Molecules and Compounds: Nomenclature

2

Compounds vs. ElementsCompound 1: Table Salt

Properties: Soluble crystals, stable, edibleElements (Components)• Sodium – shiny, reactive, poisonous• Chlorine – pale yellow gas, reactive,

poisonous

Compound 2: Table sugarProperties: sweet, soluble crystalElements (Components) :• Carbon – pencil or diamonds• Hydrogen – flammable gas• Oxygen – a gas in air Sugar:

3

Law of Constant CompositionPure substances have constant composition

all samples of a pure substance contain the same elements in the same percentages (ratios): Water (H: 11%, O: 89%), Table salt (Na: 39%, Cl: 61%), Sugar

mixtures have variable composition: Air, Seawater, Concrete, Rocky road ice cream, Coke

4

Why do Compounds ShowConstant Composition

• the smallest piece of a compound is called a molecule: Water molecule, Sugar molecule

• every molecule of a compound has the same number and type of atoms.

Water molecule: 2 Hydrogen atom + 1 Oxygen atom;

Sugar molecule: 12 Carbon atom + 22 Hydrogen atom + 11 Oxygen atom

every sample of the compound will have the same ratio of the elements

5

Chemical FormulaChemical formula: describe the compound by

describing the number and type of each atom in the simplest unit of the compoundmolecules or ions (Table salt: Cl+, Na-)

• Element represented by its letter symbol: H instead of hydrogen; Na instead of Sodium

• #Atoms of each element: the right of the element as a subscript, H2O (unless if there is only one atom, the 1 subscript is not written)

• Polyatomic groups (multiple atoms in group, example: CO3) are placed in parentheses if more than one

6

From Composition to Chemical Formula

water = H2O two atoms of

hydrogen and 1 atom of oxygen

table sugar = C12H22O11 12 atoms

of C, 22 atoms of H and 11 atoms O

7

Classifying Pure Substances

Element• Atomic: consists of single atoms

(Metals, Noble gases)• Molecular: consists of multi-atom

molecules (O2, N2, Cl2, etc)

Compound• Molecular: consists of molecules

made of only nonmetals (CO2, H2O)• Ionic: consists of cations (Na+) and

anions (Cl-)

8

Elements and Compounds

9

Classify each of the following:Element atomic/molecular

Compound molecular/ionic

• aluminum, Al

• aluminum chloride, AlCl3

• chlorine, Cl2

• acetone, C3H6O

• carbon monoxide, CO

• cobalt, Co

• aluminum, Al = atomic element

• aluminum chloride, AlCl3 = ionic compound

• chlorine, Cl2 = molecular element

• acetone, C3H6O = molecular compound

• carbon monoxide, CO = molecular compound

• cobalt, Co = atomic element

10

Molecular ElementsCertain elements occur as 2 atom molecules• Rule of 7’s

there are 7 common diatomic elements find the element with atomic number 7, Nmake a figure 7 by going over to Group 7A, then downdon’t forget to include H2

H2

Cl2

Br2

I2

7VIIA

N2 O2 F2

Molecular Elements

IBrCl

N O FH

= Metal

= Metalloid

= Nonmetal

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Molecular Compounds

• two or more nonmetals• smallest unit is a

molecule

• Common examples: H2O

• CO2 (as in soda and dry ice)

• NH3 (as in Windex),

• Table sugar C11H22O11

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Ionic Compounds

Ions: Metals (Cation Mx+) and Nonmetals (Anion Ny-)

• No individual molecules!!• have a 3-dimensional array

of cations and anions made of formula units: NaCl, MgO

• Na+ Cl- Na+ Cl- Na+ Cl- • Cl- Na+ Cl- Na+ Cl- Na+

• Na+ Cl- Na+ Cl- Na+ Cl-

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Binary Molecular Compounds:Two Nonmetals (such as CO2)

1. Name first element in formula first use the full name of the element

2. Name the second element in the formula with an -ide as if it were an anion, however, remember these

compounds do not contain ions!

