Unit 5 “Chemical Names and Formulas” H2OH2O. Section 9.1 Naming Ions

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