Unit 1 Introduction to Organic Chemistry

Question 1

Origin of Organic Chemistry

Answer 1

• Foundations date from mid-1700’s
• Compounds obtain from plants and animals
• Low-melting solids
• Hard to isolate, purify, and work with
• considered to have some vital force as they were from living sources
• though that could not be synthesized in lab

Question 2

In 1816 he found out that soap can e separated into several organic compounds which he termed fatty acids

Answer 2

Chevreul

Question 3

In 1828 he showed that it was possible to convert organic salt ammonium cyanate into organic substance urea

Answer 3

Wohler

Question 4

the study of carbon compounds, more than 50M known chemical compounds contain carbon

Answer 4

organic chemistry

Question 5

It is a group 4A element that can share 4 valence electrons and form 4 covalent bonds.
Able to bond with one another to form long chains and rings.
The only element that has the ability to form immense diversity of compounds

Answer 5

Carbon

Question 6

Bonding is almost covalent
May be gases, liquids, or solid with low melting points (less than 360’C)
Most are insoluble in water
Most are soluble in organic solvents such as diethyl ether, toluene, and dichloromethane
Aqueous solutions do not conduct electricity
Almost all burn
Reactions are usually slow

Answer 6

Organic Compound

Question 7

Most have ionic bonds
Most are solids with high melting points
Many are soluble in water
Almost all are insoluble in organic solvents 
Aqueous solutions conduct electricity
Very few burn
Reactions are often fast

Answer 7

Inorganic Compounds

Question 8

consist of Nucleus = proton+ neutron (contains essentially all the mass of the atom) and Electron

Answer 8

Atom

Question 9

diameter of an atom

Answer 9

2x10-10m or 200 picometers

Angstrom is 10-10m =100 pm

Question 10

number of protons or electrons in an atom’s nucleus

Answer 10

atomic number (Z)

Question 11

number of protons plus neutrons

Answer 11

mass number (A)

Question 12

weighted average mass in atomic mass units (amu) of an element’s naturally occurring isotope

Answer 12

atomic mass or atomic weigt

Question 13

atoms with the same atomic number but different mass numbers

Answer 13

Isotopes

Question 14

mathematical equation that describes the behavior of a specific electron in an atom

Answer 14

wave equation

Question 15

the solution of wave equation denoted by Greek letter psi

Answer 15

wave function or orbital

Question 16

4 kinds of orbitals:

Answer 16

s orbitals -spherical, nucleus at the center
p orbitals -dumbbell-shaped, nucleus at the middle (px, py, or pz)
d orbitals -elongated dumbbell-shaped, nucleus at the center
f orbitals

Question 17

atomic structue - orbitals:

Answer 17

orbitals of an atom are organized into different electron shells
centered around the nucleus in shells of increasing size and energy
different shells contain different numbers and kinds ff orbitals
each orbital can be occupied by 2 electrons

Question 18

atomic structure: electron configuration:

Answer 18

ground-state electron configuration: listing of orbitals occupied by an atom’s electrons
called lowest-energy arrangement

Question 19

lowest energy orbitals fill first in order of 1s-2s-2p-3s-3p-4s-3d

Answer 19

Aufbau principle

Question 20

electrons act as if they were spinning around an axis
spin can have only 2 orientations up and down
only 2 electrons can occupy an orbital, and they must be of opposite spin

Answer 20

Pauli exclusion principle

Question 21

if two or more empty orbitals of equal energy are available, electrons occupy each with parallel spins until all orbitals have one electron

Answer 21

Hund’s rule

Question 22

in 1858 they independently proposed that, in all organic compounds, carbon is tetravalent- they always form four bonds when it joins other elements

Answer 22

August Kekule an Archibald Couper

Question 23

in 1874 they proposed that four bonds of Carbon are not oriented randomly but have specific directions

Answer 23

Jacobus van’t Hoff and Joseph Le Bel

Question 24

atoms form _____ because the resulting compound is more stable than separate atoms