3. Use a prefix in front of each name to indicate the number of atoms

a) Never use the prefix mono- on the first element

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Subscript - Prefixes

• 1 = mono-; not used on first

nonmetal

• 2 = di-

• 3 = tri-

• 4 = tetra-

• 5 = penta-• 6 = hexa-• 7 = hepta-• 8 = octa-• drop last “a” if

name begins with vowel

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Exceptions when Naming Molecular Compounds

of course, water

Other common exceptions:• NH3: ammonia (as in Windex)• H2S: hydrogen sulfide• HCl: hydrogen chloride (same for HX, where X =

halogen)• CH4: methane (as in natural gas)

• H2O2: hydrogen peroxide

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Example – Naming Binary Molecular

BF3

1. Is it one of the common exceptions?H2O, NH3, CH4, C12H22O11 = No!

2. Identify Major ClassB = is a nonmetal because it is on the right side of the PT

F = is a nonmetal because it is on the right side of the PT

Molecular

3. Identify the Subclass2 elements Binary Molecular

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Example – Naming Binary Molecular BF3

4. Name the first element boron5. Name the second element with an –ide

fluorine fluoride6. Add a prefix to each name to indicate the subscript

monoboron, trifluoride7. Write the first element with prefix, then the second

element with prefix Drop prefix mono from first element

boron trifluoride

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Practice:

Naming Molecular Compounds

• CO

• ClO3

• SO2

• P2O5

• N2O4

• IF7

• SF6

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• CO carbon monoxide

• ClO3 chlorine trioxide

• SO2 sulfur dioxide

• P2O5 diphosphorus pentoxide

• N2O4 dinitrogen tetroxide

• IF7 iodine heptoxide

• SF6 sulfur hexafluoride

Key to Naming Molecular Compounds

• CO

• ClO3

• SO2

• P2O5

• N2O4

• IF7

• SF6

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Ionic Compounds

• Made of Cation (+) and Anion (-)• Name: Cation Anion

example: NaCl Sodium ChlorideCation:

Type I metalType II metal Polyatomic ion: ammonium NH4

+

Anion:Nonmetal: Chloride Cl-, Oxide O2-

Polyatomic ion: SO42- , OH- , NO3

-

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Metal Cations: Type IType I (Groups IA, IIA, AZA)

only have one possible chargeGroups IA, IIA, Ag+, Zn2+, Al3+

Charge by position on the Periodic TableIA = +1, IIA = +2, Ag+ (IB), Zn2+(IIB) Al3+(IIIA)

How do you know a metal cation is Type II?

its not Type I !!!

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Metal Cations: Type IIType II: Metal ions that are

other than Type I

Common Examples: Fe2+/3+, Cu+/2+, Cr3+/6+, Mn2+/4+, Mn2+/4+, Pb2+/4+, Sn2+/4+, etc ) have more than one possible

chargedetermine charge by charge on

anion

How do you know a metal cation is Type II?

its not Type I !!!

Metal Cations: Type I vs. Type II

AgZn

Al

= Type II Metal

= Type I Metal

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Monatomic Nonmetal Anion (An-)

• How much is the charge? the position on the Periodic Table

• Name of the anion: change ending on the element name to –ide

4A = -4 5A = -3 6A = -2 7A = -1

C4- = carbide N3- = nitride O2- = oxide F- = fluoride

Si4- = silicide P3- = phosphide S2- = sulfide Cl- = chloride

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Net charge of Ionic Compound = 0

• Net charge = Positive charge from cation(s) + Negative charge from Anion(s) = 0

• Example: Compound Al2(SO4)3, the Net

charge = 2 x (+3) + 3 x (-2) = +6 - 6 = 0

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Name of Ionic Compounds

• Name: Cation Anion: Sodium ChlorideCation:

Type I metal = metal name : Na+ => Sodium, Mg2+ => Magnesium

Type II metal = metal name(charge): Fe3+ Iron(III), Cu2+ Copper(II)

Polyatomic ion = name of polyatomic ion, NH4+ => Ammonium

Anion:Nonmetal = stem of nonmetal name + ide, Chloride, OxidePolyatomic ion = name of polyatomic ion, SO4

2- => Sulfate, OH- => Hydroxide, NO3

- => Nitrate

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Type I Binary Ionic CompoundsBinary: only two kinds of ions in one UNIT

Example: MgO, CaCl2

• Metal listed first in formula & name

1. Metal Cation Nonmetal Anion2. Cation name <= Metal name: Magnesium,

Calcium3. Nonmetal anion <= Nonmetal name ends with

–ide: Oxide, Chloride

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Example – Naming Binary Ionic, Type I Metal CsF

1. Is it one of the common exceptions?

H2O, NH3, CH4, C12H22O11 No!

