Chemistry B11 Chapter 4 Chemical Bonds

Chemical Bonds Ionic bonds 2. Covalent bonds 3. Metallic bonds 4. Hydrogen bonds 5. Van der Waals forces

Chemical Bonds Ionic bonds 2. Covalent bonds

Review Shell 1 Maximum 2 electrons in valence shell Hydrogen and Helium Main-group elements 1A – 8A Other Shells Maximum 8 electrons in valence shell

Na: 1s2 2s2 2p6 3s1 Na+: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6 Octet rule Noble gases (Stable) Goal of atoms Filled valence shell Na+: 1s2 2s2 2p6 + e- Na: 1s2 2s2 2p6 3s1 Ne: 1s2 2s2 2p6 Ar: 1s2 2s2 2p6 3s2 3p6

Na: 1s2 2s2 2p6 3s1 Na+: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6 Octet rule Noble gases (Stable) Goal of atoms Filled valence shell Na+: 1s2 2s2 2p6 + e- Na: 1s2 2s2 2p6 3s1 Ne: 1s2 2s2 2p6 + e- Cl: 1s2 2s2 2p6 3s2 3p5 Cl-: 1s2 2s2 2p6 3s2 3p6 Ar: 1s2 2s2 2p6 3s2 3p6

Mg: 1s2 2s2 2p6 3s2 Mg2+: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6 Octet rule Noble gases (Stable) Goal of atoms Filled valence shell + 2e- Mg: 1s2 2s2 2p6 3s2 Mg2+: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6

Mg: 1s2 2s2 2p6 3s2 Mg2+: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6 O: 1s2 2s2 2p4 Octet rule Noble gases (Stable) Goal of atoms Filled valence shell + 2e- Mg: 1s2 2s2 2p6 3s2 Mg2+: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6 + 2e- O: 1s2 2s2 2p4 O2-: 1s2 2s2 2p6 Ne: 1s2 2s2 2p6

Cation (Y+): Na+ Li+ Ca2+ Al3+ Metals: lose 1, 2 or 3 e- Cation (Y+) Ions Nonmetals: gain 1, 2 or 3 e- Anion (X-) Number of protons and neutrons in the nucleus remains unchanged. Cation (Y+): Na+ Li+ Ca2+ Al3+ Anion (X-): Cl- F- O2-

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. C C4+ C4- B B3+ unstable unstable

International Union of Pure and Applied Chemistry (IUPAC) Naming Monatomic Cations International Union of Pure and Applied Chemistry (IUPAC) systematic names Name of the metal + “ion” H+ Hydrogen ion Li+ Lithium ion Ca2+ Calcium ion Al3+ Aluminum ion Cu1+ Copper(I) ion Cu2+ Copper(II) ion Fe2+ Iron(II) ion Fe3+ Iron(III) ion Hg+ Mercury(I) ion Hg2+ Mercury(II) ion Sn2+ Tin(II) ion Sn4+ Tin(IV) ion

Naming Monatomic Cations common name “-ous” smaller charge Name of the metal + “-ic” larger charge Cu1+ Copper(I) ion Cuprous ion Cu2+ Copper(II) ion Cupric ion Hg+ Mercury(I) ion Mercurous ion Hg2+ Mercury(II) ion Mercuric ion Fe2+ Iron(II) ion Ferrous ion Fe3+ Iron(III) ion Ferric ion Sn2+ Tin(II) ion Stannous ion Sn4+ 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 MnO4- Permanganate CrO42- Chromate Cr2O72- Dichromate CO32- Carbonate HCO3- Hydrogen Carbonate (bicarbonate) PO33- Phosphite PO43- Phosphate HPO42- Hydrogen phosphate H2PO4- Dihydrogen phosphate Anion: OH- Hydroxide NO2- Nitrite NO3- Nitrate SO32- Sulfite SO42- Sulfate HSO3- Hydrogen Sulfite (bisulfite) HSO4- Hydrogen sulfate (bisulfate)

Ionic bonds Metal-Nonmetal Cl: 1s2 2s2 2p6 3s2 3p5 Na: 1s2 2s2 2p6 3s1 Anion Cation Na+: 1s2 2s2 2p6 Cl-: 1s2 2s2 2p6 3s2 3p6 Donating receiving e-

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 chloride CaO calcium oxide Cu2O copper(I) oxide cuprous oxide CuO copper(II) oxide cupric oxide Naming Polyatomic Ionic compounds BaCO3 barium carbonate Li2SO4 lithium sulfate Li2SO3 lithium sulfite

Covalent bonds Nonmetal-Nonmetal Metalloid-Nonmetal Sharing of valence electrons

Lewis Dot Structure H He Li Al C N Cl H Or Cl Lewis Structure Cl: 1s2 2s2 2p6 3s2 3p5 H: 1s1 He: 1s2 Ar: 1s2 2s2 2p6 3s2 3p6

Unshared pair of electrons (nonbonding pair of electrons) - (Lone pair) Cl H x Shared pair of electrons (bonding pair of electrons) Only valance electrons are involved in bonding (ionic and covalent bonds).

Electronegativity Electronegativity Ionization energy 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 Cl δ+ δ- Dipole

Electronegativity Difference Between Bonded Atoms 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 H – CH4 H C H H – C – H – H H O O O O – CH2O – – H C H H – C – H H C H H – C – H Correct H H – NH3 H N H H – N – H

H H H H H C C H H C C H C2H4 H H H H C – C C = C H H H H Correct H C C H H C C H C2H2 H – C – C – H H – C C – H

of the second element + “ide” Naming Binary Covalent compounds Mono – Di – Tri – Tetra – Penta – Hexa – Hepta – Octa – Nona – Deca 1 2 3 4 5 6 7 8 9 10 Don’t use “mono” for the 1st element. Drop the “a” when followed by a vowel. prefix and full name of the first element in formula + prefix and the anion name of the second element + “ide” NO2 nitrogen dioxide N2O4 dinitrogen tetr(a)oxide CCl4 carbon tetrachloride S2O3 disulfur trioxide

VSEPR: Valence-Shell Electron-Pair Repulsion method VSEPR Model VSEPR: Valence-Shell Electron-Pair Repulsion method Bond angle: angle between two atoms bonded to a central atom. Each region of electrons likes to be as far away as possible from the others.

Bond Angles in covalent molecules Linear molecules 2 regions Trigonal planar molecules 3 regions Tetrahedral molecules 4 regions

Unshared electron paires CH4 NH3 H2O

Molecule has polar bonds. Polarity Molecule has polar bonds. Its centers of δ+ and δ- lie at different places (sides). H δ+ – δ- δ- δ+ δ+ δ+ H – C – H O = C = O – δ- H δ+ nonpolar molecule δ- O δ- = N C H H δ+ H H δ+ H polar molecule