CHEM 1125Q 1st Edition Lecture 8Outline of Last Lecture (Ch. 12)I. Liquids, Intermolecular Forces, Surface Tension, Viscosity, Vapor Pressure, and Clausius-Clapeyron EquationOutline of Current Lecture (Ch. 12)II. Properties of Liquids and SolidsA. Melting PointB. Vapor Pressure in SolidsIII. Amorphous and Crystalline SolidsA. AmorphousB. CrystallineIV. Types of CrystalsCurrent LectureII. Properties of Liquids and SolidsA. Melting Pointa. The melting point of a substance is the temperature at which individual particles obtain enough energy to break free from their fixed positionsb. Like boiling point, a substance’s melting point is a function of pressurei. When pressure increases, the melting point increasesii. However, water is an exception to this rule because it is actually more dense as a liquid than as a solidc. Every substance has Dispersion Forcesi. Ionic bonds have dipole-dipole forces, which are polarii. Any bond between a H and an F, N, or O is a hydrogen bond, which is also the strongest chemical bondiii. The melting point of a substance is related to the type of intermolecular forces presentB. Vapor Pressure in Solidsa. The vapor pressure in solids is typically low at room temperature, meaning that most solids do not sublime directly into their vapor formsb. Some examples of exceptions are moth balls and iceIII. Amorphous and Crystalline SolidsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.A. Amorphousa. An amorphous solid is one in which the molecules and atoms are in a random arrangement; no clear patternb. Amorphous solids lack a regular 3D arrangement in its molecules, and as a result they do not break into clean piecesi. One example of an amorphous solid is glassB. Crystallinea. The molecules and atoms in a crystalline solid do form a pattern and clear shape. This shape is typically rigid and in a long-range order where atoms occupy certain positionsb. Unit Celli. Crystalline solids are made up of unit cells, which are the smallest repeating structural units of the solidii. Nature tries to leave as little empty space as possible when packing together atomsiii. Unit cells can be categorized using 7 crystal systems, but for this course we will only focus on simple cubic, which is as its name states, a simple cube in shapeC. Crystal Packinga. Crystal packing is nature’s way of minimizing empty space by cramming as many atoms into a space as possibleb. The number of atoms surrounding an atom in a crystalline lattice is called its coordination number. This number indicates how closely packed together the atoms arec. There are 3 types of simple cubic structures:i. Simple (scc)1. The rarest of the 3 structures, the Simple Cubic has oneatom located at each corner, so that an eighth of each corner atom is actually inside of the unit cell2. A Simple Cubic has a total of 1 atom inside (8 corners x 1/8th an atom in each corner = 1)3. a = 2rii. Body-Centered (bcc)1. The second most common, the Body-Centered has one atom located at each corner as well as one atom in the center of the unit cell2. A Body-Centered has a total of 2 atoms inside (8 corners of 1/8th each like in the Simple plus the whole atom)3. a = 4r/√3iii. Face-Centered (fcc)1. The most common structure is the Face-Centered, which has one atom on each corner as well as one in the center of each of the cube’s 6 faces2. A Face-Centered has a total of 4 atoms inside (8 corners of 1/8th each like in the Simple plus 6 ½’s from the faces. 6 x ½ =3. 3+1=43. a = (√8)rIV. Types of CrystalsA. There are 4 main types of crystals based on the types of bonds found in them: Ionic, Covalent, Molecular, and Metallica. Ionici. In an ionic crystal, you can only define its unit cell based on one type of atom. For example, in a solid crystal of KCl, the shape is either scc, bcc, or fcc based on only one of those ionsb. Covalenti. Covalent crystals are often known as network covalent because their atoms are held together in an extensive 3D network made up entirely of covalent bondsc. Moleculari. In molecular crystals, the lattice points are occupied by molecules instead of single atoms, and the forces keeping the molecules together are Van der Waals forcesd. Metallici. In a metallic crystal, every lattice point contains an atom of thesame metal. The electrons in a metallic crystal are delocalized, meaning they are not associated with a single atom or