Bonding
p. 97-106
• chemical bond: interaction between
atoms or ions
–decreases the potential energy of an
atom; makes it more stable
–only the valence electrons are involved!
Three Types of Bonds
• Bond type depends on electronegativity
(electron affinity)
–IONIC：very different electronegativities
• one metal, one non-metal
–COVALENT: both very high
• two non-metals
–METALLIC: both low
• one or more metals
Review of Ionisation
+1
+2
-3 -2 -1
Anions
Cations
Metals
Nonmetals
What kind of bond?
•
•
•
•
•
•
•
•
Na and Cl
O and F
K and Br
Au and Ag
H and O
Mg and F
S and Cl
Ni and Cu
•
•
•
•
•
•
•
•
Ionic
Covalent
Ionic
Metallic
Covalent
Ionic
Covalent
Metallic
Ionic Bonds
• metal (low electroneg., cation) + nonmetal (high electroneg., anion)
• Array of positively and negatively
charged ions
–held together by electrostatic attraction
• metal loses e- = cation
–group 1 (+1) and group 2 (+2)
–transition metals (+2 most common)
• non-metal gains e- = anion
–groups 17, 16, 15…
• List, p. 100
sodium and chlorine
Na
Cl
• sodium transfers its electron to
chlorine
Crystal Lattice (Array)
• structure of an ionic bond
• each anion is surrounded by cations
and vice versa
Writing Formulae for
Ionic Compounds
• chemical formula: shorthand for
elements, ions and compounds
• Ratio of the number of atoms of each
element
–MgCl2
–C6H12O6
• Ions of opposite charges are attracted
to one another.
• Mg2+
Cl• MgCl2
• Ions bond because they are electrically
attracted to one another
–“Opposites attract”
• Polyatomic ions: most covalently
bonded, but have an overall electronic
charge
• Hand out list: memorize it.
Ionic or Covalent?
•
•
•
•
•
NaCl
NO2
N2Br
NaI
CaS
Ionic or Covalent?
•
•
•
•
•
KNO3
Fe(CrO4)2
Cu(OH)2
BaI
F2
Ionic or Covalent?
• O2
• AgCl
• AgNO3
Ionic or Covalent?
•
•
•
•
•
NO2
CO2
PCl5
P2S4
NO3
Writing Formulae for
Ionic Compounds
• Write the symbols and their charges
• “Cross” the charges to the other side
• Use the charges, without + or – as
subscripts
Polyatomic Ions to Memorize
•
•
•
•
•
•
•
•
Ammonium
Nitrite
Nitrate
Sulfite
Sulfate
Hydroxide
Phosphite
phosphate
•
•
•
•
Carbonate
Chlorite
Chlorate
Chromate
Naming Ionic
Compounds
Naming Cations
• Same as the element!!
Naming Anions
•
•
•
•
•
•
•
Ending changes to “ide”
O
oxygen
oxide
F
fluorine
fluoride
S
sulfur
sulfide
Cl
chlorine
chloride
Br
bromine
bromide
I
iodine
iodide
•
•
•
•
•
•
Chlorine
Iodine
Oxygen
Sulfur
Bromine
Fluorine
•
•
•
•
•
•
Chloride
Iodide
Oxide
Sulfide
Bromide
Fluoride
Naming Ionic Compounds
• Cation + Anion (“ide” ending)
• NaCl
sodium chloride
• KBr
potassium bromide
Naming Ionic Compounds –
Type I
• One positively charged ion and one
negatively charged ion.
• NaCl
–Sodium chloride
• SrF2
–Strontium fluoride
1.
2.
3.
4.
5.
6.
7.
1.
CsBr
2.
MgO
3.
KF
4.
AlCl3
5.
LiH
calcium iodide 6.
rubidium sulfide 7.
cesium bromide
magnesium oxide
potassium fluoride
aluminum chloride
lithium hydride
CaI2
Rb2S
•
•
•
•
•
•
•
LiI
CaS
AgBr
ZnCl2
Na2S
barium fluoride
silver oxide
•
•
•
•
•
•
•
lithium iodide
calcium sulfide
silver bromide
zinc chloride
sodium sulfide
BaF2
Ag2O
Stock system
• Some elements make ions with
different charges (p. 100)
–“oxidation states”
• Fe2+
Fe3+
• iron(II)
iron(III)
• Roman numerals
Elements that use the
Stock System
• These elements have more than one
“oxidation state”
–Fe (2+, 3+)
Cr (2+, 3+)
–Cu (1+, 2+)
Mn (2+, 3+)
–Co (2+, 3+)
Pb (2+, 4+)
–Sn (2+, 4+)
–Hg2+ (mercury II), Hg22+ (mercury I)
–Zumdahl, p. 65
Ions to memorize
•
•
•
•
Al3+
Zn2+
Ag+
Cd2+
1.
2.
3.
4.
5.
6.
