Naming & Calculating Naming & Calculating Chemical CompoundsChemical Compounds

Unit3 – Lecture 2

Recap – Bonding Occurs…Recap – Bonding Occurs…

• …to fill the outer level of electrons of elements

• you can predict bonding by observing trends on the periodic table:

• type of element: metals, non metals, etc• valence electrons: for lewis diagrams• oxidation #: criss-cross method

Counting AtomsCounting Atoms

• A Chemical Formula shows how many of which atoms are in a molecule

• A Subscript is a number placed below and behind a symbol to show how many of which atoms are present

H2O

Counting AtomsCounting Atoms

• A Coefficient is placed in front of a molecule to show more than one molecule 3H2O

Counting AtomsCounting Atoms

• A Diatomic Molecule shows two atoms of the same nonmetal (usually in gas form) that have bonded together

• Reactive nonmetals will bond with one another if no other substance is available for bonding

HH22 NN22

OO22 FF22

II22 ClCl22BrBr22

Polyatomic IonsPolyatomic Ions

• A group of atoms that behave as one atom

• Keep together as a unit• Listed on p. 619• If more than one

polyatomic ion is present in a molecule, parentheses set it apart• Still use a subscript to

show how many

Ca(OH)2

NH4Cl

Oxidation NumbersOxidation Numbers

• A positive or negative sign used to show what type of ion is formed after an atom has gained or lost enough electrons to be chemically stable

• Written like a charge sign (upper right)

• Always included with a list of polyatomic ions

BASE OXIDATION NUMBERS BY GROUP

+1 0

+2 +3 ±4 -3 -2 -1

USE ROMAN NUMERALS

Oxidation #s – cont’dOxidation #s – cont’d• Transition metals have more than one

oxidation number!!!!• Fe[III] = Fe+3 = Iron with +3 oxidation number• Fe[II] = Fe+2 = Iron with +2 oxidation number

• Mn[II] = Mn+2 = Manganese with +2 oxidation number

• Mn[III] = Mn+3 = Manganese with +3 oxidation number

Making Formulae – Making Formulae – the “Criss-Cross” Methodthe “Criss-Cross” Method

• cation first – write element & oxidation #• anion next – write element & oxidation #• without the + or – sign

• write the oxidation # from one symbolon the other as a subscript

• remember to add parentheses aroundpolyatomic ions

• don’t write the #1, it is implied• reduce any evenly-divisible subscripts

Practice Practice What is the correct formula for a bond between… Carbon and Hydrogen?

1.CH C2H2 CH3

2.C2H3 CH4

Sodium and Nitrogen?

1.NaN Na2N2Na3N

2.Na2N3 Na3N4

Calcium and Chlorine?

1.CaCl Ca2Cl2 Ca2Cl

2.CaCl2 Ca3Cl4

Practice – cont’dPractice – cont’dWhat is the correct formula for a bond

between… Sodium and Hydroxide (OH) ?

[hint: figure out the leftover charge from combining an oxygen an a hydrogen]

1.NaOH Na(OH)2 Na(OH)3

2.Na2(OH)3 Na(OH)4

Aluminum and Sulfate (SO4) ?1.AlSO4 Al2(SO4)2 Al2(SO4)3

2.Al3(SO4)3 Al(SO4)4

Binomial NomenclatureBinomial Nomenclature

• Naming a two-part name

• Used to differentiate between Fluorine (an element) and Fluoride (part of a compound)

• Never change the name of a Polyatomic Ion• Big difference between Sulfide and Sulfite

Naming Ionic CompoundsNaming Ionic Compounds

• List the positive ion (or metal) first• ***Use Roman Numerals to show the Oxidation

number of a transition metal

• Name the negative ion (or nonmetal), changing the ending to –ide• “Oxide”

• “Sulfide”

• “Phosphide”

• Ex: FeO / Fe2O3

• = Iron II Oxide / Iron III Oxide

Naming Polyatomic Naming Polyatomic CompoundsCompounds

• Compound is polyatomic if there are more than 2 elements You will be given the names for common polyatomics.

Still only 2 words in the name• first term = positive ion name • second term = negative ion name

• if second term is NOT a polyatomic, change ending to -ide

• if the second term is a negative polyatomic, do NOT change the ending

Naming Covalent CompoundsNaming Covalent Compounds• Prefixes are used to show how many of which

atoms• = number terms from Greek / Latin

• Write the name of the cation [or most positive]• only add a prefix for the first atom if

there is more than one

• Write the name of the anion [or most negative]• add a prefix to tell how many are present• change the ending to -ide

Covalent CompoundsCovalent Compounds

• Prefixes are used to show how many of which atoms

• Prefixes are number-words from Greek & Latin

• Write the name of the first atom• Add a prefix only if there is more than one of the

first• Write the name of the second atom

• Add a prefix showing how many of the second are present

• Change the ending to -ide

Numbering PrefixesNumbering Prefixes

1 – Mono-

2 – Di-

3 – Tri-

4 – Tetra-,

5 – Penta-

6 – Hexa-

7 – Hepta-

8 – Octa-

9 – Nona-

10 – Deka-

What is the name for NWhat is the name for N22OO44??

1. Nitrogen Oxide

2. Dinitrogen Oxide

3. Dinitrogen Dioxide

4. Dinitrogen Tetraoxide

5. Nioxx (Nioxalate)

What is the name for NaWhat is the name for Na22S?S?

1. Sodium Sulfide

2. Sodium Sulfite

3. Sodium Sulfate

4. Disodium Sulfide

5. Disodium Sulfate

What is the name for What is the name for COCO22??

1. Carbon Oxide

2. Carbon Dioxide

3. Monocarbon Oxide

4. Monocarbon Dioxide

5. Mi-Bref (B-hot)

What is the name for (What is the name for (NHNH44))22O?O?

1. Nitrogen Hydrogen Oxide

2. Mononitrogen Tetrahydrogen Oxide

3. Ammonium Oxide

4. Diammonium Oxide

5. Ammonium Oxalate

Practice Practice

• What is the name for N2O4?• non-metal + non-metal…so covalent

• Dinitrogen Tetraoxide

• What is the name for Na2S?• metal + non-metal = ionic

• Sodium Sulfide

• What is the name for CO2?• non-metal + non-metal = covalent

• Carbon Dioxide

Practice – cont’dPractice – cont’d

• What is the name for (NH4)2O?[hint: you need to know what (NH4) is…]• Nitrogen Hydrogen Oxide• Mononitrogen Tetrahydrogen Oxide• Ammonium Oxide• Diammonium Oxide• Ammonium Oxalate

CORRECT!!!!

Practice – cont’dPractice – cont’d