CHEM 251 1st Edition Lecture 2 Outline of Last Lecture I. Origin of the Periodic TableII. Different Depictions of the Periodic TableIII. Periodic TrendsOutline of Current Lecture IV. Clicker QuestionV. Periodic Trends (Part 2)VI. Overview of Global Energy Current LectureIV. Clicker Questiona. Which reaction is more favorable?i. Na (g) + e- Na- (g)ii. Na (g) Na+ (g) + e- b. (i) is more favorable because it demonstrates electron affinity (usually releases energy)i. (ii) is an example of ionization energy, which is always endothermicV. Periodic Trendsa. Stabilityi. Elements above lead are unstableii. Unstable: decomposes by radioactive decayiii. Magic numbers (most stable nuclear configurations): 2, 8, 20, 28, 50, 82, 126iv. Even atomic numbers are more abundant, heavier elements are less abundantb. Atomic radiusi. Decreases going up a group, decreases going right across a periodc. Ionization energyi. Increases going up a group, increases going right across a period1. How hard is it to form a cation by pulling out an electron?2. Always a positive number3. Trend is stronger across a periodd. Electron affinityi. Increases going up a group, increases going right across a periodThese 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.1. How easy is it to form an anion by adding an electron?2. Can be positive or negativeVI. Overview of Global Energya. Energy: the ability to do something, universally conservedb. Where do we get energy?i. Shares of world primary energy: oil, coal, gas, hydro, nuclear, renewables c. Where DID we get our energy?i. Biomass (mostly wood-fired stoves)d.e. Current energy portfolioi. The fossil fuels (oil, gas, coal) are formed slowly over millions of years underground1. Recovered/extracted then combusted to produce energyii. Oil is the major provider of liquid fuels for use in transportationiii. Nuclear is in principle similar to fossil fuels: extraction followed by nuclearreaction.iv. Hydro is renewable, but limited by geographyf. Why alternative energy?i. Fossil fuels are a finite (albeit vast) resourceii. Burning fossil fuels for electricity & power results in CO2 emissionsiii. Energy sources come from all over the worldg. How can we change our energy portfolio?i. Utilize abundant, renewable energy sourcesii. Convert energy without producing CO2 emissionsiii. Take advantage of locally abundant
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