Chem Is Fun ❤

Tuesday, June 7, 2011

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 C_nH_{2n+2 ,}here have another formula for Alkenes is C_nH_2n

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: C_nH_2n-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

http://www.youtube.com/watch?v=CJYzbs_vyUs

Bohr Models and Diagrams

Bohr (1920)

Protons and electrons attract each other, so that Rutherford’s models are unstable. When matter is heated, it will emit light.
.Light travels as photons (wavelength)
Each atom has different spectra of light

Bohr based his model on the emission of light. To explain this, he presumed some theory:

Electron exist in orbital or shells
Because matter is unstable. When they absorb energy, they move to a higher orbital. When they release energy, they move to a lower orbital.