CHEM 151 1st Edition Lecture 5- PEC Diagramso Some understanding about potential energy as well as number of configurations of the systemo Potential Energy (function of) Temperature, Distance, phase, attractive forces- Stronger the attraction of two particles together, the lower the potential energy can be Lower potential energy = stronger attractive forces Phase behavior is much more dependent on potential energy versus number of configurationso Number of Configurations Pressure (decrease pressure, more number of configurations allowed), randomness of a state is important o Lower potential energy, stronger attractive forces- Differences in particleso We assume the composition and the structure of the ‘particles’ are different o Difference in physical properties can be explained if we assume that the strength of the intermolecular forces among particles vary from substance to substance- Modeling Substanceso This is a typical chemical representation at the particulate level of the main components of ‘pure air’These 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.- 5 different particles in this diagram; the representation conveys the idea that we model air as a ‘mixture’- A system composed of two or more types of independent particles present in proportions that may vary from sample to sample- Individual particles of different substances are modeled as made of free or bonded atoms of different types- Moleculeo 2+ atoms that are bondedo They can be the same atom or different atoms- Classifying Substanceso The different components of a mixture can be separated by physical means (filtration, distillation)o Classify substances as elementary substances or compounds based on particlecomposition o Elementary substances: Nitrogen and Argon because there is only one type ofmolecule, Water is a compound- Elementary Substanceso The most simple substances in natureo Composed of identical particles made of free or bonded atoms of the same typeo Can be atomic or molecular- Chemical Compoundso Most substances in nature are chemical compoundso Composed of identical particles made of bonded atoms of two or more different typeso 2+ different atoms within the molecule- Molecular Compoundso There is a wide variety of molecular compounds in natureo This diversity of due to the possibility of having molecules with different compositions, sizes, and structureso Molecular formula: how much of each atom are present in that moleculeo Structural formula: arrangement of those atoms in space- Ionic Compoundso Chemical compounds made up of ions arranged in lattice networks (no molecules)o Typically a metal and non-metal- Temperature and kinetic energy are directly proportionalo Liquid phase (lower region of the diagram) has the strongest intermolecular forceso Potential energy depends on distance, temperature, phase, and attractive forces, so the gas phase has the highest (most positive) average potential energy per particle.o The particles with the highest average speed exist in the liquid phase Temperature is a measure of the average kinetic energy (average) If all of the atoms are at the same temperature and the same kinetic energy,  Kinetic Energy= ½(MxV)2- So if they have a higher velocity, they have a higher mass Liquid phase is composed of particles that have less mass, because they have less mass their temperature is going to be lowero Average kinetic energy is the lowest in both of the phases If they’re the same temperature, they have the same kinetic energyo In this diagram, carbon dioxide has the highest vapor pressure Depends on the amount of substance in the liquid phase compared tothe amount of substance in the gas phase If you have a greater proportion, then you have a greater vapor pressure  Ratio for gas to liquid in water is relatlively small, the ratio for gas to liquid in CO2 is higher, which means CO2 must have the higher vapor pressureUnit 1 Module 3- Distinguishing Substances; focusing mainly on mass- Indirect Measurementso Atoms and molecules have masses and sizes so small that can not be measured directly o Comparing the masses of samples of different substances with the same number (very large) of particles- Avogadro’s Lawo Equal volumes of different gases, at the same temperature and pressure, should contain the same number of