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BONDING AND NAMING 1
BONDING AND NAMING
1
2
Metals form cations and nonmetals form anions to attain a stable valence electron structure.
3
This stable structure often consists of two s and six p electrons.These rearrangements occur by losing, gaining, or sharing electrons.
4
• Na with the electron structure 1s22s22p63s1
has 1 valence electron.
The Lewis structure of an atom is a representation that shows the valenceelectrons for that atom.
• Fluorine with the electron structure 1s22s22p5
has 7 valence electrons
6
The Ionic Bond: Transfer ofThe Ionic Bond: Transfer ofElectrons From One AtomElectrons From One Atom
to Anotherto Another
7
The chemistry of many elements, especially the representative ones, is to attain the same outer electron structure as one of the noble gases.
8
With the exception of helium, this structure consists of eight electrons in the outermost energy level.
9
After sodium loses its 3s electron it has attained the same electronic structure as neon.
10
After chlorine gains a 3p electron it has attained the same electronic structure as argon.
11
Formation of NaClFormation of NaCl
12
The 3s electron of sodium transfers to the half-filled 3p orbital of chlorine.
Lewis representation of sodium chloride formation.
A sodium ion (Na+) and a chloride ion (Cl-) are formed.
The force holding Na+ and Cl- together is an ionic bond.
13
Formation of MgCl2Formation of MgCl2
14
Two 3s electrons of magnesium transfer to the half-filled 3p orbitals of two chlorine atoms.A magnesium ion (Mg2+) and two chloride ions (Cl-) are formed.The forces holding Mg2+ and two Cl- together are ionic bonds.
15
• Metals usually have one, two or three electrons in their outer shells.
• When a metal reacts it:– usually loses one two or three electrons
– attains the electron structure of a noble gas
– becomes a positive ion.
• The positive ion formed by the loss of electrons is much smaller than the metal atom.
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• Nonmetals usually have five, six or seven electrons in their outer shells.
• When a nonmetal reacts it:– usually gains one, two or three electrons
– attains the electron structure of a noble gas
– becomes a negative ion.
• The negative ion formed by the gain of electrons is much larger than the nonmetal atom.
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The Covalent Bond:The Covalent Bond: Sharing ElectronsSharing Electrons
18
A covalent bond consists of a pair of electrons shared between two atoms.
In the millions of chemical compounds that exist, the covalent bond is the predominant chemical bond.
19
Substances which covalently bond exist as molecules.
Carbon dioxide bonds covalently. It exists as individually bonded covalent molecules containing one carbon and two oxygen atoms.
11.7
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The term molecule is not used when referring to ionic substances.
Sodium chloride bonds ionically. It consists of a large aggregate of positive and negative ions. No molecules of NaCl exist.
11.7
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Covalent bonding in the hydrogen molecule
Two 1s orbitals from each of two hydrogen atoms overlap.
Each 1s orbital contains 1 electron.
The orbital of the electrons includes both hydrogen nuclei.
The most likely region to find the two electrons is between the two nuclei.
The two nuclei are shielded from each other by the electron pair. This allows the two nuclei to draw close together.
Two 1s orbitals from each of two hydrogen atoms overlap.
11.8
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11.9
Covalent bonding in the chlorine molecule
Each unpaired 3p orbital on each chlorine atom contains 1 electron.
Two 3p orbitals from each of two chlorine atoms overlap.
The orbital of the electrons includes both chlorine nuclei.
The most likely region to find the two electrons is between the two nuclei.
The two nuclei are shielded from each other by the electron pair. This allows the two nuclei to draw close together.
Two 3p orbitals from each of two chlorine atoms overlap.
Each chlorine now has 8electrons in its outermost energy level.
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hydrogen chlorine iodine nitrogen
Covalent bonding with equal sharing of electrons occurs in diatomic molecules formed from one element.
A dash may replace a pair of dots.
H - H
24
Common and Common and Systematic NamesSystematic Names
25
Chemical nomenclature is the system of names that chemists use to identify compounds. Two classes of names exist: common names and systematic names.
26
– They are not based on the composition of the compound.
– They are based on an outstanding chemical or physical property.
