Transcript name - Fulton County Schools

Naming & Calculating
Chemical Compounds
Unit3 – Lecture 2
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 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 Atoms
• A Coefficient is
placed in front of a
molecule to show
more than one
molecule
3H2O
Counting 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
H2 N2
O2 F2
I2 Cl2
Br2
Polyatomic 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 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
+3 ±4 -3 -2 -1
+2
USE ROMAN NUMERALS
Oxidation #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 –
the “Criss-Cross” Method
• cation first – write element & oxidation #
• anion next – write element & oxidation #
• without the + or – sign
• write the oxidation # from one symbol
on the other as a subscript
• remember to add parentheses around
polyatomic ions
• don’t write the #1, it is implied
• reduce any evenly-divisible subscripts
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
Na2N2
2.
Na2N3
Na3N4
Na3N
 Calcium and Chlorine?
1.
CaCl
Ca2Cl2
2.
CaCl2
Ca3Cl4
Ca2Cl
Practice – cont’d
What 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.
2.
NaOH
Na(OH)2 Na(OH)3
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 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 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
Naming Polyatomic
Compounds
• 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 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 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 Prefixes
1 – Mono2 – Di3 – Tri4 – Tetra-,
5 – Penta-
6 – Hexa7 – Hepta8 – Octa9 – Nona10 – Deka-
What is the name for N2O4?
1.
2.
3.
4.
5.
Nitrogen Oxide
Dinitrogen Oxide
Dinitrogen Dioxide
Dinitrogen Tetraoxide
Nioxx (Nioxalate)
What is the name for Na2S?
1.
2.
3.
4.
5.
Sodium Sulfide
Sodium Sulfite
Sodium Sulfate
Disodium Sulfide
Disodium Sulfate
What is the name for CO2?
1.
2.
3.
4.
5.
Carbon Oxide
Carbon Dioxide
Monocarbon Oxide
Monocarbon Dioxide
Mi-Bref (B-hot)
What is the name for (NH4)2O?
1.
2.
3.
4.
5.
Nitrogen Hydrogen Oxide
Mononitrogen
Tetrahydrogen Oxide
Ammonium Oxide
Diammonium Oxide
Ammonium Oxalate
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’d
• What is the name for (NH4)2O?
[hint: you need to know what (NH4)
is…]
•
•
•
•
•
Nitrogen Hydrogen
Oxide
CORRECT!!!!
Mononitrogen Tetrahydrogen Oxide
Ammonium Oxide
Diammonium Oxide
Ammonium Oxalate
Practice – cont’d
Al2S3
CrO
Lead (II) oxide
PbO2
(NH4)2S
Ca(OH)2
Iron (II) cyanide
Fe(NO3)3
Aluminum sulfide
Chromium (II) oxide
PbO
Lead (IV) oxide
Ammonium sulfide
Calcium hydroxide
Fe(CN)2
Iron (III) nitrate