Chapter 3 Chemical Bonds Chemistry B11
Chapter 3
Chemical Bonds
Chemistry B11
1. Ionic bonds
2. Covalent bonds
3. Metallic bonds
4. Hydrogen bonds
5. Van der Waals forces
Chemical Bonds
1. Ionic bonds
2. Covalent bonds
Chemical Bonds
Review
Shell 1
Main-group elements
1A – 8A
Maximum 2 electrons in valence shell
Hydrogen and Helium
Other Shells Maximum 8 electrons in valence shell
Octet rule
Goal of atoms Filled valence shellNoble gases
(Stable)
Na+: 1s2 2s2 2p6
+ e-
Na: 1s2 2s2 2p6 3s1 Ne: 1s2 2s2 2p6
Ar: 1s2 2s2 2p6 3s2 3p6
Octet rule
Goal of atoms Filled valence shell
+ e-
Ar: 1s2 2s2 2p6 3s2 3p6
Noble gases (Stable)
Cl: 1s2 2s2 2p6 3s2 3p5 Cl-: 1s2 2s2 2p6 3s2 3p6
Na+: 1s2 2s2 2p6
+ e-
Na: 1s2 2s2 2p6 3s1 Ne: 1s2 2s2 2p6
Octet rule
Goal of atoms Filled valence shellNoble gases
(Stable)
Mg2+: 1s2 2s2 2p6
+ 2e-
Mg: 1s2 2s2 2p6 3s2 Ne: 1s2 2s2 2p6
Octet rule
Goal of atoms Filled valence shellNoble gases
(Stable)
Mg2+: 1s2 2s2 2p6
+ 2e-
Mg: 1s2 2s2 2p6 3s2 Ne: 1s2 2s2 2p6
+ 2e-
O: 1s2 2s2 2p4 O2-: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6
Metals: lose 1, 2 or 3 e- Cation (Y+)
Nonmetals: gain 1, 2 or 3 e- Anion (X-)
Ions
Cation (Y+): Na+ Li+ Ca2+ Al3+
Anion (X-): Cl- F- O2-
Number of protons and neutrons in the nucleus remains unchanged.
Transition elements
1A 2A 3A 4A 5A 6A 7A 8A
Two problems of Octet rule
1. The octet rule cannot be used for transition and inner transition elements.
Fe2+ Fe3+ Cu1+ Cu2+
2. Ions of period 1 and 2 elements with charges greater than +2 are unstable.
C4+ C4- B3+C B
unstable unstable
Naming Monatomic Cations
International Union of Pure and Applied Chemistry (IUPAC) systematic names
Name of the metal + “ion”
H+ Hydrogen ionLi+ Lithium ion
Ca2+ Calcium ionAl3+ Aluminum ion
Cu1+ Copper(I) ionCu2+ Copper(II) ion
Fe2+ Iron(II) ionFe3+ Iron(III) ion
Hg+ Mercury(I) ionHg2+ Mercury(II) ion
Sn2+ Tin(II) ionSn4+ Tin(IV) ion
Naming Monatomic Cations
common name
Name of the metal +“-ous” smaller charge
“-ic” larger charge
Cu1+ Copper(I) ion Cuprous ionCu2+ Copper(II) ion Cupric ion
Fe2+ Iron(II) ion Ferrous ionFe3+ Iron(III) ion Ferric ion
Hg+ Mercury(I) ion Mercurous ionHg2+ Mercury(II) ion Mercuric ion
Sn2+ Tin(II) ion Stannous ionSn4+ Tin(IV) ion Stannic ion
Naming Monatomic Anions
Stem part of the name + “-ide”
Anion Stem name Anion name
F- fluor Fluoride ion
Cl- chlor Chloride ion
Br- brom Bromide ion
I- iod Iodide ion
O2- ox Oxide ion
S2- sulf Sulfide ion
P3- phosph Phosphide ion
N3- nitr Nitride ion
Naming Polyatomic Ions
Cation: NH4+ Ammonium
Anion:
OH- Hydroxide
NO2- Nitrite
NO3- Nitrate
SO32- Sulfite
SO42- Sulfate
HSO3- Hydrogen Sulfite
(bisulfite)
HSO4- Hydrogen sulfate
(bisulfate)
MnO4- Permanganate
CrO42- Chromate
Cr2O72- Dichromate
CO32- Carbonate
HCO3- Hydrogen Carbonate
(bicarbonate)
PO33- Phosphite
PO43- Phosphate
HPO42- Hydrogen phosphate
H2PO4- Dihydrogen phosphate
Ionic bonds
Metal-Nonmetal
Na: 1s2 2s2 2p6 3s1 Cl: 1s2 2s2 2p6 3s2 3p5
AnionCation
