Week 2 Textbook Reading

Question 1

condensed structure

Answer 1

Used only for small molecules or portions of molecules because it is difficult to show molecules of any size bigger using this style
Carbon atoms that carry 3 bonds can be negative or positive, depending on whether or not they have a lone pair

Question 2

line structure

Answer 2

Used to depict the shape of a molecule, effectively reducing the clutter

Question 3

key structural features of organic molecules

Answer 3

The key structural features of organic molecules include the hydrocarbon, the functional groups and any substituents

Question 4

The chemical rxns that molecules undergo happen primarily through the …

Answer 4

functional groups on the molecule

Question 5

alkanes

Answer 5

Hydrocarbons in which all the carbons are sp^3 hybridized are called alkanes

Question 6

Substituents

Answer 6

Substituents are a particular atom or group of atoms that replace a hydrogen atom in an organic molecule

Question 7

saturated molecules

Answer 7

Molecules and parts of molecules that have only single bonds connecting the atoms are known as saturated molecules

Question 8

unsaturated molecules

Answer 8

Organic molecules that have pi bonds are unsaturated molecules

Question 9

R group

Answer 9

Functional groups in a line structure are referred to as group “R”, in this case, R refers to remainder or residue
They can be identified by 2 main features: pi bonds and heteroatoms

Question 10

alkenes

Answer 10

Alkenes (C=C, sp2 hybridized)

Question 11

alkynes

Answer 11

Alkynes (C≡C, sp hybridized)

Question 12

Aromatics

Answer 12

(special ring structures with alternating patterns of single and double bonds

Question 13

pi bonds

Answer 13

Alkenes, alkynes and aromatics have one or more pi bonds
These bonds are weaker and more reactive than hydrocarbon sigma bonds; therefore, structures that have pi electrons (pi bonds) will be functional
In line structure diagrams, pi bonds always appear as parallel bond lines

Question 14

hetero atoms

Answer 14

Any atoms other than carbon or hydrogen
Have one or more non-bonded pairs of electrons (lone pairs) that can participate in reactions
A pi bond directly connected or adjacent to a heteroatom should be considered as part of a single functional group involving the bond and the heteroatom

Question 15

how are intermolecular forces created

Answer 15

The distribution of electrons generates intermolecular forces between organic molecules
Such forces are much weaker than those of covalent bonds within organic molecules
Intermolecular forces result from charge interactions; opposite charges attract and like charges repel

Question 16

electrostatics

Answer 16

One type of intermolecular force between organic molecules is electrostatics
Electrostatic interactions take place where organic functional groups have a full formal charge, creating strong attractive forces between molecules
These interactions represent the strongest type of intermolecular force and result in ionic structures

Question 17

dipole-dipole interaction

Answer 17

Dipole-dipole interaction results from attractive forces between the poles of the functional groups on one molecule and the opposite poles of the groups on the neighbouring molecules
Some functional groups have no charge but carry a permanent dipole due to the electronegativity difference between the atoms in the group
Dipoles are possible whenever there is a significant electronegativity difference between atoms in a functional group, and the compounds resulting from such interactions are said to be polar

Question 18

hydrogen bonding

Answer 18

Special kind of dipole-dipole interaction that is possible for groups with very electronegative atoms bonded to hydrogen atoms
This interaction is very important for OH and NH groups
The electronegativity difference between the heteroatoms (O or N) and the hydrogen is large and generates a very strong dipole
This dipole involves the lone pairs of the heteroatom forming a dipole-dipole interaction with the hydrogen of a nearby similar group

Question 19

hydrogen bond donor

Answer 19

When 2 functional groups participate in hydrogen bonding, the group that provides the hydrogen atom is the hydrogen bond donor

Question 20

hydrogen bond acceptor

Answer 20

The group that provides a lone pair of electrons to form the hydrogen bond is called the hydrogen bond acceptor

Question 21

polar protic donors

Answer 21

Polar protic donors are those solvents capable of acting as hydrogen bond donors

Question 22

london forces

Answer 22

n forces
London forces are attractive interactions that exist between all molecules in close proximity to each other, regardless of whether or not they engage in other intermolecular interactions
They are the result of small temporary dipoles induced in each molecule by the other

Question 23

Since hydrocarbons do not have any kind of permanent dipole, they are…

Answer 23

non-polar
-Weakest intermolecular force

Question 24

boiling and melting point

Answer 24

The melting point or boiling point of a substance provides a measure of the amount of energy required to separate molecules
Substances with strong intermolecular forces require more energy to break apart the molecules, so they have higher boiling points and melting points.

Question 25

what causes higher BP and MP

Answer 25

The more functional groups, the more polar interactions are possible, which results in higher MP and BP

Question 26

solvent

Answer 26

Solvent: a liquid in which compounds may be dissolved

Question 27

solvent

Answer 27

Solvent: a liquid in which compounds may be dissolved

Question 28

solute

Answer 28

the material that's dissolved in the solvent

Question 29

polar protic solvents

Answer 29

Polar protic solvents, usually the most polar of the solvents, can act as hydrogen bond donors and are often miscible with water. In fact, water is a polar protic solvent.

