Types of Solids- Ionic solids: made of cations and anions; held together by attractive forces between the two- Metallic solids: metal; metallic bond (holds everything together in solid state)- Molecular solids: compounds held by covalent bonds; molecules held together by intermolecularforceso Stronger: crystalline Weaker: amorphous- Covalent networks: atoms connected through chain of covalent bonds to every other atom in moleculeo Ex: diamondPhysical Characteristics- As interactions get stronger in solid, we have much higher melting pointso Have to overcome intermolecular forces- Ex: Water vs. NaCl vs. cast iron vs. diamond (melting points); diamond (covalent bonds)  NaCl (ionic interactions)  cast iron (metal)  water (H bond is weakest)o Easy to melt water (low melting point)o Cast iron and NaCl: iron has lower melting pointo Diamond: extremely high melting point (to break ***covalent bonds***)- Ionic compounds fracture under stress- Covalent structure: needs a lot more force to cut it- Metals: malleable (don’t break, they bend and stretch to change shape)- Forces are not localized; change shape and directions of intermolecular forceso Can’t do that in covalent or ionic solids (held rigid in place)o In metal: move positions of atoms- Molecular solids: brittle, soft when compared to other solidso Ex: ice (not soft but softER)Molecular Orbital (MO) Theory- Ch. 9- Highest occupied molecular orbital (the HOMO)- Lowest occupied molecular orbital (the LOMO)- Energy increases as it goes up in orbitals- Makes metallic bonds so much easier to deal with- Blending of atomic orbitals to form molecular orbitals- Lowest energy state to highest: fill MOs in the same way as electron configuration- Bonding orbitals vs. antibonding orbitals- 0 K : absolute zero (no energy left behind; all motion has pretty much stopped-except electrons)Clicker: This theory of metallic bonding is calledA Music theory D Band theoryB MO theory E Gap theoryC Hole theoryUnoccupied p orbitals (ex: lithium & beryllium): in others, will form molecular orbitals that we have to worry aboutMetalsClicker: Could a metal at 0 K (absolute zero) conduct electricity?A Yes B No- Fermi: all electrons are below Fermi level so they can’t move- If you put in an electron, you add energy- Not a right answer to this questionHow does a hole move in a metal?- Move an electron nearby into the hole; creating a new hole- Positively charged hole attracted by negative electron- Holes and electrons move in opposite directionsSemiconductors and Insulators- Band gap between valence band (filled levels) and conduction band (empty levels)- Positive hole below the Fermi level  electron promoted to conduction bando Put energy in to excite electrons up into that band (if gap is small enough)  conduct electricity- Insulators: large band gaps; don’t allow electrons into conduction band- How computers work; binary concept; electrode is either on or off (conduct electricity or not)o Can’t do it with metal because there is no band gap to turn it off - Extrinsic: “doped” in some quantity of another elemento Acceptor level: provides constant supply of holes Add element that has less electrons (Group 3A) Holes from lost electrons P-typeo Donor Level: provides constant supply of electrons Add element that has more electrons (Group 5A) N-typeo Both in the gap between Conduction and Valence BandsClicker: Extrinsic semiconductors with an acceptor level are referred to as:A n-type B h-type C a-type D p-typeLattice Energy- Ex: NaCl Na cation being attracted to 6 Cl anions (nearest neighbors); repulsion to some Na anions around it too- Decreasing interactions as we keep going out- Sum of all of these attractive and repulsive forces = lattice energy- Reporting number: lattice energy is negative (put in that amount of energy to break lattice)Clicker: Rank the following compounds from weakest to strongest lattice energiesA sodium chloride B Rubidium chloride C Magnesium oxide D Magnesium sulfide(+1, -1) +1, -1 +2, -2 +2,-2)(-788.5 -687 -3826 -3406)BADC - the more negative the number, the stronger the lattice energy- Coulombic in nature: attraction increases as we increase the charges; shorter the distance, the interaction increases- C & D have to have higher lattice energies - Oxide is smaller, so D has lower lattice energy than sulfide- Na is smaller, so A has lower lattice energy than rubidium- Look at charges first; then look at the sizes of the elementsClicker: The Born-Haber Cycle is based onA Hess’s Law B Boyle’s Law C Charles’ LawD Pauli Exclusion Principle E Aufbau Principle- Hess’s law: stated that the change in energy btwn some initial state and some final state is independent from the pathway used to get from the initial state to the final stateo Ex: 2 start on 4th floor; one use stairs to go to 3rd floor; one goes up to 6th, down to 1st, up to 5th, down to 2nd, and up to 3rd; change of state is still -1.o “Where did you start and where did you finish?” is what is important- Born-Haber: some cation and anion (MX) that starts as solid change them to some state where there are no more attractive and repulsive forces; change them to gas phaseo Each of the ions will be independent (b/c they are so far apart)- Have to look at series of reactions that you can measureo Heats of formation of metal and ions, first ionization energies of vaporsCalculate the molar enthalpy of formation of solid sodium iodide.Cl (g) + e-  Cl- (g) -349 kJ/molNa (g)  Na+ (g) + e- 496 kJ/mol∆f Cl (g) 121.3 kJ/molNa (g) 107.3 kJ/molNaCl (s) -411.12 kJ/molNaCl (s)  Na+ (g) + Cl- (g)½ (2NaCl (s)  2Na+ (g) + Cl2 (g))Na (s)  Na (g)Cl (g) + e-  Cl- (g)Na (g)  Na+ (g) + e- NaCl (s)  Cl- (g) + Na+