Classifying

1
Classifying Naming Matter

• Criteria for Classification
• Level of complexity
• Elements vs compounds
• Physical and chemical properties
• State at STP, melting points, color, hardness
• Types of reactions
• Families of compounds
• Formation of ions
• Type of bonding
• Requires structural information
• Overlapping criteria
• Substances can be classified very specifically or
  very generally and these classifications may
  overlap
• NaCl (sodium chloride) is
• a chloride a soluble salt an ionic compound
• Specific ? general

2
Classifying Element by Type of Bonding
ELEMENTS
Is the element a metal?
METALLIC NETWORK BONDING
Examples Na, Al, Pb, Hg, Cr, Ca, U
MOLECULAR COVALENT ELEMENTS
NETWORK COVALENT ELEMENTS
COVALENT BONDING
COVALENT BONDING
Examples O2, S8, Cl2, P4
Examples C, Si, B
3
Classifying Compounds by the Type of Bonding
COMPOUNDS
Is the front of the formula NH4 or a metal that
has an oxidation number less than or equal to 3?
IONIC (CRYSTAL LATTICE) BONDING
Examples NaCl, (NH4)2Cr2O7, Al2O3, Mg(NO3)2,
PbSO4, Fe2(CO3)3, KClO3
NETWORK COVALENT COMPOUNDS
MOLECULAR COVALENT COMPOUNDS
COVALENT BONDING
COVALENT BONDING
Examples SiO2, PbO2, SnO2, V2O5, CrO3, SiC
Examples CO2, H2SO4, HBr, CCl4, Cl2O5,
NH3 C6H12O6, C500H880N120O166S12 (a protein)
4
Three Important Rules

• Primary Formula Rule almost all empirical
  formulas read left to right from least to most
  electronegative element in the substance
• Primary Naming Rule the most important factor in
  naming chemicals is determining the region of the
  PT for the first element in the formula
  (sometimes the first group)
• Primary Reaction Rule many chemical units
  (species) are retained in reactions
• Oxidation reduction reactions are an exception
  we will briefly discuss later
• This helps in balancing reaction equations

5
Facts about Compounds

• Ionic compounds (also on slide 13 of PP chapter 4
  in notes)
• Always solids
• Ions are present but are immobilized in crystals
• Presence of ions is established by conductivity
  of molten or dissolved compounds
• Covalent compounds
• Solids, liquids, gases
• Generally size dependent but not always larger
  tend to be solids (reasons later)
• Network covalent are generally very hard
• Size of network can vary
• Melting of network compounds destroys substance
  whereas melting of molecular is usually reversible

6
Matter containing charges

• Some matter comes in charged units
• Ionic network substances
• Some matter comes in neutral units that cannot
  become charged
• Many network covalent and molecular covalent
  substances
• Some matter comes in neutral units that can carry
  charge or can become charged
• Metals charge carriers (no additional coverage)
• Ionizable molecular substances (reasons later)
• How do we know that matter has charged units?
• Add it to water and if it dissolves, and if the
  solution can conduct electricity (to any extent),
  charges are present
• If the substance does not dissolve in water, melt
  it if the molten substance can conduct
  electricity, charges are present

7
Oxidation number and charges

• Charges are a subset of oxidation numbers
• Oxidation numbers apply ONLY to individual atoms
  of elements in the elemental or combined form
• Charges apply to monatomic and polyatomic units
  called ions
• Metal oxidation numbers of 1, 2, 3 correspond
  to charges of 1, 2, 3
• Nonmetal oxidation numbers of -1, -2, -3
  correspond to charges of 1-, 2-, 3- ONLY when the
  nonmetal is in a binary compound with a metal
• NaCl Na has a charge of 1 Cl has a charge of
  1-
• NaClO4 Na has a charge of 1 BUT Cl and O are
  not charged ClO4 as a unit has a charge of 1-

8
Common Sense Rules for Oxidation Numbers

• The oxidation number of atoms in elements is
  always 0 (ZERO)
• If there is only one element present in a formula
  (no matter how many atoms there are in the
  formula), the atoms are in the elemental state
• The oxidation number for oxygen in compounds for
  our purposes is ALWAYS -2
• THERE ARE EXCEPTIONS THAT WE WILL NOT WORRY ABOUT
• This fact helps determine oxidation numbers of
  other atoms in lots of compounds (especially
  compounds with transition metals)
• The oxidation number for hydrogen in compounds
  for our purposes is ALWAYS 1
• ALSO EXCEPTIONS THAT WE WILL NOT WORRY ABOUT
• Other oxidation numbers are usually the common
  charges formed by atoms when they form ions (Na,
  S2-)
• EXCEPT WHEN O (oxygen) IS PRESENT IN POLYATOMIC
  UNITS OR WITH TRANSITION METALS, METALLOIDS,
  NONMETALS Sn, Pb
• All oxidation numbers (and charges on transition
  metals) can be determined by difference (in most
  cases) using these rules