2. Identify Major ClassCs = is a metal because it is on the left side of the PT

F = is a nonmetal because it is on the right side of the PT

Ionic

3. Identify the Subclass2 elements, Binary Ionic

4. Is the metal Type I or Type IICs is in Group IA, Type I

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Example – Naming Binary Ionic, Type I Metal

CsF5. Identify cation and anion

Cs = Cs+ because it is Group 1F = F- because it is Group 7

6. Name the cationCs+ = cesium

7. Name the anionF- = fluoride

8. Full name: Cation name first, Anion name lastcesium fluoride

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Type II Binary Ionic Compounds

Metal listed first in formula & name

1. Metal cation Nonmetal anion2. metal cation Metal(Roman Numeral): to indicate

its charge. Iron(II), Copper(I) determine charge from anion charge Common Type II cations in Table 5.5

3. Nonmetal anion Nonmetal name ended with –ide: Chloride, Oxide

Example: Iron(II) chloride, Copper(I) oxide

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How to find the charge on Type II metal ions?

• Example: Name Compound Fe2(SO4)3

Since the sum of all charges equals zero, the charge on iron ions are unknown and sulfate each has –2 charge, then we have

2 x Fe + 3 x (-2) = 0

Fe = +3, each iron ion has a charge of +3

Name: iron(III) sulfate

Key: knowing the charge on ANIONs!

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Example – Naming Binary Ionic, Type II Metal

CuCl1. Is it one of the common exceptions?

H2O, NH3, CH4, C12H22O11 = No!2. Identify Major Class

Cu = is a metal because it is on the left side of the PTCl = is a nonmetal because it is on the right side of the PT

Ionic

3. Identify the Subclass2 elements, Binary Ionic

4. Is the metal Type I or Type IICu is not in Group IA, IIA, or (Al, Ga, In) Type II

34

Example – Naming Binary Ionic, Type II Metal CuCl

5. Identify cation and anionCl = Cl- because it is Group 7

Cu = Cu+ to balance the charge

6. Name the cationCu+ = copper(I)

7. Name the anionCl- = chloride

8. Write the cation name first, then the anion namecopper(I) chloride

35

Practice: Naming Ionic compounds

• HgF2

• CuI2

• CaCl2

• Fe2O3

• SnCl4

• Mg3N2

• Ag2S

36

Naming Ionic compounds Hints: find type II ion charge from anion

• HgF2 : Two F- = -2

• CuI2 : Two I- = -2

• CaCl2 : both fixed charges

• Fe2O3 : Three O2- = -6

• SnBr4 : Four Br- = -4

• Mg3N2 : both fixed charges

• Ag2S : both fixed charges

• HgF2 : Two F- = -2 Hg = +2

• CuI2 : Two I- = -2 Cu = +2

• CaCl2 : both fixed charges

• Fe2O3 : Three O2- = -6 Fe = +3

• SnBr4 : Four Br- = -4 Sn = +4

• Mg3N2 : both fixed charges

• Ag2S : both fixed charges

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Answer key: names of ionic compounds

• HgF2 = Mercury(II) fluoride

• CuI2 = copper(II) iodide

• CaCl2 = calcium chloride

• Fe2O3 = Iron(III) oxide

• SnBr4 = tin(IV) bromide

• Mg3N2 = magnesium nitride

• Ag2S = silver sulfide

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Polyatomic Ions

Mg(NO3)2

compound calledmagnesium nitrate

symbol of the polyatomic ion called nitrate

symbol of the polyatomic ion called sulfate

CaSO4

compound calledcalcium sulfate

implied “1” subscripton magnesium

implied “1” subscripton calcium

parentheses to group two NO3’s no parentheses for one SO4

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Polyatomic Ions:Nitrate NO3

-, Sulfate SO42-

Mg(NO3)2

compound calledmagnesium nitrate

CaSO4

compound calledcalcium sulfate

subscript indicatingtwo NO3 groups

no subscript indicatingone SO4 group

implied “1” subscripton nitrogen, total 2 N

implied “1” subscripton sulfur, total 1 S

stated “3” subscripton oxygen, total 6 O

stated “4” subscripton oxygen, total 4 O

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Polyatomic Anions: -ATE ions

CO32-

carbonate

NO3-

nitrate

SiO32-

silicate

PO43-

phosphate

SO42-

sulfate

ClO3-

chlorate

AsO43-

arsenate

SeO42-

selenate

BrO3-

bromate

IO3-

iodate

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Periodic Pattern of Polyatomic Ions-ate groups