Question 30

polar aprotic solvents

Answer 30

Polar aprotic solvents have strong dipoles, and most can act as hydrogen bond acceptors, which makes many of them highly water-soluble.

Question 31

non-polar solvents

Answer 31

Non-polar solvents have their molecules held together primarily by London forces.

Question 32

hydrophobic

Answer 32

Very non-polar compounds such as hydrocarbons do not dissolve in water, and these molecules are hydrophobic In this situation, the attractive force between polar water and the temporary dipole in a nonpolar molecule is too weak to replace the strong hydrogen bonds between water molecules

Question 33

hydrophilic

Answer 33

Hydrophilic molecule is polar enough to form favourable intermolecular interactions, including hydrogen bonding with water

Question 34

alkane

Answer 34

Simple alkanes Root name describes the longest chain (octane) Location number of the branch is placed, separated by a hyphen, before the name of the branch More than 2 branches → alphabetical order Cyclic alkanes The prefix cyclo is added before the part of the name that describes the cyclic chain

Question 35

alkene

Answer 35

Hydrocarbons that have π bonds require a particular suffix to identify their functional group The suffix ene indicates a molecule has a carbon-carbon double bond, so a molecule with at least one carbon-carbon double bond To properly name an alkene, first indicate the position of the double bond by numbering the carbon chain starting at the end closest to the double bond, then insert the number of the first carbon of the double bond between the root name and the suffix Compounds that have more than one double bond require a descriptor that indicates the number of double bonds in the molecule These descriptors are the same as the ones used to indicate the number of identical substituents (di, tri, tetra, etc.) The descriptor is added just before the ene of the suffix. E.g. deca-2,6-diene

Question 36

alkyne

Answer 36

Compounds that have triple bonds are called alkynes. The suffix yne indicates the functional group is an alkyne. The naming of alkynes follows the same process as the naming of alkenes

Question 37

If there are both double and triple bonds in a molecule...

Answer 37

the alkyne has higher priority; therefore, it is listed last and chain numbering is based on the alkyne Such a molecule is an enyne

Question 38

functional groups

Answer 38

Functional groups other than alkenes or alkynes are distinguished either by a prefix or suffix If a molecule has only one such functional group, the suffix in its name corresponds to the functional group, and the parent chain is the one to which the group is attached

Question 39

resonance forms

Answer 39

A straight double-headed arrow is used to separate and indicate that such structures are resonance forms of the same functional group

Question 40

delocalized

Answer 40

The electrons in such structures are said to be delocalized Rather than forming a bond between 2 atoms, some of the electrons in these groups are shared by multiple atoms and participate in holding all of those atoms together

Question 41

effect of delocalization

Answer 41

Functional groups that participate in resonance gain stability because some of the electrons in the structure are shared between several atoms This delocalization reduces electron repulsion and alters bond strength

Question 42

For a functional group to have delocalized electrons (described by resonance), at least one of the following structural features must be present:

Answer 42

A pi bond made up of atoms with different electronegativities A pi bond directly beside at least one of the following features: Paired or unpaired electrons Atoms with incomplete octets Other pi bonds Charged atoms lacking octets or carrying lone pairs An atom with an incomplete octet adjacent to an atom with a pair of non-bonding electrons

Question 43

carbonyl groups

Answer 43

composed of a carbon and an oxygen connected by a double bond Because the oxygen and carbon have different electronegativities, they do not share the electrons in the pi bond equally → described by resonance Breaking the pi bond of the group gives another resonance form, which’s a significant contributor to the structure of the group

Question 44

drawing resonance structures

Answer 44

To draw resonance structures for molecules that have an existing formal charge, use the charge as a starting point for resonance analysis -A positive charge attracts electrons and tends to “pull” adjacent lone pairs and pi bond electrons toward it -A negative charge repels electrons and “push” them into adjacent pi bonds, positive charges and atoms lacking full octets -Not all negatively charged atoms carry lone pairs -Negatively charged atoms without lone pairs do not participate in resonance

Question 45

evaluating resonance form contributions

Answer 45

The relative contributions of resonance forms to the overall structure of the functional group or molecule are not always equal In drawings of chemical structures and rxns, functional groups are normally represented by the “best” (highest contributing) resonance forms In general, contributing resonance forms have the following characteristics: The most atoms with full octets The smallest number of formal charges Negative formal charges located on the most electronegative atoms Positive formal charges located on the most electropositive atoms Like charges separated by the maximum distance possible Opposite charges as close together as possible

Question 46

Significant and insignificant structures

Answer 46

Insignificant resonance forms can occur when electrons from a breaking bond pi bond flow to an atom with inappropriate electronegativity An insignificant resonance form can occur when breaking the pi bond and pushing the electrons onto the less electronegative carbon atom, resulting in an insignificant resonance form

Question 47

aromaticity

Answer 47

There’s a continuous band of pi electrons that circulates in a ring structure, creating a very strong connection between the atoms that make up the ring