9
Nature of Charged Units (partial review)

• Charges come in positive () units and negative
  (-) units that cancel each other out ions
• Positive units cations Negative units anions
• Anions are present ONLY if there are cations
• Atoms of elements with charge monatomic ions
• Groups of atoms with charge polyatomic ions
• Polyatomic units do NOT come apart and the charge
  is associated with the entire unit
• Polyatomic units are put together covalently!
• Charges indicate the ACTUAL electron excess (-)
  or deficit () on a chemical species
• Oxidation numbers indicate the hypothetical
  electron excess or deficit if all available
  electrons were transferred to the more
  electronegative element

10
Ways to get FREE ions

• Dissociation
• From dis associate to no longer be associated
  to produce FREE ions from ions that already
  existed in association
• Network Ionic substances can dissociate
• Ionization
• ation the act of therefore the act of
  forming ions an act requires an action!
• Forming ions where there were none previously by
  some action
• Some molecular substances can ionize
• Ionization can be complete (strong electrolyte)
  or partial (weak electrolyte)
• ASSUME CONDITIONS FOR COMPLETE ION FORMATION AT
  THIS TIME

11
Ways to get FREE ions
Ionization (acid) (most common)

• Dissociation

XY
Y-
HA
A-
NaCl
Cl-
HCl
Cl-
Na2SO4
SO42-
HNO3
NO3-
X
H
Na
2 Na
IONS ALREADY PRESENT
IONS NOT PRESENT
12
Understanding Formulas - 1

• Binary Formulas (AxBy)
• There are x number of A and y number of B
• Na2O 2 Na atoms, 1 O atom (1 is never shown)
• Al2O3 2 Al atoms, 3 O atoms
• In both these cases the atoms exist as and are
  organized as ions
• 2 Na O2- 2 Al3 3 O2-
• CO2 1 atom of C, 2 atoms of O
• P2O5 2 atoms of P, 5 atoms of O
• In both these cases the atoms are connected by
  covalent bonds
• Lewis structures can be made
• You should be able to make the one for CO2 (P2O5
  requires knowing more)

13
Understanding Formulas - 2

• Ternary Formulas no brackets AxByCz
• There are x number of A, y number of B, z number
  of C
• NaNO3 1 atom of Na, 1 atom of N, 3 atoms of O
• K2SO4 2 atoms of K, 1 atom of S, 4 atoms of O
• In both these cases the atoms exist as and are
  organized as ions BUT one of the ions is simple,
  the other is complex (polyatomic ion)
• Na NO3- 2 K SO42-
• The polyatomic ions are put together covalently
  and carry a charge because electrons have been
  borrowed (for these negative ions)
• The electrons have come from the metal atoms
  forming cations
• H3PO4 3 atoms of H, 1 atom of P, 4 atoms of O
• C6H12O6 6 atoms of C, 12 atoms of H, 6 atoms of
  O
• In both these cases the atoms are connected by
  covalent bonds
• Lewis structures can be made
• You should be able to make the one for H3PO4
  (C6H12O6 requires knowing more)

14
Understanding Formulas - 3

• Ternary Formulas with brackets Ax(ByCz)w Less
  commonly (AxBy)wCz
• For Ax(ByCz)w there are x number of A atoms AND w
  number of ByCz groups each consisting of y atoms
  B and z atoms of C
• Ca(NO3)2 1 atom of Ca, 2 groups of NO3 each
  with 1 atom of N, 3 atoms of O
• Fe2(SO4)3 2 atoms of Fe, 3 groups SO4 each of 1
  atom of S, 4 atoms of O
• In both these cases the atoms exist as and are
  organized as ions BUT one of the ions is simple,
  the other is complex (polyatomic ion)
• Ca2 2 NO3- 2 Fe3 3 SO42-
• The polyatomic ions are put together covalently
  and carry a charge because electrons have been
  borrowed (for these negative ions)
• The electrons have come from the metal atoms
  forming ions
• (NH4)2SO4 2 groups of NH4 each of 1 atom of N,
  4 atoms of H and 1 group of SO4 with 1 atom of S,
  4 atoms of O
• In this case the atoms exist as and are organized
  as ions both of which are polyatomic
• 2 NH4 SO42-
• Both polyatomic ions are put together covalently
  and carry a charge because electrons have been
  donated from one group to the other
• THERE ARE NO EXAMPLES OF THIS KIND OF FORMULA FOR
  COVALENT COMPOUNDS

15
Spotting substances (from their formulas) that
can dissociate or ionize

• What we need to know
• Where to split formulas into potential and
  ions
• Oxidation numbers of atoms in formulas
• How to determine oxidation numbers by difference
• A procedure to follow
• Formulas we have encountered
• Binary (2 elements)
• Ternary (3 elements)
• Quaternary (4 elements) (only a few of these)

16
BINARY OR TERNARY FORMULA
Is the first element in the formula a metal?
Is the oxidation number of the first element gt 3
?
Is the first element H?
17
K2SO4
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
2 K SO4 2-
18
SnO2
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
19
H3PO4
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
3 H PO4 3-
20
Cl2O5
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
21
Mg3(PO4)2
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
3 Mg2 2 PO4 3-
22
CrO3
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
23
ZnI2
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
Zn2 2 I-
24
LiMnO4
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
Li MnO4 -
25
Ca3N2
Is the first element in the formula a metal?