• Chemists prefer systematic names.– Systematic names precisely identify
the chemical composition of the compound.
– The present system of inorganic chemical nomenclature was devised by the International Union of Pure and Applied Chemistry (IUPAC).
• Common names are arbitrary names.
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28
Elements and IonsElements and Ions
29
The formula for most elements is the symbol of the element.
Sodium Na
Potassium K
Zinc Zn
Argon Ar
Mercury Hg
Lead Pb
Calcium Ca
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Hydrogen H2
Nitrogen N2
Oxygen O2
Fluorine F2
Chlorine Cl2
Bromine Br2
Iodine I2
These 7 elements are found in nature as diatomic molecules.
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Sulfur S8
Phosphorous P4
Two elements are commonly polyatomic.
32
Naming CationsNaming Cations
33
Cations are named the same as their parent atoms
34
Atom
Cation
Name of Cation
sodium (Na)
Na+
sodium ion
35
Atom
Cation
Name of Cation
calcium (Ca)
Ca2+
calcium ion
36
Atom
Cation
Name of Cation
lithium (Li)
Li+
lithium ion
37
Atom
Cation
Name of Cation
magnesium (Mg)
Mg2+
magnesium ion
38
Atom
Cation
Name of Cation
strontium (Sr)
Sr2+
strontium ion
39
Naming AnionsNaming AnionsNaming AnionsNaming Anions
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An anion consisting of one element has the stem of the parent element and an –ide ending
41
Atom
Anion
Name of Anion
Atom
Anion
Name of Anion
fluorine (F)
F-
fluoride ion
stem
42
Atom
Anion
Name of Anion
Atom
Anion
Name of Anion
chlorine (Cl)
Cl-
chloride ion
stem
43
Atom
Anion
Name of Anion
bromine (Br)
Br-
bromide ion
stem
44
Atom
Anion
Name of Anion
nitrogen (N)
N3-
nitride ion
stem
45
Atom
Anion
Name of Anion
phosphorous (P)
P3-
phosphide ion
stem
46
Atom
Anion
Name of Anion
oxygen (O)
O2-
oxide ion
stem
47
Binary CompoundsBinary Compounds
48
Binary compounds contain only two different elements.
49
Binary ionic compounds consist of a metal combined with a non-metal.
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A. Binary Ionic Compounds Containing A. Binary Ionic Compounds Containing a Metal Forming Only One Type of a Metal Forming Only One Type of
CationCation
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• The chemical name is composed of the name of the metal followed by the name of the nonmetal which has been modified to an identifying stem plus the suffix –ide.
• Using this system the number of atoms of each element present is not expressed in the name.
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Name of Metal
+ Stem of Nonmetal
plus -ide ending
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Step 1 From the formula it is a two-element compound and follows the rules for binary compounds.
Name the Compound CaF2
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Name the Compound CaF2
Step 2 The compound is composed of Ca, a metal and F, a nonmetal. Ca forms only a +2 cation. Thus, call the positive part of the compound calcium.
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Step 3 Modify the name of the second element to the stem fluor- and add the binary ending –ide to form the name of the negative part, fluoride.
Name the Compound CaF2
57
Step 4 The name of the compound is therefore calcium fluoride.
Name the Compound CaF2
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ExamplesExamples
59
Compound
Name sodiumchloride
NaCl
nonmetal stem
name of metal
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Compound
Name magnesiumchloride
MgCl2
nonmetal stem
name of metal
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Compound
Name potassiumoxide
K2O
nonmetal stem
name of metal
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Compound
Name sodiumphosphide
Na3P
nonmetal stem
name of metal
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B. Binary Ionic Compounds Containing a B. Binary Ionic Compounds Containing a
MetalMetal
That Can Form Two or More Types of That Can Form Two or More Types of
CationsCations
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Name the Compound FeS
Step 1 This compound follows the rules for a binary compound.
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Step 2 It is a compound of Fe, a metal, and S, a nonmetal, and Fe is a transition metal that has more than one type of cation.
Name the Compound FeS
Step 2 In sulfides, the charge on S is –2. Therefore the charge on Fe must be +2, and the name of the positive part of the compound is iron (II).
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Step 3 We have already determined that the name of the negative part of the compound will be sulfide.
