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