Chapter 3 Atoms First.docx - Chemistry: Atoms First Chapter...

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Chemistry: Atoms FirstChapter 3: Quantum Theory and the Electronic Structure of Atoms3.1 Energy and Energy ChangesEnergyis the capacity to do work or transfer heatForms of EnergyAll forms of energy are either kinetic or potentialkineticenergy is the energy that results from motion-EK= 1/2mu2oM is the mass of the object and u is its velocity-One form of kinetic energy is thermalenergy – energy associated with the randommotions of atoms and moleculesoWe can monitor changes in thermal energy by measuring temperaturechangesPotentialenergy is the energy possessed by an object by virtue of its position: two formof potential energy of greatest interest to chemists are chemical and electrostatic-Chemicalenergy is potential energy stored within the structural units of chemicalsubstances – the amount of chemical energy in a sample of matter depends on thetypes of arrangements of atoms in the structural units that make up the sample-Electrostaticenergy is potential energy that results from the interaction of chargedparticles – opposite charged particles attract each other, and particles of like chargesrepel each other. The magnitude of the resulting electrostatic potential energy isproportional to the product of the two charges (Q1and Q2) divided by the distancebetween themIf the charges Q1and Q2are opposite (one positive and one negative), the result is anegative value for Eel, which indicates attraction. Like charges result in a positivevalue for Eel, indicating repulsionKinetic and potential energy are interconvertible – one form can be converted to theother but total amount of energy in the universe is constant – energy can be neithercreated nor destroyed-When energy of one form disappears, the same amount of energy must appear inanother form or forms – law of conversation of energyUnits of EnergyThe SI unit of energy is the joule (J) – amount of energy exerted when a force of 1newton (N) is applied over a distance of 1 meter-Magnitude of a joule is so small – often express large amounts of energy using theunit kilojoule (kJ)

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Term
Fall
Professor
Dr. Conticello

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