Na+: 1s2 2s2 2p6 Cl-: 1s2 2s2 2p6 3s2 3p6
Sodium (Na)
NaCl
Chlorine (Cl)
matter are neutral (uncharged):
total number of positive charges = total number of negative charges
Na+ Cl- NaCl
Ca2+ Cl- CaCl2
Al3+ S2- Al2S3
Ba2+ O2- Ba2O2 BaO
Molecule of NaCl Formula of NaCl
matter are neutral (uncharged):
total number of positive charges = total number of negative charges
Na+ NO3- NaNO3
Ca2+ CO32- Ca2(CO3)2 Ca(CO3)
Al3+ SO42- Al2(SO4)3
Mg2+ NO2- Mg(NO2)2
Naming Binary Ionic compounds
name of metal (cation) + name of anion
NaCl sodium chlorideCaO calcium oxide
Cu2O copper(I) oxide cuprous oxideCuO copper(II) oxide cupric oxide
Naming Polyatomic Ionic compounds
BaCO3 barium carbonate
Li2SO4 lithium sulfate Li2SO3 lithium sulfite
Covalent bonds
Nonmetal-NonmetalMetalloid-Nonmetal
Sharing ofvalence electrons
Lewis Dot Structure
H He Li CAl N Cl
H H Or H H
Or Cl H
Lewis Structure
HCl
Cl: 1s2 2s2 2p6 3s2 3p5
H: 1s1 He: 1s2
Ar: 1s2 2s2 2p6 3s2 3p6
HCl x
Shared pair of electrons(bonding pair of electrons)
Unshared pair of electrons(nonbonding pair of electrons) - (Lone pair)
Only valance electrons are involved in bonding (ionic and covalent bonds).
Electronegativity
A measure of an atom’s attraction for the electrons
Electronegativity Ionization energy
Covalent bonds
Nonpolar covalent bond: electrons are shared equally.
Polar covalent bond: electrons are shared unequally.
H Clδ+ δ-
Dipole
Electronegativity & bonds
Electronegativity Difference Between Bonded Atoms Type of Bond
Less than 0.5 Nonpolar Covalent
0.5 to 1.9 Polar Covalent
Greater than 1.9 Ionic
H H 2.1 – 2.1 = 0 Nonpolar covalent
N H 3.0 – 2.1 = 0.9 polar covalent
Na F 4.0 – 0.9 = 3.1 Ionic
Covalent compounds
H – C – H
–OCH2O H C H
OH – C – H
–O
H C H
O –
Correct
H C HH
HH – C – H
–H
–
H
CH4
H – N – H
–HNH3 H N H
H
H C C H
C – C
C2H4
H H
HH
H
H
H C C H
C = C
H H
HH
H
H
H C C H
H – C – C – H
C2H2H C C H
H – C C – H
Correct
Naming Binary Covalent compounds
Mono – Di – Tri – Tetra – Penta – Hexa – Hepta – Octa – Nona – Deca
1. Don’t use “mono” for the 1st element.
2. Drop the “a” when followed by a vowel.
NO2 nitrogen dioxide
N2O4 dinitrogen tetroxide
CCl4 carbon tetrachloride
S2O3 disulfur trioxide
prefix and full name of the first element in formula + prefix and the anion nameof the second element + “ide”
VSEPR Model
VSEPR: Valence-Shell Electron-Pair Repulsion method
Bond angle: angle between two atoms bonded to a central atom.
Each region of electron likes to be as far away as possible from the others.
Regions of electron density
Four regions of electron density around an atom:
Bond Angles in covalent molecules
Linear molecules
Trigonal planarmolecules
Tetrahedral molecules
2 regions
3 regions
4 regions
Unshared electron paires
H2OCH4 NH3
Polarity
1. Molecule has polar bonds.2. Its centers of δ+ and δ- lie at different places (sides).
O = C = O
δ- δ+ δ-
nonpolar molecule
H – C – H–H
–
H
δ+
δ+
δ+
δ+
δ-
C
=O
H Hδ+
δ-
polar molecule
N
HH H
δ-
δ+