Chapter 1 Flashcards
In science, the term organic means
anything that is or has been alive
Organic chemistry is
a branch of chemistry which involves the study of the chemical compounds consisting primarily of carbon and hydrogen
The key to they variety of organic compounds that exist lies in the unique bonding abilities of the carbon atom, which are…
1) Carbon atoms can form strong single, double, & triple bonds in various length –> with other atoms like oxygen & nitrogen, you can’t make large molecules cuz then they become unstable. Ex. 3 oxygen=ozone
2) Carbon atoms can form linear or branched molecules
3) Carbon atoms may be arranged in rings to form a variety of structures with different shapes –> u can have multiple rings attached to each other as well
4) Carbons can form very large and complex compounds
Why can’t Oxygen or Nitrogen form compounds like carbon?
-with oxygen & nitrogen, you can only make 1 double or triple bond and ur done
- u can’t make a lengthy, large molecule –> bigger molecules of Oxygen & Nitrogen are also unstable
–> Ex, 3 oxygen=ozone
Lewis Structure
only show the valence electrons
Nomenclature rules for ALKANES
1) The parent must be the longest C-C chain, C1 must be closest to the branches
2) The branches must be listed in alphabetical order, with the SMALLEST POSSIBLE # for the branches
3) When the branches are identical, use the prefix “di, tri, tetra…” to indicate duplicity
4) Between 2 # there must be a comma
5) Between a # and a letter, there must be a dash (-)
-rmr when determining alphabetical order, don’t include prefix
- carbon #1 is end closest to the branch
- if branches are at same distances no matter where you start, C gets greater priority over halogen
- rmr we want the smallest branch #s
Name of Branches
-Br= bromo
-Cl= chloro
-F= fluoro
-I= iodo
-OH= hydroxy
-NH2= amino
-NO2= nitro
Nomenclature rules for ALKENES
there must be at least one double CC bond
- The parent must contain the double bond(s), even if it’s not the longest possible chain
- C1 must be closer to the double bond, even if C1 is further from the branches
- In a ring, the CC double bond must be the first bond. It’s location can be skipped if there’s only 1 double bond
-if there is a branch on one end of the double bond, make that branch #1
- between the hept - 2 - ene, u can’t have a –1) consonant, consonant 2) vowel, vowel
ALKYNE
there must be at least 1 CC triple bond
Isomers are
molecules that have the same molecular formula but their atoms are in different arrangements
Constitutional Isomers
- molecules that have the same molecular formula, but different atom-to-atom connection
-Example: A-B-C, A-C-B, B-A-C
rmr Linear Alkane formula = CnH2n+2
- Double bond: lose 2H
- Ring: lose 2H
- Triple bond: lose 4H
Stereoisomers
- molecules that have the same molecular formula and atom-to-atom connection but differ in 3D orientations of their in space
- Cis-isomer: larger groups are on the same sides of the double bond
- Trans-isomer: larger groups are one the opposite sides of the double bond
Aromatics
- special group of cyclic hydrocarbons. They appear to have alternating single & double bonds
- The electrons are equally shared around the ring - there are no single or double bonds in benzene. Instead, we have 6 identical 1.5 bonds (halfway between single & double bonds)
Nomenclature
The benzene is the parent unless:
- the linear chain contains a double bond, a triple bond or have more than 6 carbons, then the linear chain is the parent & the benzene ring is a branch called “phenyl”
Combustion Reactions
- All hydrocarbons burn rapidly with O2 to produce CO2, H2O, & a large amount of energy (heat & light)
- These reactions are not spontaneous & must be started by a spark, heat or light
- Combustion of fossil fuels is a major source of useful energy for humans. –> Ex, natural gas, gasoline, kerosene, candles, wax, jet fuel
Complete Combustion Reactions
Occurs when the oxygen supply is unlimited (excess reagent)
- Products: CO2 + H2O+ lots of energy
- Ideal way to burn fuel cuz it releases the most energy from the fuel molecules
- Produces the cleanest & hottest flames (blue)
Incomplete Combustion Reactions
Occurs when oxygen supply is limited (limiting reagent) –> like in an enclosed space
- Products: CO2, H2O, CO, C, & less energy
- Flames are often sooty (like the black fume that comes out of cars), yellow, & cooler
- excess CO can cause headaches & breathing difficulty –> CO binds to hemoglobin in out blood & does not allow blood to carry O2 as easily. –> increased levels of CO in blood can cause death
Why don’t we cook with gasoline (C8H18)
1) bad smell
2) u would need a lot of oxygen for a complete combustion reaction
Addition Reaction of Alkenes
- hydrocarbons that contain only single CC bonds (alkanes) are called SATURATED and are not very reactive
