Chapter 3: Structure & Bonding PDF

Chapter 3: Structure & Bonding Topic 3.1: Ionic & Covalent Bonding Slides created by Dr. C. Booker Valence Electrons Only valence electrons participate in bonding H Cl Types of Bonds Typically, elements of – Low electronegativity – form ionic bonds – Moderate electronegativity...

Chapter 3: Structure & Bonding Topic 3.1: Ionic & Covalent Bonding Slides created by Dr. C. Booker Valence Electrons Only valence electrons participate in bonding H Cl Types of Bonds Typically, elements of – Low electronegativity – form ionic bonds – Moderate electronegativity – covalent – Higher electronegativity – covalent or ionic Ionic Bonding Complete transfer of electron(s) from one atom to another Occurs when electronegativity difference between atoms is greater than about 1.9 Crystal Lattices Formed by the strong electrostatic forces of ionic bonding Solid state and 3D High melting points for ionic compounds Image: The Difference Between Kosher Salt and Table Salt (todayifoundout.com) Covalent Bonds Electronegativity difference less than about 1.9 Electrons are shared between bonded atoms  Polar and Nonpolar Bonds Polar covalent bonds: unequal sharing of electron density – 0.5 < ΔEN 0 for molecule to exist (bond to form) – To exist: More electrons in bonding (stabilizing) MO than antibonding (destabilizing) MOs Paramagnetism & Diamagnetism Paramagnetic = attracted to a magnet Must have a nonzero net spin (∑ms ≠ 0), thus atom/compound must have one or more unpaired electrons Diamagnetic = not attracted to a magnet Zero net spin (∑ms ≠ 0), thus all electrons are paired Atoms and monoatomic ions: examine atomic orbitals Compounds: examine molecular orbitals MOs for Second Row, Homonuclear, Diatomic Molecules 2s similar to 1s orbital combination… Produce 2s and *2s MOs from 2p Atomic Orbitals This gets more interesting… Atom 1 Atom 2 MOs for Second Row, Homonuclear, Diatomic Molecules 2s similar to 1s orbital combination… Produce 2s and *2s MOs from 2p Atomic Orbitals This gets more interesting… Atom 1 Atom 2 Combination of 2px Orbitals On-axis overlap, symmetrical along axis, σ MOs from 2p Atomic Orbitals Only one set of p orbitals can form a σ bond Two sets of p orbitals can form bonds Atom 1 Atom 2 Combination of 2py Orbitals Sideways overlap, bond Combination of 2pz Orbitals Another sideways overlap, bond Relative Energies of Second-Period MOs (20) Paramagnetis m of Oxygen - YouTube