BO33- NO3

-

SiO32-

PO43-

SO42-

ClO3-

AsO43-

SeO42-

BrO3-

TeO42-

IO3-

CO32-

IIIA IVA VA VIA VIIA

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Patterns for Polyatomic Ions

1. elements in the same Group form similar polyatomic ions

same number of O’s and same charge

ClO3- = chlorate (-1 charge)

BrO3- = bromate (-1 charge)

2. if the polyatomic ion starts with H, the name adds hydrogen- prefix before name and add 1 to the charge

CO32- = carbonate HCO3

-1 = hydrogen carbonate

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Patterns for Polyatomic Ions-ate ion

chlorate = ClO3-

• -ate ion + 1 O same charge, per- prefixperchlorate = ClO4

-

• -ate ion – 1 O same charge, -ite suffixchlorite = ClO2

-

• -ate ion – 2 O same charge, hypo- prefix, -ite suffixhypochlorite = ClO-

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Polyatomic Anions: -ite, hypo- -ite, (-ate), per- -ate

ClO-

hypochlorite

NO2-

nitrite

PO33-

phosphite

SO32-

sulfite

ClO2-

chlorite

NO3-

nitrate

PO43-

phosphate

SO42-

sulfate

ClO3-

chlorate

ClO4-

perchlorate

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-ATE/-ITE ions in Our Lives

ClO-

(bleach)

NO2-

(preserve meat)

PO33-

(plant medicine)

SO32-

(wine, oxygen buster)

ClO2-

(bleach, disinfect)

NO3-

(fertilizer, explosives)

PO43-

(bone/teeth, fertilizer, soda)

SO42-

(plaster, car battery, sea salt)

ClO3-

(older pyrotechnics)

ClO4-

(pyrotechnics, solid fuel rocket)

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Polyatomic Ions to RememberNameName FormulaFormula

acetate C2H3O2–

carbonate CO32–

hydrogen carbonate(aka Bicarbonate)

HCO3–

hydroxide OH–

nitrate NO3–

nitrite NO2–

permanganate MnO4–

chromate CrO42–

dichromate Cr2O72–

ammonium NH4+

NameName FormulaFormula

hypochlorite ClO–

chlorite ClO2–

chlorate ClO3–

perchlorate ClO4–

sulfate SO42–

Hydrogen sulfate(aka Bisulfate)

HSO4–

sulfite SO32–

Hydrogen sulfite(aka Bisulfite)

HSO3–

cyanide CN–

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Other Polyatomic Ions in Our Lives

C2H3O2– In vinegar as acetic acid

CO32– Soda drink

HCO3– Baking soda, baking power, acid spill

neutralizer

OH– In liquid plumber/Drano as NaOH

MnO4– Disinfectant, “aging” for movie making

CrO42– Chrome plating (faucet, etc.)

CN– Highly Poisonous; Plant seeds; blue pigment

NH4+ Fertilizer; metabolic waste from animals

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Other Polyatomic Ions in Our Lives

ClO-

(bleach)

NO2-

(preserve meat)

PO33-

(plant medicine)

SO32-

(wine, oxygen buster)

ClO2-

(bleach, disinfect)

NO3-

(fertilizer, explosives)

PO43-

(bone/teeth, fertilizer, soda)

SO42-

(plaster, car battery, sea salt)

ClO3-

(older pyrotechnics)

ClO4-

(pyrotechnics, solid fuel rocket)

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Compounds Containing Polyatomic Ions

• Type I metal + Polyatomic ion: NaNO3

• Type II metal(charge) + Polyatomic ion : CuSO4

• Polyatomic cation + Nonmetal ion (-ide): NH4Cl

• Polyatomic cation + Polyatomic ion: (NH4)2SO4

Important!:Important!: If, and only if, more than ONE polyatomic ions are present in a formula, use parenthesis and subscript to indicate the number of polyatomic ions

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Example – Naming Ionic with Polyatomic Ion

Na2SO41. Is it one of the common exceptions?

H2O, NH3, CH4, C12H22O11 = No!

2. Identify Major ClassNa = is a metal because it is on the left side of the PT

SO4 = is a polyatomic ion

Ionic

3. Identify the Subclasscompound has 3 elements Ionic with Polyatomic Ion

4. Is the metal Type I or Type IINa is in Group IA, Type I

51

5. Identify the ionsNa = Na+ because in Group 1

SO4 = SO42- a polyatomic ion

6. Name the cationNa+ = sodium (Type I)

7. Name the anionSO4

2- = sulfate

8. Write the name of the cation followed by the name of the anion

sodium sulfate

Example – Naming Ionic with Polyatomic Ion

Na2SO4

52

Example – Naming Ionic with Polyatomic Ion Fe(NO3)3

1. Is it one of the common exceptions?

H2O, NH3, CH4, C12H22O11 = No!