Answer 24

bonds

Question 25

atom's outermost shell

Answer 25

valence shell

Question 26

ions held together by a electrostatic attraction formed as a result of electron transfers

Answer 26

Ionic bonds

Question 27

formed by sharing of electrons e.g CH4, methane

Answer 27

Covalent bond

Question 28

electron-dot structures that represents valence shell electrons of an atom as dots

Answer 28

Lewis structure

Question 29

line-bond structures that indicates two-electron covalent bond as a line drawn between atoms

Answer 29

Kekule structures

Question 30

has five valence electrons (2s2 2p3) forming three bonds

Answer 30

Nitrogen

Question 31

valence electron not use in bonding

Answer 31

Lone pair

Question 32

a covalent bond forms when 2 atoms approach each other closely and singly occupied orbital on one atom overlap a singly occupied orbital on the other atom H-H bond results from the overlap of 2 singly occupied hydrogen 1s orbitals H-H bond is cylindrically symmetrical, sigma (0) bond

Answer 32

Valence bond theory

Question 33

ideal distance between nuclei that leads to maximum stability too close= they repel too far= bonding is weak

Answer 33

bond length

Question 34

occurs when atoms are ready to form bonds | to predict the bond angles in these molecules we use the Valence-Shell Electron-Pair (VSPER) Model

Answer 34

Hybridization

Question 35

the angle between two atoms bonded to a central form

Answer 35

bond angle

Question 36

3 hybrid orbitals:

Answer 36

sp3 sp2 sp

Question 37

``` he proposed the s orbital and three p orbitals an combine, or hybridize, to form four equivalent atomic orbitals with tetrahedral orientation 109.5 degree angle Single Bond e.g methane CH4 bond angle form between 2 adjacent bonds ```

Answer 37

Linus Pauling

Question 38

the simplest molecule containing carbon-carbon bond

Answer 38

Ethane C2H6

Question 39

___orbitals are in a plane with an angle of 120 degrees from each other exhibits double bond trigonal planar geometry head-on overlap gives what is called a sigma (0) bond sideways overlap gives a pi bond

Answer 39

sp2

Question 40

H atoms forms s bonds with four sp2 orbitals H-C-H and H-C-C form bond angles of about 120 degrees C-C bond in ethylene is shorter and stronger than single bond in ethane

Answer 40

Ethylene C2H4

Question 41

____ can form a triple bond sharing six electrons Carbon 2s orbital hybridizes with a single p orbital giving 2 sp hybrids sp orbitals are linear geometry, 180 degrees apart on axis

Answer 41

Carbon

Question 42

sharing of six electrons form C-C triple bond 2 sp orbitals from s bonds with hydrogens shortest and strongest carbon-carbon bond

Answer 42

Acetylene C2H2

Question 43

when it is bound to 2 other atoms with the help of 2 double bonds ore one single and one triple bond. Molecules have linear arrangement of the atoms with a bond angle of 180 degree

Answer 43

sp Hybridization

Question 44

bonding takes place between 1 s-orbital with 2 p orbitals. Formation of 2 single bonds and one double bond between three atoms. The hybrid orbitals are placed in a triangular arrangement with 120 degree angle between bonds

Answer 44

sp2 Hybridization

Question 45

molecular orbital that is lower in energy than the atomic orbitals from which it is formed

Answer 45

Bonding MO

Question 46

molecular orbital that is higher in energy than the atomic orbitals from which it is formed

Answer 46

Antibonding MO

Question 47

bonds that are neither fully ionic nor fully covalent but are somewhere between the two extremes

Answer 47

polar covalent bonds

Question 48

intrinsic ability of an atom to attract shared electrons in a covalent bond

Answer 48

electronegativity

Question 49

molecule structures that cannot be shown with a single representation such structure are delocalized are are represented by_____

Answer 49

resonance form

Question 50

structure with resonance forms, that does not alternate between the forms e.g Benzene resonance leads to stability

Answer 50

resonance hybrids

Question 51

_______is sstabel because it is symmetrical

Answer 51

Allylic Carbocations