Organic compounds are chemical compounds which contain carbon (C). Recall that carbides, carbonates, and some oxides of carbon are NOT organic - inorganic.
Properties of Organic Compounds
- It has the ablility to link with other atoms. There are 3 different kinds of bonds;
single bonds,
double bonds,
and triple bonds,
- When they form chains of carbon, the atoms can be linked in different patterns, such as a straight line, circular parttern or a branched parrtern.
- They have a low melting point and are weak and non-electrolytes.
- The versatility of the orginial compunds make it very a important branch of chemistry.
Alkanes
- They are unbranched and have a straight chain.
- They only consist of hydrogen and carbon.
- They are saturated hydrocarbons which means that they all have carbon atoms bonded by single bonds.
- They are capable with mixing in water; they are non-polar molecules.
- Their structure/geometry; tetrahedron
Naming
When naming Alkanes, you've got to change the ending to "anes". MEMORIZE THESE!
Names of Alkanes Molecular Formula
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
Pentane C5H12
Hexane C6H14
Heptane C7H16
Octane C8H18
Nonane C9H20
Decane C10H22
People always have trouble memorizing the first four, so here is a mnenomic to help:
Maggie Enjoys Peanut Butter :)
Gerneral formula is CnH2n+2
Branched Hydrocarbons
- They can have side carbons which is also hydrocarbon chains.
- They can be called substituted hydrocarbons or just branched hydrocarbons.
- In the Alkyl group, an alkane lost one H atom, so when naming alkyl groups, the ending changes to "yl".
Ex:
Methane --> Methyl
methylpentane
the methyl part = alkyl group
the pentane part = parent hydrocarbon or longest chain
Naming
When there are more than just one type of alkyl group, you must list them alphabetically. So if there is ethyl and methyl, ethyl would come first.
*Also, when you have a side group or branched hydrocarbons, always start counting from the side that is NEAREST to the branch!
What do you mean by 'counting' ?
Well, young grasshopper, in the future you will come across names of organic compounds that have numbers in them. These numbers indicate the location of the side groups to clarify where each are (because some chains have TONS of side groups and it's hard to keep track!)
HOW TO NAME AN ALKANE (STEPS):
- Count and find the longest chain of carbons.
- Refer to the chart above to obtain the name of the alkane depending of the number of carbons.
- If there are any side groups, start counting from the side NEAREST to it!
- Write the number of the location of any side groups shown. If there are more than one of the same side group in the same location, use commas to separate them. (eg. 2,2 or 3,3,3)
- List the side groups alphabetically.
- Use a dash (-) to separate the number and the name of the side group.
- The name of the parent chain is always last!
Let's try this:
Now, take a look at the green and red numbers. Each shows an option of where to start counting. Which side is closest to the first side group?
If you answered the right side, BINGO! The red colored numbers are correct, and the green numbers are incorrect.
Now let's name it!
- Pentane = longest chain
- Ethyl (2 hydrocarbons), methyl (1 hydrocarbon) = alkyl groups
- Position of alkyl group = 3-ethyl, 2-methyl
3-ethyl-2-methylpentane
Feel that you know alkanes well enough? Challenge yourself and take this quiz!
Alrightyy, that's all the fundamentals that you need to know! Goodluck!
hubba hubba ;)
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