Is the oxidation number of the first element gt 3
?
Is the first element H?

Give each H in the formula a 1 charge give the
rest of formula a negative charge that cancels
the total positive charge
3 Ca2 2 N 3-
26
Naming Chemicals

• The most important factor in naming chemicals is
  determining the region of the PT for the first
  element in the formula (sometimes the first
  group)
• This dictates the kind of naming used
• The first name for a chemical is usually the
  name of the first element in formula
• The last name for a chemical is usually an
  altered form of an elemental name or a unique
  name for a group of atoms that have a fixed
  number of atoms and a fixed charge

27
A Guide for Naming
Names for Binary Formulas (XaYb)
Is X a metal?
Is the front half element in Group 1,2,3,13?

YES
NO
Prefix element name of X prefix stem name of
element Y IDE
NO
YES
Element name of X stem name of element Y IDE
Element name of X (Roman numeral of ox of X)
stem name of element Y IDE
Prefix Names 1 mon(o) 2 di 3 tri 4
tetr(a) 5 pent(a) 6 hex(a)
mono is NEVER used with the first name of the
formula
28
A Guide for Naming
Names for Ternary Formulas XaYbZc
Is X a metal?
Is the front half element in Group 1,2,3,13?

YES
NO
NO
YES
Prefix element name of X group name for YbZc
Element name of X group name for YbZc
Element name of X (Roman numeral of ox for X)
group name for YbZc
Prefix Names 1 mon(o) 2 di 3 tri 4
tetr(a) 5 pent(a) 6 hex(a)
mono is NEVER used with the first name of the
formula
29
Polyatomic Ions

• Characteristics
• Ions that contain more than one type of element
• Most important polyatomic ions are oxyanions
• These contain 1 atom of another element, 1 to 4
  atoms of O and a negative charge from -1 to -3
• Three unique polyatomic ions
• Hydroxide OH- cyanide CN- ammonium NH4
• Origins
• All negative polyatomic ions arise from partial
  or complete ionization of acids (loss of H)
• The H usually comes from an O-H bond in the
  Lewis structure
• Positive polyatomic ions arise by the addition of
  H to neutral species
• Usually the H forms a bond with an N or O atom
  in the Lewis structure

30
Formation of polyatomic ions
Generalized ionization
Specific ionizations
Complete ionization all Hs are released as H
A-
HA
SO42-
CN-
HCN
H2SO4
PO43-
H3PO4
H
H
2 H
3 H
Partial ionization some of Hs are released as H
H2SO4
HSO4-
HPO42-
H3PO4
H
2 H
H
Formation of positive ions by addition of H
B
NH3
H
NH4
HB
31
Names of Polyatomic Ions (Oxyanions)
Oxidation of other atom (not O)

• 5 or 6 ? stem name ate
• ClO3- chlor ate
• SO42- sulf ate
• PO43- phosph ate
• NO3- nitr ate

• 3 or 4 ? stem name ite
• ClO2- chlor ite
• SO32- sulf ite
• PO33- phosph ite
• NO2- nitr ite

Exception CO32- (C is 4) carbonate

• If hydrogens are present on polyatomic ion,
  precede the name of polyatomic ion by hydrogen
  if two hydrogens by dihydrogen
• HCO3- hydrogen carbonate
• H2PO4- dihydrogen phosphate

32
A Guide for Naming
Na3P
Binary or ternary ?
Sodium
ide
phosph
33
A Guide for Naming
CrO3
Binary or ternary ?
Chromium
ide
ox
(VI)
34
A Guide for Naming
Binary or ternary ?
Co2(CO3)3
Cobalt
carbonate
(III)
35
A Guide for Naming
Br2O3
Binary or ternary ?
Di
ide
ox
bromine
penta
36
A Guide for Naming
H2S
Binary or ternary ?
hydrogen
ide
sulf
Di
37
A Guide for Naming
Binary or ternary ?
Ni(NO3)2
Nickel
(II)
nitrate
38
A Guide for Naming
Binary or ternary ?
Ca(NO3)2
Calcium
nitrate
39
A Guide for Naming
Fe2O3
Binary or ternary ?
Iron
ide
ox
(III)
40
A Guide for Naming
Binary or ternary ?
HClO3 (g)
Hydrogen
chlorate
41
A Guide for Naming
Binary or ternary ?
Mn(ClO2)3
Manganese
chlorite
(III)
42
A Guide for Naming
Ca3N2
Binary or ternary ?
Calcium
ide
nitr
43
A Guide for Naming
Binary or ternary ?
Na2HPO4
Quaternary for hydrogen oxyanions same rules as
ternary
Sodium
hydrogen phosphate
44
A Guide for Naming
Binary or ternary ?
H2SO4 (l)
Di
hydrogen
sulfate
45
A Guide for Naming
AlCl3
Binary or ternary ?
Aluminum
ide
chlor