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117 Cards in this Set
- Front
- Back
Organic compounds are very complex and are only obtained from what? |
Living sources (vitalism) |
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What is vitalism? |
Belief that a "magic" vital force, present in plants and animals, is necessary for synthesis of organic compounds |
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Who observed that organic compounds are composed primarily of carbon and hydrogen? |
Antoine Laurent Lavoisier |
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What organic compound was synthesized from and inorganic compound in 1828? Who did it? |
Urea; Friedrich Wohler |
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Modern organic chemistry is the study of __________ compounds. |
carbon |
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The study and practice of O chem can be subdivided into three areas: |
1. Structure 2. Mechanism 3. Synthesis |
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Why is Carbon the main element studied in organic chem? |
Carbon forms a variety of strong covalent bonds to itself and other atoms (O, N, P, S , F, Cl, Br, I) Carbon can bond to itself in many different configurations, including chains, rings, and branched structures of varying size and complexity |
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What is the nucleus made up of? |
Protons and Neutrons |
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Protons have a ___________ charge |
positive |
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Neutrons are negatively charged. TRUE OR FALSE |
FALSE; no charge |
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Electrons are ___________ charged and are in __________. |
negatively; motion |
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Where does all the mass of an atom come from? |
The nucleus |
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Atomic number (Z) = ? |
# of protons in nucleus, # of electrons surrounding nucleus |
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Electrons surrounding the nucleus exist in what? |
Shells of increasing energy and at increasing distances from the nucleus |
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Define valence electrons |
Exist in the valence shell, and are the outermost electrons that are used in making chemical bonds |
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Electron cloud is about ________ times the diameter of its nucleus. |
10,000 |
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"An atom is most stable if its outer shell is either filled or contains 8 electrons, and it has no electrons of higher energy," What is this? |
Lewis bonding theory |
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Group # = # of ? |
Valence electrons |
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Define the octet rule |
An atom will give up, accept, or share electrons in order to achieve a filled outer shell o ran outer shell that contains 8 electrons |
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Define Electronegativity |
a measure of an atom's attraction for electrons that it shares in a chemical bond with another atom |
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How does electronegativity increase across the periodic table? |
Left to right Bottom to top |
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Electrons are completely transferred from one atom to another. What is this? |
Ionic bond |
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Define covalent bonds |
electrons are shared between two atoms |
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EN between bonded atoms >1.9 |
Ionic |
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EN between bonded atoms 0.5 to 1.9 |
Polar covalent |
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EN between bonded atoms <0.5 |
Nonpolar covalent |
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Atoms of widely different electronegativity (EN>2); usually a metal and a nonmetal, what is a result? |
Formation of ions, a cation(+) and an anion (-) |
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What are atoms held together by? |
Electrostatic attraction |
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Covalent bonding usually occurs between atoms of similar what? What are they usually? |
Electronegativity; non-metallic |
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Lewis dot structure vs Kekule drawing |
Lewis dot includes dots whereas Kekule includes lines 2 dots = 1 line |
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Define polar covalent |
Unequal sharing of electrons |
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How does an atom get a partial negative charge? |
The more electronegative atom gains a greater fraction of the shared electrons and acquires a partial negative charge. |
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How does an atom get a partial positive charge? |
The less electronegative atom has a smaller fraction of the shared electrons and acquires a partial positive charge |
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In CCl4, what happens? |
Each Cl has three lone pairs of electrons |
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Define lone pairs |
unshared pair of electrons; non-bonding pair of electrons |
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What is the HONC-1234 Rule? |
Hydrogen and Halogens make 1 bond Oxygen makes 2 bonds Nitrogen makes 3 bonds Carbon makes 4 bonds |
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Ethylene |
C2H4 |
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Double bond: |
two pairs of electrons |
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Triple bond: |
three pairs of electrons |
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Acetylene |
C2H2 |
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Hydrogen Cyanide |
HCN |
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CH4 |
Methane |
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What charges will you ONLY see in second row atoms? |
1, 0, and -1 |
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Formal charges help chemists do what? |
To keep track of the placement of electrons in molecules |
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How do you determine the formal charges? |
(Group #) - (# of nonbonding electrons) - 1/2(# shared electrons) |
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PRACTICE DOING FORMAL CHARGES |
PRACTICE |
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For line angle formulas, how should carbon atoms in a straight chain be drawn? |
In a zigzag formation |
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You have to write Hydrogens in line angle formula when they are bonded to heteroatoms. TRUE OR FALSE |
TRUE |
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When parentheses are used in condensed formulas, what does that mean? |
The part of the formula in parentheses is directly attached to the Carbon atom previously listed. |
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Get a piece of paper for practice: Convert following condensed formula to a line angle formula (CH3CH2)2CCHCH2CHOHCH3 |
YOU GOT THIS |
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What are the angle in a tetrahedral formation? |
109.5 degrees |
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What do lines mean when you are talking about the three dimensional shape of an organic molecule? |
Lines are in the plane of the paper |
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What do dashes mean when you are talking about the three dimensional shape of an organic molecule? |
The dashes mean the atoms are going back into the paper (away from you) |
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What do wedges mean when you are talking about the three dimensional shape of an organic molecule? |
The wedges mean the atoms are coming out of the paper (toward you) |
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Each ____________________ corresponds to a different energy state for an electron. |
wave function |
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What is the symbol for wave function? (What does it look like) |
A small pitch fork |
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Why do we discuss wave function in organic chemistry? |
Moving particles exhibit the properties of a wave |
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How can the relative probability of finding an electron in a given region of space be calculated? |
