NO2- ____________________________
SO42- ____________________________
SO32- ____________________________
-ite-ate
Nitrate
Nitrite
Sulfate
Sulfite
hypo -ite ClO- ______________________-ite ClO2
- ______________________ClO3
- ______________________
per -ate ClO4- ________________
“_________” = sulfur replacing an oxygen.
Ex. OCN- ____________________________
SCN- ____________________________
SO42- ____________________________
S2O32- ____________________________
HypochloriteChloriteChlorate
Perchlorate-thio
Cyanate
Thiocyanate
Sulfate
Thiosulfate
-ate
A Guide to Determine Whether the –ate Formula is –XO3 or –XO4:
B C N
Cl
Br
I
Si P S
As Se
1
2
3
4
5
6
1 2 13 14 15 16 17 18
Transition Metals
A Guide to Determine What the Charge of the Oxy-Anion is:
B C N
Cl
Br
I
Si P S
As Se
1
2
3
4
5
6
1 2 13 14 15 16 17 18
Transition Metals
-1-2-3
-1
-1
-1
-2-3- 4
-2-3
Writing Ionic Compound Formulas
Example: Barium nitrate (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES! BaBa2+2+ NONO33
--
2. Check to see if charges are balanced.
3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance subscripts.
Not balanced!
(( )) 22Now balanced.
= Ba(NO3)2
Writing Ionic Compound Formulas
Example: Ammonium sulfate (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!
NHNH44++ SOSO44
2-2-
2. Check to see if charges are balanced.
3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.
Not balanced!
( )( )22
Now balanced.
= (NH4)2SO4
Writing Ionic Compound Formulas
Example: Iron (III) chloride (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!
FeFe3+3+ClCl--
2. Check to see if charges are balanced.
3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.
Not balanced!
33Now balanced.
= FeCl3
Writing Ionic Compound Formulas
Example: Aluminum sulfide (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!
AlAl3+3+ SS2-2-
2. Check to see if charges are balanced.
3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.
Not balanced!
22 33Now balanced.
= Al2S3
Writing Ionic Compound Formulas
Example: Magnesium carbonate (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!
MgMg2+2+ COCO332-2-
2. Check to see if charges are balanced.
They are balanced!
= MgCO3
Writing Ionic Compound Formulas
Example: Zinc hydroxide (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES!
ZnZn2+2+ OHOH--
2. Check to see if charges are balanced.
3. Balance charges , if necessary, using subscripts. Use parentheses if you need more than one of a polyatomic ion. Use the criss-cross method to balance the subscripts.
Not balanced!
( )( )22
Now balanced.
= Zn(OH)2
Writing Ionic Compound Formulas
Example: Aluminum phosphate (note the 2 word name)1. Write the formulas for the cation and anion, including CHARGES! AlAl3+3+ POPO44
3-3-
2. Check to see if charges are balanced. They ARE
balanced!= AlPO4
Naming Ionic CompoundsNaming Ionic Compounds• 1. Name the cation first, then anion
• 2. Monatomic cation = name of the element
• Ca2+ = calcium ion
• 3. Monatomic anion = root + -ide
• Cl- = chloride
• CaCl2 = calcium chloride
Naming Ionic CompoundsNaming Ionic Compounds
• some metals can form more than one charge (usually the transition metals)
• use a Roman numeral in their name:
PbCl2 – use the anion to find the charge
on the cation (chloride is always 1-)
Pb2+ is the lead (II) cation
PbCl2 = lead (II) chloride
(Metals with multiple oxidation states)
Things to look for:
1) If cations have ( ), the number in parenthesis is their charge.
2) If anions end in -ide they are probably off the periodic table (Monoatomic)
3) If anion ends in -ate or –ite, then it is polyatomic
Practice by writing the formula or name as required…
•Iron (II) Phosphate•Stannous Fluoride•Potassium Sulfide•Ammonium Chromate
•MgSO4
•FeCl3
Nomenclature of Hydrates
A. Hydrate: Ionic compound with ______________ molecules stuck in the ___________ lattice.
The water is included in the ____________ and formula.
