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Unit 5“Chemical Names
and Formulas”
H2O
Section 9.1Naming Ions
Atoms and Ions• Atoms are
electrically neutral.–Same number of p+ and e-
• Ions - atoms with a charge (+ or -)
• Made by gaining or losing electrons.– Only electrons can move
An Anion is…• A negative ion = gained
electrons.• Nonmetals 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 = losing
electrons.• Metals lose electrons
K1+ Has lost one electron (no name change for positive ions)
Ca2+ Has lost two electrons
Predicting Ionic ChargesGroup 1A:Lose 1 electron to form 1+ ions
H1+ Li1+ Na1+ K1+ Rb1+
Predicting Ionic ChargesGroup 2A:Loses 2 electrons to form 2+ ions
Be2+ Mg2+ Ca2+ Sr2+ Ba2+
Predicting Ionic ChargesGroup 3A: Loses 3 electrons to form 3+ ions
B3+ Al3+ Ga3+
Predicting Ionic Charges
Group 4A: Do they lose 4 electrons or gain 4 electrons?
Neither! Group 4A elements rarely form ions (they tend to share)
Predicting Ionic ChargesGroup 5A: Gains 3 electrons to form 3- ions
N3-
P3-
As3-
Nitride
Phosphide
Arsenide
Predicting Ionic ChargesGroup 6A: Gains 2 electrons to form 2- ions
O2-
S2-
Se2-
Oxide
Sulfide
Selenide
Predicting Ionic ChargesGroup 7A: Gains 1 electron to form 1- ions
F1-
Cl1-
Br1-Fluoride
Chloride
Bromide
I1-Iodide
Predicting Ionic ChargesGroup 8A: Stable noble gases do not form ions!
Predicting Ionic ChargesGroup B elements: Many transition elements have more than one possible charge.Iron (II) = Fe2+
Iron (III) = Fe3+
Use of Roman numerals to show charges
Naming Cations
• Stock system – use roman numerals in parenthesis to indicate the charge value
Naming cations• If the charge is always the same
(like in the Group A metals) just write the name of the metal.– Calcium =
• Transition metals can have more than one type of charge.– Indicate charge as roman numeral in
parenthesis after the name of the metal (Table 9.2, p.255)
– Iron (IV) =
Predicting Ionic Charges Some post-transition elements also have more than one possible charge.
Tin (II) = Sn2+ Lead (II) = Pb2+
Tin (IV) = Sn4+ Lead (IV) = Pb 4+
Predicting Ionic ChargesGroup B elements: Some transition elements have only one possible oxidation state, such as these three:
Zinc = Zn2+Silver = Ag1+ Cadmium = Cd2+
**Do not use roman numerals for these
Practice by naming these:• Na+ • Ca2+ • Al3+ • Fe3+ • Fe2+ • Pb2+ • Li+
Sodium
Calcium
Aluminum
Iron (III)
Iron (II)
Lead (II)
Lithium
Write symbols for these:
• Potassium ion• Magnesium ion • Copper (II) ion• Chromium (IV) ion• Barium ion• Mercury (II) ion
𝐾 +¿ ¿
𝑀𝑔+2
𝐶𝑢+2
𝐶𝑟 +4
𝐵𝑎+2
𝐻𝑔+ 2
Naming Anions
• Anions are always the same charge
• Change the ending to –ide
• F1- a Fluorine atom will become a Fluoride ion.
Practice by naming these:
• Cl- • N3- • Br- • O2-
• Ga3+
h𝐶 𝑙𝑜𝑟𝑖𝑑𝑒𝑁𝑖𝑡𝑟𝑖𝑑𝑒𝐵𝑟𝑜𝑚𝑖𝑑𝑒𝑂𝑥𝑖𝑑𝑒𝐺𝑎𝑙𝑙𝑖𝑢𝑚
Write symbols for these:
•Sulfide ion• Iodide ion•Phosphide ion•Strontium ion
𝑆−2
𝐼−
𝑃−3
𝑆𝑟 +2
Polyatomic ions are…• Groups of atoms that stay together,
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
(One of the few positive polyatomic ions)
H + Polyatomic ion =….
•If the polyatomic ion begins with H, then put “hydrogen” in front of the polyatomic ion: H1+ + CO3
2- → H2CO3
hydrogen + carbonate → hydrogen carbonate ion
• H2SO3
• H3PO4
• HNO3
Hydrogen Sulfite
Hydrogen Phosphate
Hydrogen Nitrate
Helpful Hints on Oxy-Anions
1. _________: smaller # of oxygen2. _________: larger # of oxygen
Ex.
NO3- ____________________________
NO2- ____________________________
SO42- ____________________________
SO32- ____________________________
-ite-ate
Nitrate
Nitrite
Sulfate
Sulfite
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
Section 9.2 Naming and Writing
Formulas for Ionic Compounds
Writing Ionic Compound FormulasExample: Iron (III) chloride
Fe3+Cl-
Not balanced!
3
Now balanced.
= FeCl3
1. Write the cation and anion with CHARGES!
2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.
Writing Ionic Compound Formulas
Example: Aluminum sulfideAl3+ S2-
Not balanced!
2 3
Now balanced.
= Al2S3
1. Write the cation and anion with CHARGES!
2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.
Writing Ionic Compound Formulas
Example: Zinc hydroxide
Zn2+ OH-
Not balanced!
( ) 2
Now balanced.
= Zn(OH)2
1. Write the cation and anion with CHARGES!
2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.
Writing Ionic Compound Formulas
Example: Magnesium carbonate (note the 2 word name)
1. Write the formulas for the cation and anion, including CHARGES!
Mg2+CO32-
2. Check to see if charges are balanced.
They are balanced!