2. Identify Major ClassFe = is a metal because it is on the left side of the PT

NO3 = is a polyatomic ion because it is in ( )

Ionic

3. Identify the Subclassthere are 3 elements Ionic with Polyatomic Ion

4. Is the metal Type I or Type IIFe is not in Group IA, IIA, or (Al, Ga, In) Type II

53

Example – Naming Ionic with Polyatomic Ion Fe(NO3)3

5. Identify the ionsNO3 = NO3

- a polyatomic ion

Fe = Fe+3 to balance the charge of the 3 NO3-1

6. Name the cationFe+3 = iron(III) (Type II)

7. Name the anionNO3

- = nitrate

8. Write the name of the cation followed by the name of the anion

iron(III) nitrate

54

Practice: Naming Ionic compounds

• Hg2SO4

• CuClO3

• Zn(NO3)2

• FeCO3

• Sn(SO3)2

• CoPO4

• Al(ClO4)3

55

Hints: Naming Ionic compounds

• Hg2SO4 : charge of sulfate = -1

• CuClO3 : charge of chlorate = -1

• Zn(NO3)2 charge of nitrate = -1

• FeCO3 : charge of carbonate = -2

• Sn(SO3)2: charge of sulfite = -1

• CoPO4 : charge of phosphate = -3

• Al(ClO4)3 : charge of perchlorate = -1

56

Keys: Naming Ionic compounds

• Hg2SO4 : mercury(I) sulfate

• CuClO3 : copper(I) chlorate

• Zn(NO3)2 zinc nitrate

• FeCO3 : iron(II) carbonate

• Sn(SO3)2: tin(IV) sulfite

• CoPO4 : cobalt(III) phophate

• Al(ClO4)3 : aluminum perchlorate

57

Acids• Contain H+ cation and

anion• Hydrogen (H) as first

element in formula

• Binary acids (HnX) have H+ cation and nonmetal anion

• Oxyacids (HnXOm) have H+ cation and polyatomic anion

58

Naming AcidsAll names have acid at end• Binary Acids (HnX) = hydro prefix + stem of the

name of the nonmetal + ic suffixExample: HCl (Hydrochloric acid)

• Oxyacids (HnXOm : H2CO3 , H2SO4) if polyatomic ion ends in –ate = name of polyatomic ion

with –ic suffix :

H2SO4 (Sulfuric acid); H2CO3 (Carbonic acid);

HNO3 (Nitric acid); H3PO4 (Phosphoric acid)

if polyatomic ion ends in –ite = name of polyatomic ion with –ous suffix

59

Naming Binary Acids – HF

1. First of all, it is binary acid HX

2. Identify the anionF F-, fluoride because Group 7A

2. Name the anion with an –ic suffixF- = fluoride fluoric

3. Add a hydro- prefix to the anion namehydrofluoric

4. Add the word acid to the endhydrofluoric acid

60

Naming Oxyacids: H2SO4

1. Identify the anionSO4 = SO4

2- = sulfate

2. If the anion has –ate suffix, change it to –ic. If the anion has –ite suffix, change it to -ous

SO42- = sulfate sulfuric

3. Write the name of the anion followed by the word acidsulfuric acid

(kind of an exception, to make it sound nicer!)

61

Practice: Naming Acidsfirst: what is the anion?

• HNO3

• HClO3

• HBr

• H2CO3

• H2SO3

• H3PO4

• HClO4

Practice: Naming Acids

• HNO3 nitrate

• HClO3 chlorate

• HBr bromide

• H2CO3 carbonate

• H2SO3 sulfite

• H3PO4 phosphate

• HClO4 perchlorate

62

Practice: Naming Acids

• HNO3 nitrate nitric acid

• HClO3 chlorate chloric acid

• HBr bromide hydrobromic acid

• H2CO3 carbonate carbonic acid

• H2SO3 sulfite sulfurous acid

• H3PO4 phosphate phosphoric acid

• HClO4 perchlorate perchloric acid

63

Formula-to-Name Flow Chart

64

Review: Naming Compounds

• CuSO3

• AgClO

• N2O5

• H2S

• FeI2

• Sn(NO3)4

• Ba3(PO4)2

• (NH4)2S

1. Common exceptions? H2O, NH3, CH4, C12H22O11

2. Identify as Molecular or Ionic?

3. Identify • Binary molecular

• Type I or II metal ion

65

Review: Naming Compounds

• CuSO3 copper(II) sulfite• AgClO silver hypochlorite• N2O5 dinitrogen pentoxide• H2S hydrosulfuric acid• FeI2 iron(II) iodide• Sn(NO3)4 tin(IV) nitrate• Ba3(PO4)2 barium phosphate • (NH4)2S ammonium sulfide