Ex. ZnSO4 7 H20: __________________________
CaCO3 3 H2O: __________________________
Cu2C2O4 2H2O: _________________________
Calcium chloride pentahydrate:______________
watercrystal
name
Zinc sulfate
Calcium carbonate
Copper (I) oxalate
CaCl2
heptahydrate
dihydrate
trihydrate
5H20
Molecular compounds are…•made of just nonmetals
•smallest piece is a molecule•can’t be held together by
opposite charge attraction•can’t use charges to figure
out how many of each atom (there are no charges present)
Molecular compounds are easier!• Ionic compounds use charges to
determine how many of each.–You have to figure out charges.–May need to criss-cross numbers.
• Molecular compounds: the name tells you the number of atoms.– Uses prefixes to tell you the exact
number of each element present!
Prefixes (Table 9.4, p.269)• 1 = mono-• 2 = di-• 3 = tri-• 4 = tetra-• 5 = penta-• 6 = hexa-• 7 = hepta-• 8 = octa-
Prefixes
• 9 = nona-• 10 = deca-• To write the name, write two words:
• One exception is we don’t write mono if there is only one of the first element.
• Normally, we do not have double vowels when writing names (oa oo)
Prefix name
Prefix name
-ide
Practice by naming these:
•N2O
•NO2
•Cl2O7
•CBr4
•CO2
•BaCl2 (This one will not use prefixes, since it is an ionic compound!)
= dinitrogen monoxide
(also called nitrous oxide or laughing gas)
= nitrogen dioxide= dichlorine heptoxide= carbon tetrabromide= carbon dioxide
Write formulas for these:•diphosphorus pentoxide•tetraiodine nonoxide•sulfur hexafluoride•nitrogen trioxide•carbon tetrahydride•phosphorus trifluoride•aluminum chloride(Ionic compound)
Acids are…•Compounds that give off
hydrogen ions (H1+) when dissolved in water (the Arrhenius definition)
•Will start the formula with H.•There will always be some
Hydrogen next to an anion.•The anion determines the
name.
Rules for Naming acids: Name it as a normal compound first1) 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 Acids• If the anion has oxygen in it, then it
ends in -ate or -ite2) change the suffix -ate to -ic acid (use
no prefix)• Example: HNO3 Hydrogen and
nitrate ions = Nitric acid3) change the suffix -ite to -ous acid
(use no prefix)• Example: HNO2 Hydrogen and
nitrite ions = Nitrous acid
Naming Acids
Normal ending
____-ide
____-ate
____-ite
Acid name is…
hydro-___-ic acid
_____-ic acid
_____-ous acid
2 additional rules (not mentioned in the book)
4) If the acid has 1 more oxygen than the –ic acid, add the prefix per-
a. HClO3 (Hydrogen Chlorate) is chloric acid
b. HClO4 would be perchloric acid
5) If there is 1 less oxygen than the -ous acid, add the prefix hypo-
• HClO2 (Hydrogen Chlorite) is chlorous acid, then HClO would be hypochlorous acid
Practice by naming these:
•HF
•H3P
•H2SO4
•H2SO3
•HCN
•H2CrO4
Writing Acid Formulas – in reverse!• Hydrogen will be listed first• The name will tell you the anion• Be sure the charges cancel out.• Starts with prefix hydro?- there is
no oxygen, -ide ending for anion• no prefix hydro?
1) -ate anion comes from –ic ending2) -ite anion comes from –ous ending
Write formulas for these:
•hydroiodic acid•acetic acid•carbonic acid•phosphorous acid•hydrobromic acid
Summary of Naming and Formula Writing
•For naming, follow the flowchart- Figure 9.20, page 277