7.
• copper (I) chloride
CuCl
• tin (II) oxide
SnO
• iron (III) oxide
Fe2O3
• manganese (IV) oxide
MnO2
• lead (II) chloride
PbCl2
• Cu2O3
copper (III) oxide
vanadium (IV) fluoride • VF4
1.
2.
3.
4.
5.
6.
CoBr2
CrCl3
CaCl2
Al2O3
SnBr4
Cu2S
cobalt (II) bromide
chromium (III) chloride
calcium chloride
aluminum oxide
tin (IV) bromide
copper (I) sulfide
7. iron (II) fluoride • FeF
2
8. tin (II) oxide
• SnO
•
•
•
•
•
•
• Fe(NO3)3
–Iron(III) nitrate
• Fe2(SO4)3
–iron(III) sulfate
Polyatomic
Ion
Ionic Compounds with Polyatomic
Ions
• NH4+
–ammonium
• NO3–nitrate
1.
2.
3.
4.
5.
6.
7.
Na2SO4
1.
KH2PO4 2.
Fe(NO3)3 3.
Mn(OH)2 4.
Na2SO3
5.
Rb2CO3
6.
Mg(HCO3)27.
sodium sulfate
potassium dihydrogen phosphate
iron (III) nitrate
manganese (II) hydroxide
sodium sulfite
rubidium carbonate
magnesium bicarbonate
•
•
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•
Name Ionic Compounds
potassium nitrate
magnesium hydroxide
lithium chromate
iron (III) hydroxide
cobalt nitrate
Manganese (II) posphite
•
•
•
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•
•
KNO3
Mg(OH)2
LiCrO4
Fe(OH)3
Co(NO3)2
Mn3(PO3)2
Homework
1. CaO
2. lithium sulfide
3. CrCO3
4. silver iodide
5. Cu2SO3
6. calcium phosphate
7. SrI2
8. iron (III) bromide
9. FeBr2
10.cobalt (II) iodide
11.SnO2
12.ammonium nitrate
13.Ag2S
Covalent Bonding
Covalent Bonding
• two or more non-metals
• atoms share some valence electrons
(not transfer)
• single covalent bond: shares one pair
of electrons
• double: 2 pairs of e• triple: 3 pairs of e-
• usually each atom donates (shares)
one of each pair of electrons
• dative covalent bond: sometimes one
atom donates both electrons
F
F
Electron Pair
Shared by both atoms
Each e- donate by each atom
• number of bonds formed depends on
the number of e- required to fill the
valence shell
–noble gases = full valence, rarely form
compounds
• octet rule: usually, atoms want 8
valence e- (H, He need 2)
• Ex: C has 4 valence e–needs 4 more to form a full octet
–C forms 4 bonds
• Ex: F has 7 valence e–needs 1 more to form a full octet
–F makes one bond
• Nitrogen?
Bonding between C and F
F
F
F C F F C F
F
F
structural
formula
hybrid
diagram
=e- pair
=covalent bond
F
F C F
F
Lewis
diagram
F e - C e-
Double Bond
• sharing two pairs of electrons
• bonds more strongly than a single bond
O C O O C O O C O
• structural
hybrid
Lewis
Triple Bond
• Strongest
N N
N N
N N
Length and Strength of Bonds
single
longest
lowest energy
double
triple
shortest
highest energy
Drawing molecule diagrams
1. Decide how many bonds each atom
makes.
2. The central atom is the one that
makes the most bonds.
3. Draw with single bonds
4. Calculate remaining electrons
5. Use remaining electrons
• HCN (hydrogen cyanide)
–C=4, N=3, H=1
• HCO2- (methanoate ion)
–H=1, C=4, O=2
Draw structural, hybrid and
Lewis structures
•
•
•
•
•
HF
NH3
CH4
CF4
NO2-
•
•
•
•
CHCl3
NH4+
H2CO
SeF2
Naming Covalent Compounds
• Ex: CO2
–carbon dioxide
• Prefixes
–mono 1
–di
–tri
–tetra
–penta 5
–hexa
2
3
4
6
1.
2.
3.
4.
5.
6.
N2O
NO
NO2
N2O3
N2O4
N2O5
1.
2.
3.
4.
5.
6.
Phosphorus pentachloride
Phosphorus trichloride
Sulfur hexafluoride
Sulfur trioxide
Sulfur dioxide
Carbon dioxide
•
•
•
•
•
P4O10
Fe2O3
Li2O2
Mg(NO3)2
CCl4
•
•
•
•
•
tetraphosphorus decoxide
iron (III) oxide
lithium peroxide
Magnesium nitrate
Carbon tetrachloride
Homework
•
•
•
•
•
NI3
SF2
N2O4
ICl3
SF6
phosphorus trichloride
dinitrogen tetrafluoride
sulfur dioxide
diphosphorus pentasulfide
dihydrogen monoxide
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