66

Write Chemical Formula using the charge of known ions

• Example: Compound between Ca2+ and PO4

3- , the number of ions of each needs to

be 3 and 2, so that the combined charge

= 3 x (+2) + 2 x (-3) = 0

Therefore the formula for the compound is Ca3(PO4)2

67

Write Chemical Formula using the charge of known ions

“Criss-Cross-Simplify”:• The charge of an ion turns into the subscript (the

number) of the counterpart ion

Pb4+ O2- Pb2O4

• Since the subscripts in an ionic compound represents the RATIO among the ions, the subscripts need to be simplified when there is common denominator

Pb2O4 PbO2

68

Practice: Writing formulas (I)

• copper(II) chloride• aluminum oxide• magnesium phosphide• iron(II) bromide• lead(II) sulfide• zinc iodide • sodium nitride

69

Hints for Writing formulas (I): Charges on Cations and Anions

• copper(II) chloride: Cu2+ and Cl-

• aluminum oxide: Al3+ and O2-

• magnesium phosphide : Mg2+ and P3-

• iron(II) bromide : Fe2+ and Br-

• lead(II) sulfide : Pb2+ and S2-

• zinc iodide : Zn2+ and I-

• sodium nitride : Na+ and N3-

70

Key for Writing formulas (I): use criss-cross-reduce

• copper(II) chloride CuCl2

• aluminum oxide Al2O3

• magnesium phosphide Mg3P2

• iron(II) bromide FeBr2

• lead(II) sulfide FeS• zinc iodide ZnI2

• sodium nitride Na3N

71

Practice: Write Chemical Formulae

• Chromium(II) Chloride • Cesium phosphate• Lead(II) oxide• Zinc nitrate• Iron(III) sulfite• Strontium nitride• Ammonium carbonate

72

Key: Write Chemical Formulae

• Chromium(II) Chloride • Cesium phosphate• Lead(II) oxide• Zinc nitrate• Iron(III) sulfite• Strontium nitride• Ammonium carbonate

CrCl2

Cs3PO4

PbO

Zn(NO3)2

Fe3(SO3)2

Sr3N2

(NH4)2CO3

73

Practice: Writing formulas (I)

• copper(I) sulfate• aluminum chlorate• magnesium phosphate• iron(II) carbonate• lead(II) acetate• zinc sulfite • sodium nitrite• Nitrogen gas

74

Hints for Writing formulas (I): Charges on Anions

• copper(I) sulfate: -2 for sulfate • aluminum chlorate: -1 for chlorate• magnesium phosphate: -3 for phosphate• iron(II) carbonate : -2 for carbonate• lead(II) acetate: -1 for acetate• zinc sulfite : -2 for sulfite• sodium nitrite: -1 for nitrite • Nitrogen gas: atomic or molecular element?

75

Key: Writing formulas (I)

• copper(I) sulfate: Cu2SO4

• aluminum chlorate: Al(ClO3)3

• magnesium phosphate: Mg3(PO4)2

• iron(II) carbonate : FeCO3

• lead(II) acetate: Pb(C2H3O2)2

• zinc sulfite : ZnSO3

• sodium nitrite: NaNO2

• Nitrogen gas: N2

76

More on Writing formulae

• copper(II) sulfate• aluminum perchlorate• hydroiodic acid• iron(III) bromide• Diphosphorus pentoxide• lead(IV) nitride• zinc carbonate • helium gas

77

Key: Writing formulae

• copper(II) sulfate CuSO4

• aluminum perchlorate Al(ClO4)3

• hydroiodic acid HI• iron(III) bromide FeBr3

• Diphosphorus pentoxide P2O5

• lead(IV) nitride Pb3N4

• zinc carbonate ZnCO3

• ammonium nitrite NH4NO2

• helium gas He