•For writing formulas, follow the flowchart from Figure 9.22, page 278
Helpful to remember...1. In an ionic compound, the net ionic
charge is zero (criss-cross method)2. An -ide ending generally indicates a
binary compound3. An -ite or -ate ending means there
is a polyatomic ion that has oxygen4. Prefixes generally mean molecular;
they show the number of each atom
Compounds
Ionic Covalent
(Metal / Non-metal)
Binary Ternary
Acids
Contain H+
Binary Ternary
w/ oxygen
Hydrates
• 2 elements
• -ide
• Roman numeral
(if needed)
• ie. Calcium chloride
CaCl2
• 3 or more elements
• Anion is named
• Roman numerals
(if needed)
• ie. Calcium carbonate
CaCO3
• Non-metal / Non-metal
• Uses prefixes, -ide
• I2O7 Diiodine heptoxide
• No oxygen
• Hydro__ic acid
• ie, Hydrochloric acid
HCl
• -ate—ic
acid
• H2CO3
Carbonic
acid
• -ite---ous
acid
• H2SO3
Sulfurous
acid
• w/ H2O
• Uses prefixes
• ie. Calcium chloride
dihydrate
CaCl2 2H2O•
Ion Bingo Set 1 (Choose 5 each for your blank sheet and mix them
up)Cations (Left side)
• Mg• Pb (II)• Li• Ca• K• Al
• NH4
Anions (Top)
• CO3
• NO2
• PO4
• S• Br
• C2O4
• Cl
Ion Bingo Set 2 (Choose 5 each for your blank sheet and mix them
up)Cations (Left side)
• Fe (III)• Zn• Cs• Sr• Ni• Ba• Cu (I)
Anions (Top)
• SO3
• ClO2
• SO4
• O• F
• C8H4O4
• OH
Ion Quiz #1Version A
1. Sulfate2. Magnesium ion3. Charges of Lead4. Carbonate5. Phosphide6. Charges of Mercury7. Charge of silver8. cyanide9. Nitrate10.Aluminum ion
Version B1. Rubidium ion2. Hydroxide3. Charges of Chromium4. Sulfide5. sulfite6. Charges of Tin7. Nitrate8. Bromide9. Charge of Zinc10.Chlorate
Ion Quiz #2Ver. A
1. AsO33-
2. Bromate3. OH-
4. Phosphite5. Hg2
2+
6. Charge(s) of Mn7. Ammonium8. SO3
2-
9. IO4-
10.OCN-
Ver. B1. IO2
-
2. NO2-
3. O22-
4. Cyanide5. Hg2+
6. Charge(s) of Pb7. SO4
2-
8. BO33-
9. Carbonate10.ClO-
Ion Quiz #3
1) AsO33-
2) Charge of Cadmium
3) NH4+
4) Charge(s) of Silver
5) S2O32-
6) Dichromate
7) Hypochlorite
8) MnO4-
9) Sulfate
10) Oxalate
1) C2H3O2-
2) Charge(s) Manganese
3) OH-
4) Charge(s) of Copper
5) SO32-
6) Chromate
7) Perchlorate
8) CO32-
9) Monohydrogen Phosphate
10)Periodate
Ver. A Ver. B
Ion Quiz # 1 Key (Per. 0/1)
1. SO42-
2. Mg2+
3. +2/+4
4. CO32-
5. P3-
6. +2/+3
7. +1
8. CN-
9. NO3-
10.Al3+
1. Rb+
2. OH-
3. +1/+2
4. S2-
5. PO43-
6. +2/+4
7. NO3-
8. Br-
9. +2
10.SO32-
Ver. A Ver. B
Ion Quiz # 1 Key (Per. 2)
1. SO42-
2. Mg2+
3. +2/+4
4. CO32-
5. P3-
6. +1/+2
7. +1
8. CN-
9. NO3-
10.Al3+
1. Rb+
2. OH-
3. +2/+3
4. S2-
5. PO43-
6. +2/+4
7. NO3-
8. Br-
9. Zn2+
10.ClO3-
Ver. A Ver. B
Ion Quiz # 1 Key (Per. 3/4)
1. SO42-
2. Mg2+
3. +2/+4
4. CO32-
5. P3-
6. +1/+2
7. +1
8. CN-
9. NO3-
10.Al3+
1. Rb+
2. OH-
3. +2/+3
4. S2-
5. SO32-
6. +2/+4
7. NO3-
8. Br-
9. Zn2+ (2+)
10.ClO3-
Ver. A Ver. B
Ion Quiz # 2 Key
1. Arsenite
2. BrO3-
3. Hydroxide
4. PO33-
5. Mercury (I)
6. +2/+3
7. NH4+
8. Sulfite
9. Periodate
10.Cyanate
1. Iodite
2. Nitrite
3. Peroxide
4. CN-
5. Mercury (II)
6. +2/+4
7. Sulfate
8. Borate
9. CO32-
10.Hypochlorite
Ver. A Ver. B
Ion Quiz #3 Key
1) Arsenite
2) +2
3) Ammonium Ion
4) +1
5) Thiosulfate
6) Cr2O72-
7) ClO-
8) Permanganate
9) SO42-
10) C2O42-
1) Acetate
2) +2/+3
3) Hydroxide
4) +1/+2
5) Sulfite
6) CrO42-
7) ClO4-
8) Carbonate
9) HPO42-
10) IO4-
Ver. A Ver. B