Wave function |
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What does the phase sign of a wave function indicate? |
Whether the solution is positive or negative when calculated for a give point in space relative to the nucleus |
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Each energy state is a sublevel where _____________ electrons can reside. |
one or two |
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When does constructive interference occur? |
When wave functions with the same phase sign interact. There is a reinforcing effect and the amplitude of the wave function increases. |
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When wave functions with opposite phase signs interact. What is this describing? What kind of effect does it have? |
Destructive interference; there is subtractive effect and the amplitude of the wave function goes to zero or changes sign |
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What is the symbol for wavelenth? Symbol for amplitude? |
Looks like an upside down v with a tail; amplitude = a |
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Study this image |
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A region of space where the probability of finding an electron is high. What is this defining? |
Orbital |
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Electrons are waves! So how do they exist? |
As 3-D standing waves (orbitals) |
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What are atomic orbitals? |
Unhybridized orbitals on an atom (s,p, d, f) |
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What is the difference between a hybird atomic orbital and a molecular orbital? |
A hybrid atomic is a combination of atomic orbitals from the same atom whereas a molecular orbital is comes from different atoms |
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What atomic orbitals are the most important in organic compounds? |
the s and p orbitals |
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What happens when you add orbitals together? What is the called? |
You always end up with the same # of orbitals you started with; conservation of orbitals |
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Individual wave functions (orbitals) combine to form ______________ and ____________________. |
Hybrid atomic orbitals and molecular orbitals |
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Name the types of hybrid atomic orbitals |
sp3, sp2, and sp |
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Name the types of molecular orbitals |
sigma, sigma*, pi, pi* |
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Describe s orbitals |
spherical, electrons held close the nucleus, one sign |
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Describe p orbitals |
two lobes with opposite signs, electrons further from nucleus. There are three degenerate (orbitals of equal energy) 2p orbitals that are higher in energy than the 2s orbital |
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The sign of the orbital indicates the charge. TRUE OR FALSE |
FALSE; it does not indicate the sign of the charge |
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Why is the Hund's Rule important? |
Partially filling orbitals as much as possible minimizes electrostatic repulsion between electrons |
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In molecular orbitals, what happens if the electrons get to be too close together? |
Nuclear repulsion |
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What is the Aufbau principle? |
Orbitals fill in order of increasing energy from lowest to highest |
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Only two electrons can occupy an orbital an their spins must be paired. What is this defining? |
Pauli exclusion principle |
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A _____________________ results when two orbitals of the same phase overlap. |
Bonding molecular orbital |
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What happens when two orbitals of opposite phase overlap? |
Antibonding molecular orbital |
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For bonding, where is the electron density centered? |
Between nuclei |
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For antibonding, what is generally between nuclei? |
Node |
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What is a node? |
Area of zero electron density |
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when there is a sigma bond, where is the electron density centered? |
Along the axis of the bond |
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What is the simplest sigma bond |
H2 |
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Which is more stable and lower in energy? less stable and higher in energy? |
Sigma (bonding) more stable and lower in energy Sigma* (antibonding) less stable and higher in energy |
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How many nodes are in a sigma bond between an s and a p orbital |
2 nodes |
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Pi bonding orbitals are cylindrically symmetrical and sigma bonding orbitals are not. TRUE OR FALSE. |
FALSE; Pi bonding orbitals are NOT cylindrically symmetrical whereas sigma bonding orbitals are. |
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Where is electron density located for a pi bond? |
Above and below the axis of the bond |
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What bonds constitute as pi bonds? |
Double and triple bonds |
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Orbitals must have the correct ___________ to overlap. |
symmetry |
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What types of orbitals do not overlap? Why? |
Orthogonal; because they cannot have bonding interaction |
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Di-substituted = ? (? degrees) |
linear; 180 degrees |
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Tri-substituted = ? (? degrees) |
trigonal planar; 120 degrees |
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Tetra-substituted = ? (? degrees) |
tetrahedral; 109 degrees |
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What is the Vesper theory? |
Getting all electrons as far apart as possible |
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What shape is this |
Tetrahedral |
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Shape? |
Trigonal planar |
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Shape? |
Linear |
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What theory did Linus Pauling come up with that combined VSEPR with quantum mechanics (orbitals)? |
HYBRIDIZATION |
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Atomic orbitals on the same atom combine to form hybrid atomic orbitals. WHY?
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Hybrid orbitals are more directional, so they have more effective bonding interactions |
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When looking at an sp3 hybridization (tetrahedral), what are the large orbitals vs the smaller orbitals? |
Large are bonding orbitals whereas small are antibonding orbitals |
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Electrons in pi bonds are always __________ in energy. |
higher |
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Sigma bonds are always made from what? |
Hybridized orbitals |
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Pi bonds involved ______________ p-orbitals |
unhybridized |
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How many pi bonds are in a triple bond? |
two |
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How many pi bonds are in a double bond? |
two |
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How do you calculate the number of hybrid orbitals? |
# of sigma bonds + # of lone pairs |
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Which orbital is the longest? |
sp orbital |
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Which orbital is the shortest? |
sp3 orbital |
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Sigma bonds rotate freely. TRUE OR FALSE |
TRUE |
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Pi bonds can rotate like sigma bonds. TRUE OR FALSE |
FALSE; cannot rotate |
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How do we represent electrons in motion? |
Curved arrow formalism (arrow pushing) |
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Double arrow: |
2 electrons moving |
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Fishhook arrow: |
1 electron moving |