Organic Chemistry Lecturer (August 2008 – August 2013) Department of Chemistry University of Nebraska, Lincoln (UNL) Lincoln, Nebraska, USA Organic Chemistry Lecturer (July 2006 – July 2008) Department of Chemistry & Biochemistry Instructional Division University of California, Los Angeles (UCLA); Los Angeles, California, USA
University of Edinburgh Scotland, UK Post-doctoral Fellow University of Saskatchewan Saskatoon, Canada Ph.D. (Organic Chemistry) Indian Institute of Technology (IIT) Bombay, India M.Sc. (Organic Chemistry)
Missed Exams: In any class this large, there will be emergencies that cause students to miss exams. In the event of a verified emergency (medical or death in family), the student is to contact Professor Chatterjee by email and in person as soon as you get back. If, in my judgment, the excuse is valid I will substitute your final exam percentage for the test grade. If you miss more than one test, meet with me ASAP to discuss your options. I may require you to bring a Proof to document your absence. There will be no make up exams
Conceptual Questions are posed to the students Various scenarios are possible regarding • Students spend several minutes thinking about the question • Students Vote • Students discuss the question with their peers defending their answer and trying to reach consensus. • Students Vote again
•“Remember that the first vote reflects YOUR knowledge – there should be no talking before the first vote”. •“Remember that the second vote reflects the knowledge of YOU & YOUR PEERS. There should be lots of talking before the second vote.” •“This talking should be focused on scientific reasoning – the “why” you think a certain answer is correct – convince them that your answer is correct. Politely critiquing the reasoning of your peers or asking them to explain something more fully or in a different way is appropriate. You ultimately want to reach consensus.” • “You need to be sitting near a peer – you may need to get up and move!”
Goal & Objectives: Students will develop an understanding of 1. Bonding and three-dimensional structure of carbon based compounds. 2. Nomenclature of organic compounds 3. Organic chemical reactions and their mechanisms.
Wöhler is regarded as a pioneer in organic chemistry as a result of him (accidentally) synthesizing Urea in the Wöhler synthesis in 1828. This synthesis was a landmark in the history of science which disproved and undermined the Vital Forces which was believed for centuries, by showing that organic compounds could be synthesized from inorganic materials. Wohler also prepared urea, a constituent of urine, from ammonium cyanate NH4(NCO) in the laboratory without the help of a living cell. Wöhler was a co-discoverer of beryllium, silicon, and silicon nitride (Si3N4); hard ceramic. Silicon nitride bearings are used in the main engines of the NASA’s Space shuttles.
Friedrich Wöhler (31 July 1800 - 23 September 1882) was a German chemist, best-known for his synthesis of Urea, but also the first to isolate several chemical elements.
Carbon compounds are central to the structure of living organisms and therefore to the existence of life on Earth. We exist because of carbon compounds
Although carbon is the principal element in organic compounds, most also contain hydrogen, and many contain nitrogen, oxygen, phosphorus, sulfur, chlorine, or other compounds
a. Neutrons and protons are in the nucleus; electrons are in orbitals.
b. Neutrons and electrons are in the nucleus; protons are in orbitals.
c. Electrons and protons are in the nucleus; neutrons are in orbitals.
d. Electrons are in the nucleus; neutrons and protons are in orbitals.
2A. Isotopes
Although all the nuclei of all atoms of the same element will have the same number of protons, some atoms of the same element may have different masses because they have different numbers of neutrons. Such atoms are called isotopes
a. Atoms with the same number of neutrons, but a different number of electrons.
b. Atoms with the same number of protons, but a different number of electrons.
c. Atoms with the same number of protons, but a different number of neutrons.
d. Atoms with the same number of neutrons, but a different number of protons.
2B. Valence Electrons
Electrons that surround the nucleus exist in shells of increasing energy and at increasing distances from the nucleus. The most important shell, called the valence shell, is the outermost shell because the electrons of this shell are the ones that an atom uses in making chemical bonds with other atoms to form compounds
The number of electrons in the valence shell (called valence electrons) is equal to the group number of the atom
The aufbau principle states to fill the lowest energy orbitals first.
Hund’s rule states that when there are two or more orbitals of the same energy (degenerate), electrons will go into different orbitals rather than pairing up in the same orbital.
Electronic configuration of carbon
Recall: electron configuration of noble (inert) gas
Lewis structures show the connections between atoms in a molecule or ion using only the valence electrons of the atoms involved
For main group elements, the number of valence electrons a neutral atom brings to a Lewis structure is the same as its group number in the periodic table
If the structure we are drawing is a negative ion (an anion), we add one electron for each negative charge to the original count of valence electrons. If the structure is a positive ion (a cation), we subtract one electron for each positive charge
In drawing Lewis structures we try to give each atom the electron configuration of a noble gas
1.11 How many bonding pairs of electrons are in NH2OH?
a. One pair of electrons
b. Two pairs of electrons
c. Three pairs of electrons
d. Four pairs of electrons
1.13 How many nonbonding pairs of electrons are in NH2OH?
a. One pair of electrons
b. Two pairs of electrons
c. Three pairs of electrons
d. Four pairs of electrons
1.14 How many bonds (pairs of electrons) are in CH2=CH2?
a. Two bonds
b. Three bonds
c. Four bonds
d. Five bonds
e. Six bonds
Which type of bonding is present in the compound CH3Li?
a) Ionic bonding
b) Covalent bonding
c) Hydrogen bonding
d) Ionic and Covalent bonding
e) Ionic, Covalent, and Hydrogen bonding
H C C
H
H H
O O
H
H H C O
H
H
C O H
H
H C C
H
H O
O H
H
H
H C O
H
H
C O H
H
H
Which of the following is the Lewis structure for CH3CH2O2H?
b)
c) d)
e) None of these choices.
a)
4A. Exceptions to the Octet Rule
Elements in the 2nd row in the periodic table usually obey the Octet Rule (Li, Be, B, C, N, O, F) since they have one 2s and three 2p orbitals available for bonding
Elements in the 3rd row in the periodic table have d orbitals that can be used for bonding and may not obey the Octet Rule
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