Tuesday, June 7, 2011

Alkenes and Alkynes (Double & Triple bonds)

Alkenes and Alkynes (Double & Triple bonds)
-Each carbon can have 4 bonds:
 Carbon can form double & triple bonds with carbon atoms, when multiple bonds form, fewer hydrogen will attach the carbon atom
-The position of the double/triple bonds always has the lowest number and is put in front of the parent chain. Ex.
2-pentene
1-pentene 
-Naming rules are almost same as Alkanes, just change –ane to –ene foe Alkenes
For example CH2=CH2 ehene CH2=CH–CH3 1-propene or propene
-as we know, the general formula for Alkanes is CnH2n+2 , here have another formula for Alkenes  is CnH2n
Naming rules:
1) Find the longest chain and place it at the end of the name
2) Number the carbon atoms to get the lowest number for the start of the double bond and place that number before the parent name.
3) Assign names and numbers for all side groups and assemble the name alphabetically (videos)http://www.youtube.com/watch?v=KWv5PaoHwPA
Alkenes: some molecules will have the same structure, but have different geometry.-these called geometric isomers
-          trans & cis butane  eample:
.
1. If the larger groups are both above H or below R the plane of the bond, the double bond is termed a “cis” double bond
2. If the larger groups are across the plane of the bond (H or R), the double bond is termed a “trans” double bond
3. If there are two identical groups on either end of the double bond (H or R), there are no geometric isomers, and no need for cis or trans in the name
Alkynes (hydrocarbons)- triple bonds between carbon atom  (-yne for alkynes)
-Naming rules: (general formula: CnH2n-2)
The naming rules are “mostly” the same as the alkenes (with no cis or trans!)
1) Find the longest chain (and write at the end)
2) Number the carbon atoms to get the lowest number for the start of the triple bond and write that number before the parent name
3) Assign names and numbers for all side groups and assemble the name alphabetically
Double bonds (Alkenes) end in –ene Triple bonds (Alkynes) end in -yne

Bohr Models and Diagrams

Bohr (1920)
  1. Protons and electrons attract each other, so that Rutherford’s models are unstable. When matter is heated, it will emit light.
  2. .Light travels as photons (wavelength)
  3.  Each atom has different spectra of light
Bohr based his model on the emission of light. To explain this, he presumed some theory:
  1. Electron exist in orbital or shells
  2.  Because matter is unstable. When they absorb energy, they move to a higher orbital. When they release energy, they move to a lower orbital.
Protons=11    Atomic Mass= 23.0  
Neutrons=23-11=12      (one valence electron) - so sodium always form an ion with 1+ charge
- Two different models can be used to describe electron configuration:
1. Energy Level Model
2. Bohr Model
-Here are some rules about how electrons occupy shells:
  1. 2 e- in the first orbital
  2.  8 e- in the second orbital
  3.  8 e- in the third orbital
-the electrons were absorbing and then emitting energy from different energy levels around the atoms and proposed his model of the atom

Sunday, June 5, 2011

Organic Chemistry--Functional Groups

Functional Groups are organic compounds can contain elements other than C and H.

Ex. Alcohols, Halides and Nitro, Aldehydes, Ketones


Halides and Nitro Compounds

- they can be attached  to alkanes, alkenes, and alkynes
- add the following prefixes in front of the main chain:
F: fluoro
Cl: chloro
Br: bromo
I: iodo
NO2: nitro



Ex. 1, 2, 3-trichloropentane








Alcohols
- contains an -OH functional group
- when naming an alcohol, use the longest chain that contains the OH group
- the "e" ending in the parent hydrocarbon is replaced by "ol"
Ex. 3-ethyl-2-pentanol


- If there are more than one -OH group, add -diol, -triol, etc. endings

Ex. 1,2-butanediol







Aldehydes:
- a compound that contains a double bond oxygen at the end of a chain
- change the parent ending to "-al"

Ex. propanal




Ketones:

- a compound that contains a double bond oxygen that is not on either end
- add "-one" ending to the parent hydrocarbon

Ex. 4-methyl-3-heptanone