= MgCO3
Writing Ionic Compound Formulas
Example: Barium nitrate (note the 2 word name)1. Write the cation and anion with CHARGES! Ba2+ NO3
-
2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.
Not balanced!
( ) 2
Now balanced.
= Ba(NO3)2
Writing Ionic Compound FormulasExample: Ammonium sulfate
NH4+ SO4
2-
Not balanced!
( )2
Now balanced.
= (NH4)2SO4
1. Write the cation and anion with CHARGES!
2. Balance charges using the criss-cross method with subscripts, if necessary. Use parentheses if you need more than one of a polyatomic ion to balance subscripts.
Writing Ionic Compound Formulas
Example: Aluminum phosphate
1. Write the formulas for the cation and anion, including CHARGES!
Al3+ PO43-
2. Check to see if charges are balanced.
They ARE balanced!= AlPO4
Naming Ionic Compounds• 1. 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 Compounds
• If the metal can have more than one charge (Group B), use a Roman numeral in their name:
PbCl2 use the anion to find the
charge on the cation (chloride is always 1-)
(Metals with multiple oxidation states)
Pb2+ is the lead (II) cation
PbCl2 = lead (II) chloride
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
𝐹𝑒3(𝑃𝑂 ¿¿ 4)¿2SnF𝐾 2𝑆(𝑁𝐻 4)𝐶𝑟𝑂42
Magnesium Sulfate
Ferrous (III) Chloride
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
Section 9.3Naming and Writing
Formulas for Molecular
Compounds
Molecular compounds are…• Made of only nonmetals
• Smallest part is a molecule• Can’t use charges to figure
out how many of each atom (there are no charges present / they share electrons)
Molecular compounds are easier!• Ionic compounds use charges
to determine how many of each.• Figure out charges and 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-
• 9 = nona-• 10 = deca-
Prefixes• To write the name, include:
• 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 -ide
Practice by naming these:
• N2O
• NO2
• Cl2O7
• CBr4
• CO2
• BaCl2 Ionic! So… Barium Chloride
= dinitrogen monoxide
(also called 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)
𝑃2𝑂5
𝐼 4𝑂9
𝑆𝐹 6
𝑁𝑂3
𝐶𝐻4
P𝐴𝑙𝐶𝑙3
Section 9.4Naming and Writing Formulas for Acids
and Bases
Acids are…• Compounds that give off
hydrogen ions (H+) when dissolved in water (the Arrhenius definition)
• Formula starts with H.• Always be some Hydrogen
next to an anion.• Anion determines the name.
Rules for Naming acids: Name it as a normal compound first
• If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid
• In other words, if it’s just Hydrogen and one other nonmetal
• HCl = • H2S =
hydrochloric acidhydrosulfuric acid
Naming Acids• If the anion has oxygen in it, then it ends
in -ate or -ite2) Change -ate to -ic acid (use no prefix)
• Example: HNO3 Hydrogen + nitrate =
3) Change -ite to -ous acid (use no prefix)• Example: HNO2 Hydrogen + nitrite
=
Nitric acid
Nitrous acid
Naming Acids
Normal ending
____-ide
____-ate
____-ite
Acid name is…
hydro-___-ic acid
_____-ic acid
_____-ous acid
Practice by naming these:
• HF• H3P
• H2SO4
• H2SO3 • HCN• H3PO4
Hydrofluoric Acid
Hydrophosphic AcidSulfuric Acid
Sulfurous Acid
Hydrocyanic Acid
Phosphoric Acid
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 hydro?• Anion is
monatomic, ends in –ide
• No hydro?
1) -ate anion comes from –ic ending
2) -ite anion comes from –ous ending
Write formulas for these:
• hydroiodic acid• chloric acid• carbonic acid• phosphorous acid• hydrobromic acid
𝐻𝐼❑
𝐻𝐶𝑙𝑂3
𝐻2𝐶𝑂3
𝐻3 𝑃𝑂3
𝐻𝐵𝑟❑
Names and Formulas for Bases
• Base - an ionic compound that produces hydroxide ions (OH1-) when dissolved in water (the Arrhenius definition)
• Named the same way as other ionic compounds:–Name of cation (metal) followed by
name of anion (which will be hydroxide).
Names and Formulas for Bases
• NaOH =• Ca(OH)2 =
• To write the formula:
1) Write symbol for metal cation
2) Followed by hydroxide ion (OH1-)
3) Use criss-cross method to balance the charges.
sodium hydroxide
calcium hydroxide
Practice by writing the formula for the following:
• Magnesium hydroxide• Iron (III) hydroxide• Zinc hydroxide
𝑀𝑔(𝑂𝐻 )2
𝐹𝑒(𝑂𝐻 )3
𝑍𝑛 (𝑂𝐻 )2
Section 9.5The Laws Governing
Formulas and Names
Some Laws:
Law of Definite Proportions- in a sample of a chemical compound, the masses of the elements are always in the same proportions.
In every molecule of H2O (water), the mass ratio of H:O is 1:8
Some Laws:Law of Multiple Proportions- Whenever two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.
H2O (water) and H2O2 (hydrogen peroxide)
2:1 2:2
2g:16g 2g:32g
• https://www.youtube.com/watch?v=0OOcpiTiXzM
• Law of Definite Proportions - Law of Multiple Proportions
• by Brightstorm
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 ionic compounds, the net charge is
zero (criss-cross method)2. Put -ide at the end of monatomic
nonmetals3. An -ite or -ate ending means there is a
polyatomic ion that has oxygen
4. Prefixes generally mean molecular; they show the number of each atom
Helpful to remember...5. A Roman numeral after the name
of a cation is the charge of the cation
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 2 (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• B• Cu (I)
Anions (Top)• SO3
• ClO2
• SO4
• O• F• C8H4O4
• OH