- UNSATURATED hydrocarbons contain double & triple bonds & r much more reactive
- Alkenes & alkynes undergo addition reactions in which atoms are added to a double or triple bond. End product=alkanes
Addition Reaction of Alkenes: Markovnikov’s Rule
For addition of HX to alkenes, the H atom adds to the Carbon with the most atoms to give the major product
- treat H like money –> THE RICH GETS RICHER
Elimination Reactions
- opposite of addition reaction –> H & X are removed to form a double bond between 2 carbon atoms
alkane –> alkene - first identify the x
- then find the hydrogen u can remove. HAS TO BE 2 CARBONS AWAY
For our purposes, it produces constitutional isomers
Hydrocarbons: gas to solid
Alkanes with 1-4 carbons=gas=cooking & heating
Alkanes with 5-16 carbons=liquids=run devices with engines
Alkanes with 16-22 carbons=heavy liquids=lubricating oils
Alkanes with >18 carbons=semi-solids= candles, waxed paper, & cosmetics
Alkanes with >26 carbons=solid residues= asphalt & tars 4 roofing & paving
Physical Properties are
properties that can be observed without changing the composition of the matter
Intermolecular forces are
attractive forces between molecules and largely determine the physical properties of a compound
- DO NOT SAY INTERMOLECULAR BONDS
Attractive (intermolecular) forces between hydrocarbon molecules are called
london dispersion forces
- DO NOT SAY BONDS
The strength of the London Dispersion Forces depends on……
the amount of surface contact between molecules
Larger size of molecule=greater surface area=stronger LDF=requires more energy to break=higher melting & boiling points
Physical properties of Hydrocarbons: Physical state
Large hydrocarbon molecules are more attracted (closer) to each other & they tend to be solids, while smaller ones are liquid or gases due to weaker intermolecular forces
Physical properties of Hydrocarbons: Melting & Boiling Points
as the hydrocarbon gets larger, the attraction between molecules becomes stronger. More energy is needed to separate the molecules. As a result, the boiling points increase
- rmr room temp = 25 degrees celcius
Physical properties of Hydrocarbons: Solubility
hydrocarbons have very low solubility in H2O cuz they are non-polar
Distillation is
a process used to separate the various hydrocarbons in a mixture from one another by using differences in boiling points
How does Fractional Distillation work?
1) Mixture is heated @ high temp= ensures all all alcohol evaporate. Gases will condense @ diff temps (their boiling points)
2) Methanol=lowest boiling point, will evaporate 1st. As methanol travels down a fractionating column that has a large surface on which it can condense into a liquid & is collected as a condensate or distillate.
3) Once methanol has been boiled off, ethanol will be next to evaporate. This is repeated till all alcohols are boiled off & collected. Impurities that were dissolved in H2O will remain as RESIDUE in original flask
REFLUX= substances with lower boiling points travel further up the column. At the same time, others with higher boiling points drip back down
- the component liquids thus proceed at diff rates up the fractionating column so as u move up, the mixture becomes increasingly richer in the liquid with the lower boiling point
- If the substance in the mixture have boiling points that are far apart, & the fractionating column is long enough, eventually the liquid components separate completely after the other.
Fractional Distillation in Crude Oil ( substances that travel highest to lowest)
1) gases= C1-4=propane
2) Naphtha=C5-9= chemicals
3) Kerosene=C5-10
4) Diesel oil=C10-16=kerosine (paraffin oil)
5) Lubricating oil= C14-20= Diesel oils
6)fuel oil=C20-70
7) residue=>70
The most valuable hydrocarbons in petroleum aka crude oil are
C5-12 cuz they are the components of gasoline
Engine Knocking
AKA pinging or detonation, occurs when the air-fuel mixture in the combustion chamber ignites prematurely or unevenly. Instead of the fuel burning in a controlled, smooth manner after being ignited by the spark plug, pockets of the mixture explode before the spark or at the wrong time. This causes a knocking or pinging noise in the engine
Cracking
It’s a process used to break down large hydrocarbon molecules into smaller, more desirable ones like high-octane gasoline
- the hydrocarbon chains are heated to a high temp of about 400-500 alongside a catalyst.
- This heating reaction, sped up by the catalyst, breaks the chains down
- it’s an important process cuz it increases the yield of desired products from the same amount
- cracking is also used to break apart larger hydrocarbons like kerosene into smaller ones like ethane & propene (used in plastic production)
CH ratio formulas
alkanes: CnH2n+2
alkene with 1 double bond: CnH2n
alkyne with 1 triple bond: CnH2n-2
cyclo alkane: CnH2n
