0 O 0 Lewis O o Dot ● Structures O O 0 Reading:Gray:(2-1),(2-7),(2-11)to(2-13) OGC:(3.5)to(3.8) 0 -1
Lewis Dot Structures Reading: Gray: (2-1), (2-7), (2-11) to (2-13) OGC: (3.5) to (3.8) V-1
Periodic Chemical Reactivity Reactions with hydrogen to form hydrides: LiH vs.HF (notice electronegativity difference) Reactions with fluorine: -HF VS.F2 ionic covalent Reactions with oxygen: -Li2O vs.CO2 vs.F2O Can we predict these structures? Can we understand their properties? Yes,we can!We use Lewis dot structures based on valence electrons. V-2
Periodic Chemical Reactivity Reactions with hydrogen to form hydrides: Reactions with fluorine: Reactions with oxygen: Can we predict these structures? Can we understand their properties? Yes, we can! We use Lewis dot structures based on valence electrons. HF vs. F2 LiH vs. HF (notice electronegativity difference) ionic covalent Li2O vs. CO2 vs. F2O V-2
Person of the Day ©1998H.MITCHELL G.N.Lewis V-3
G.N. Lewis Person of the Day V-3
GILBERT NEWTON LEWIS (1875-1946) "Heavy Water" Gilbert Newton Lewis,one of the most influential and admired scientists of the twentieth century,was a pioneer in both chemistry and physics.Born in Weymouth Landing,Massachusetts in 1875,Lewis was reading by the age of 3.He entered college at age 15,then transferred to Harvard University,where he earned a B.S.(1896)and Ph.D.(1899).His research concentrated on thermodynamics and valence theory (on the behavior of electrons when atoms combine).From this early work on valence,Lewis developed the concept of the covalent bond,and invented the "Lewis symbols"which are still used to describe ways in which atoms bond. Lewis taught at Harvard and MIT before becoming a Professor and Dean at the University of California at Berkeley,whose then languishing College of Chemistry he single-handedly transformed into one of the nation's best.Lewis became the mentor to 290 Ph.D.recipients and 20 Nobel Prize winners For example,he directed the experiments that resulted in the discovery of elements 93-106. In his own work,Lewis combined strict discipline in collecting and organizing data with innovative interpretation of the results.In the early 1930s,he became the first scientist to produce "heavy water," with double-weight hydrogen atoms,which was essential to early experiments in atomic energy.He also worked with Ernest Lawrence in the invention of the cyclotron and in early atom-smashing experiments. From the late 1930s to his death in 1946,Lewis focused on photochemistry.In fact,it was he who coined the term "photon." Gilbert Newton Lewis won numerous honors for his work,including the Society of Arts and Sciences Medal as "the outstanding chemist in America"(1930).He was nominated for the Nobel Prize in chemistry over 30 times,and still today,many scientists believe he well deserved it. V-4
GILBERT NEWTON LEWIS (1875-1946) "Heavy Water" Gilbert Newton Lewis, one of the most influential and admired scientists of the twentieth century, was a pioneer in both chemistry and physics. Born in Weymouth Landing, Massachusetts in 1875, Lewis was reading by the age of 3. He entered college at age 15, then transferred to Harvard University, where he earned a B.S. (1896) and Ph.D. (1899). His research concentrated on thermodynamics and valence theory (on the behavior of electrons when atoms combine). From this early work on valence, Lewis developed the concept of the covalent bond, and invented the "Lewis symbols"which are still used to describe ways in which atoms bond. Lewis taught at Harvard and MIT before becoming a Professor and Dean at the University of California at Berkeley, whose then languishing College of Chemistry he single-handedly transformed into one of the nation's best. Lewis became the mentor to 290 Ph.D. recipients and 20 Nobel Prize winners. For example, he directed the experiments that resulted in the discovery of elements 93-106. In his own work, Lewis combined strict discipline in collecting and organizing data with innovative interpretation of the results. In the early 1930s, he became the first scientist to produce "heavy water,” with double-weight hydrogen atoms, which was essential to early experiments in atomic energy. He also worked with Ernest Lawrence in the invention of the cyclotron and in early atom-smashing experiments. From the late 1930s to his death in 1946, Lewis focused on photochemistry. In fact, it was he who coined the term "photon." Gilbert Newton Lewis won numerous honors for his work, including the Society of Arts and Sciences Medal as "the outstanding chemist in America" (1930). He was nominated for the Nobel Prize in chemistry over 30 times, and still today, many scientists believe he well deserved it. V-4
Lewis Dot Structures How to:1)Write down configuration 2)Draw the structure (each valence e-gets a dot) Neon:(1s)2(2s)?(2p) valence level“n”is2 2+6=8 electrons on the valence level So Ne gets 8 dots: :Ne: Fluorine:(1s)2(2s)2(2p)5 What if we put 2 fluorines together? n=2 :F·+.F :F:F: 2+5=7 valence electrons for F Look！They both have8 So F gets 7 dots: electrons:so we predict F,is a stable molecule V-5
2 + 5 = 7 valence electrons for F So F gets 7 dots: Lewis Dot Structures How to: 1) Write down configuration 2) Draw the structure (each valence e– gets a dot) Neon: (1s)2 (2s)2 (2p)6 valence level “n” is 2 2 + 6 = 8 electrons on the valence level So Ne gets 8 dots: Ne Fluorine: (1s)2 (2s)2 (2p)5 n = 2 F What if we put 2 fluorines together? F + F F F Look! They both have 8 electrons: so we predict F2 is a stable molecule V-5