Name the Compound FeS
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Step 4 The name of FeS is iron(II) sulfide.
Name the Compound FeS
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The metals in the center of the periodic table (including the transition metals) often form more than one type of cation.
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Each ion of iron forms a different compound with the same anion.
Fe2+
Fe3+
FeS
Fe2S3
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The Classical SystemThe Classical System
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In the Classical System the name of the metal (usually the Latin name) is modified with the suffixes -ous and ic.
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-ous lower charge
-ic higher charge
Metal name ends in
nonmetal name ends in
-ide
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Lower Charge Higher Charge
Element Formula Name Formula Name
Copper Cu+ cuprous Cu2+ Cupric
Iron Fe2+ ferrous Fe3+ ferric
Lead Pb2+ plumbous Pb4+ plumbic
Mercury Hg mercurous Hg2+ mercuric
Tin Sn2+ stannous Sn4+ stannic
Ion Names: Classical System
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Examples
75
ion chargeion name
FeCl2
ferrous chloride
+2 -1chlorideferrous
FeCl3
ferric chloride
-1+3ferric chloride
compound name
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ion chargeion name
SnBr2
stannous bromide
+2 -1bromidestannous
SnBr4
stannic bromide
-1+4stannic bromide
compound name
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The Stock SystemThe Stock System
78
IUPAC devised the Stock System of nomenclature to name compounds of metals that have more than one type of cation.
Cation Charge
+1 +2 +3 +4 +5
Roman Numeral
I II III IV V
In the Stock System the charge on the cation is designated by a Roman numeral placed in parentheses immediately following the name of the metal.
The nonmetal name ends in -ide.
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Stock SystemLower Charge Higher Charge
Element Formula Name Formula Name
Copper Cu+ copper (I) Cu2+ copper (II)
Iron Fe2+ iron(II) Fe3+ iron(III)
Lead Pb2+ lead (II) Pb4+ lead(IV)
Mercury Hg22+ mercury(I) Hg2+ mercury(II)
Tin Sn2+ Tin(II) Sn4+ Tin (II)
Stock System Higher Charge
Element Formula Name Formula Name
Lower Charge
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ExamplesExamples
81
ion chargeion name
FeCl2
iron(II) chloride
+2 -1chlorideiron(II)
FeCl3
iron(III) chloride
-1+3iron(III) chloride
compound name
82
ion chargeion name
SnBr2
tin(II) bromide
+2 -1bromidetin(II)
SnBr4
tin(IV) bromide
-1+4tin(IV) bromide
compound name
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Binary Compounds Binary Compounds Containing Two Containing Two
NonmetalsNonmetals
84
Compounds between nonmetals are molecular, not ionic.
85
In a compound formed between two nonmetals, the element that occurs first in this series is named first.
• Si
• B
• P
• H
• C
• S
• I
• Br
• N
• Cl
• O
• F
86
PrefixesPrefixes
87
A Greek prefix is placed before the name of each element to indicate the number of atoms of the element that are present.
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• di = 2
• tri = 3
• tetra = 4
• penta = 5
• hexa = 6
• hepta = 7
• octa = 8
• nona = 9
• deca = 10
• mono = 1
Mono is rarely used when naming the first element.
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ExamplesExamples
90
N2O3
dinitrogen trioxide
indicates twonitrogen atoms
indicates threeoxygen atoms
91
PCl5
phosphorous pentachloride
indicates onephosphorous atom
indicates fivechlorine atoms
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Cl2O7
dichlorine heptaoxide
indicates twochlorine atoms
indicates sevenoxygen atoms
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Step 1
• There are 2 elements present.
• The compound is binary.
• Phosphorous and chlorine are nonmetals so the rules for naming binary compounds of 2 nonmetals apply.
• Phosphorous is named first. Therefore the compound is a chloride.
Determine the Name of PCl5
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Step 2
• No prefix is needed for phosphorous because each molecule of PCl5 has only one phosphorous atom. The prefix penta- is used with chloride because there are 5 chlorine atoms present in one molecule.
Step 3
• The name is phosphorous pentachloride.
Determine the Name of PCl5
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ExamplesExamples
96
dichlorine trioxide
Cl2O3
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dinitrogen trioxide
N2O3
98
carbon tetrachloride
CCl4
99
carbon monoxide
CO
100
carbon dioxide
Name CO2
101
phosphorous triiodide
Name PI3
102
D. Acids DerivedD. Acids Derivedfrom Binary Compoundsfrom Binary Compounds
103
• Certain binary hydrogen compounds, when dissolved in water, form solutions that have acid properties.
• The aqueous solutions of these compounds are given acid names.
• The acid names are in addition to their –ide names.
• Hydrogen is typically the first element of a binary acid formula.
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Dissolved in water acidHCl
Pure compound HCl -ide
105
• To name binary acids write the symbol of hydrogen first.
• After hydrogen write the symbol of the second element.
• Place the prefix hydro- in front of the stem of the nonmetal name.
• Place the suffix -ic after the stem of the nonmetal name.
106
ExamplesExamples
107
HClhydrogen chloride
Pure Compound
108
HClhydrochloric acid
Dissolved in Water
109
HIhydrogen iodide
Pure Compound
110
HIhydroiodic acid
Dissolved in Water
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H2Shydrogen sulfide
Pure Compound
112
H2Shydrosulfic acid
Dissolved in Water
113
H2Sehydrogen selenide
Pure Compound
114
H2Sehydroselenic acid
Dissolved in Water
115
116
Naming Compounds Naming Compounds
Containing Polyatomic IonsContaining Polyatomic Ions
117
A polyatomic ion is an ion that contains two or more elements.
-3NO
118
2 3Na CO
• They usually consist of one or more cations combined with a negative polyatomic ion.
• Compounds containing polyatomic ions are composed of three or more elements.
119
• When naming a compound containing a polyatomic ion, name the cation first and then name the anion.
2 3Na CO
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4KMnO
+K -4MnO
The ions are what isactually present.
This is the way theformula is written.
121
This is the way theformula is written.
2 3Na CO
The ions are what isactually present.
+2Na 2-3CO
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Prefixes and SuffixesPrefixes and Suffixes
Elements that Form More than Elements that Form More than One Polyatomic Ion with One Polyatomic Ion with
OxygenOxygen
123
Anions ending in -ate always contain more oxygen than ions ending in -ite.
nitrate-3NO
nitrite-2NO
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Anions ending in -ate always contain more oxygen than ions ending in -ite.
phosphate3-4PO
phosphite-3PO
125
Anions ending in -ate always contain more oxygen than ions ending in -ite.
sulfate2-4SO
sulfite-3SO
-ate and –ite do not indicate the number of oxygen atoms.
126
per- denotes anions with more oxygen than the -ate form.
perchlorate-4ClO
chlorate-3ClO
128
hypo- denotes anions with less oxygen than the -ite form.
Chlorite-3ClO
hypochlorite-ClO 2
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Four ions do not use the –ate/ite system.
hydroxide-OH
hydrogen sulfide-HS
cyanide-CN
peroxide2-2O
131
There are three common positively charged polyatomic ions.
ammonium+4NH
hydronium+
3H O
mercury(I)2+2Hg
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AcidsAcidsAcidsAcids
134
• The other element is usually a nonmetal, but it can be a metal.
• Its first element is hydrogen.
• Its remainingelements include oxygen and form a polyatomic ion.
Oxy-acids contain hydrogen, oxygen and one other element.
135
Hydrogen in an oxy-acid is not expressed in the acid name.
The word acid in the name indicates the presence of hydrogen.
136
contains oxygen
contains sulfur
contains hydrogen
indicates hydrogen
sulfuric acid 42SOH
137
Anions ending in -ate always contain more oxygen than ions ending in -ite.
phosphate3-4PO
phosphite-3PO
138
Naming the Acid Based on the Name of the Polyatomic Ion
Ending of Polyatomic Ion
more oxygen
less oxygenite
ate
Ending of Acid
ous
ic
139
ExamplesExamples
140
sulfite23SO
sulfurous acid 2 3H SO
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sulfate24SO
sulfuric acid 2 4H SO
142
nitrite 2NO
nitrous acid 2HNO
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nitrate 3NO
nitric acid 3HNO
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