Summary & Quick Quiz കാർബണിക രസതന്ത്രം
The whole chapter on one page: the chapter in eight pictures, a facts & rules card for the three families of hydrocarbons with their general formulas, word roots and suffixes with a name machine, homologous series, ring compounds, the fuels table, the forms of coal, greenhouse gases, the mistakes to avoid, flashcards, a scored quiz and your study checklist.
1. The chapter in eight pictures
2. Facts & rules card
C Organic compounds & hydrocarbons ഓർഗാനിക് സംയുക്തങ്ങൾ
- Organic
- compounds of carbon – except CO, CO2, carbonates and bicarbonates. There are far more carbon compounds (about ten times more) than compounds of all the other elements together.
- History
- Berzelius named organic chemistry and believed in a vital force (ജീവശക്തി). Wöhler (1828) made urea from ammonium cyanate; Kolbe (1845) acetic acid; Berthelot (1856) methane – the vital force theory ended.
- Carbon
- Table 8.1: Z = 6; electron configuration 2, 4; valency 4. Carbon shares electrons: covalent bonds.
- Key box
- a compound of only carbon and hydrogen (ഹൈഡ്രോകാർബണുകൾ). Bonds between carbons: single C–C (ഏകബന്ധനം), double C=C (ദ്വിബന്ധനം), triple C≡C (ത്രിബന്ധനം).
- Formulae
- structural formula (ഘടനാവാക്യം) – every bond drawn; condensed formula (കണ്ടൻസ്ഡ് ഫോർമുല) – CH3–CH2–CH3; molecular formula (തന്മാത്രാസൂത്രം) – C3H8.
-ane Alkanes ആൽക്കെയ്നുകൾ
| C | name | condensed formula | molecular | state |
|---|---|---|---|---|
| 1 | methane | CH4 | CH4 | gas |
| 2 | ethane | CH3–CH3 | C2H6 | gas |
| 3 | propane | CH3–CH2–CH3 | C3H8 | gas |
| 4 | butane | CH3–CH2–CH2–CH3 | C4H10 | gas |
| 5 | pentane | CH3–CH2–CH2–CH2–CH3 | C5H12 | liquid |
| 6 | hexane | CH3–CH2–CH2–CH2–CH2–CH3 | C6H14 | liquid |
Key box: open-chain hydrocarbons with only single bonds between carbon atoms.
-ene Alkenes ആൽക്കീനുകൾ
| C | name | condensed formula | molecular | state |
|---|---|---|---|---|
| 2 | ethene | CH2=CH2 | C2H4 | gas |
| 3 | propene | CH2=CH–CH3 | C3H6 | gas |
| 4 | butene | CH2=CH–CH2–CH3 | C4H8 | gas |
| 5 | pentene | CH2=CH–CH2–CH2–CH3 | C5H10 | liquid |
| 6 | hexene | CH2=CH–CH2–CH2–CH2–CH3 | C6H12 | liquid |
Key box: hydrocarbons with at least one double bond between two carbon atoms. First member: ethene.
-yne Alkynes ആൽക്കൈനുകൾ
| C | name | condensed formula | molecular | state |
|---|---|---|---|---|
| 2 | ethyne | CH≡CH | C2H2 | gas |
| 3 | propyne | CH≡C–CH3 | C3H4 | gas |
| 4 | butyne | CH≡C–CH2–CH3 | C4H6 | gas |
| 5 | pentyne | CH≡C–CH2–CH2–CH3 | C5H8 | liquid |
| 6 | hexyne | CH≡C–CH2–CH2–CH2–CH3 | C6H10 | liquid |
Key box: hydrocarbons with at least one triple bond between two carbon atoms. First member: ethyne.
Every carbon atom has exactly four bonds (valency 4). A double bond counts as two, a triple bond as three. To find the family from a molecular formula, count the carbons (n) and compare the hydrogens: 2n + 2 → alkane, 2n → alkene, 2n − 2 → alkyne.
3. Word roots, suffixes and the name machine നാമകരണം · പദമൂലം · പ്രത്യയം
IUPAC (International Union of Pure and Applied Chemistry, founded 1919) names a hydrocarbon from two things: the number of carbon atoms gives the word root, and the kind of bond between carbons gives the suffix – -ane (single), -ene (double), -yne (triple).
| C | word root | alkane (-ane) | alkene (-ene) | alkyne (-yne) | alkane formula |
|---|---|---|---|---|---|
| 1 | meth | methane | — | — | CH4 |
| 2 | eth | ethane | ethene | ethyne | C2H6 |
| 3 | prop | propane | propene | propyne | C3H8 |
| 4 | but | butane | butene | butyne | C4H10 |
| 5 | pent | pentane | pentene | pentyne | C5H12 |
| 6 | hex | hexane | hexene | hexyne | C6H14 |
| 7 | hept | heptane | heptene | heptyne | C7H16 |
| 8 | oct | octane | octene | octyne | C8H18 |
| 9 | non | nonane | nonene | nonyne | C9H20 |
| 10 | dec | decane | decene | decyne | C10H22 |
4. Homologous series ഹോമലോഗസ് ശ്രേണി
- All members can be written with one general formula.
- Neighbouring members differ by –CH2– (1 carbon and 2 hydrogens).
- They have similar chemical properties.
- Their physical properties change gradually (gas → liquid as the chain grows).
5. Ring compounds വലയസംയുക്തങ്ങൾ
| ring compound | molecular formula | kind |
|---|---|---|
| cyclopropane | C3H6 | alicyclic |
| cyclobutane | C4H8 | alicyclic |
| cyclobutene | C4H6 | alicyclic |
| cyclopentane | C5H10 | alicyclic |
| cyclopentene | C5H8 | alicyclic |
| cyclohexane | C6H12 | alicyclic |
| benzene | C6H6 | aromatic |
| naphthalene | C10H8 | aromatic |
Benzene box: Michael Faraday discovered benzene in 1825; August Kekulé proposed (1865) its ring of six carbons with alternating double bonds. Catenation (കാറ്റിനേഷൻ): the ability of atoms of one element to join each other – carbon has it most. Reasons for so many carbon compounds: catenation, valency 4, single/double/triple bonds, chains, branches and rings, bonds with H, O, N and halogens.
6. Fuels: petroleum, coal and natural gas ഫോസിൽ ഇന്ധനം
Petroleum (crude oil, പെട്രോളിയം · ക്രൂഡ് ഓയിൽ) is a mixture of hydrocarbons – a fossil fuel found deep between hard rocks, formed from the remains of living things over thousands of years. It is separated by fractional distillation (അംശികസ്വേദനം) in a fractionating tower (ഫ്രാക്ഷണേറ്റിങ് ടവർ): hottest at the bottom (about 350 °C), coolest at the top (about 50 °C).
Table 8.9 – fractions and uses
| fraction | carbon atoms | uses |
|---|---|---|
| gases | C1–C4 | domestic and industrial fuel |
| petrol | C5–C10 | motor fuel |
| naphtha | C8–C12 | fuel in thermal power stations |
| kerosene | C10–C16 | domestic fuel |
| diesel | C16–C20 | fuel for diesel engines |
| petroleum jelly (vaseline), grease | C20–C50 | lubricant; making cosmetics |
| fuel oil | C50–C70 | fuel in thermal power stations, ships, industrial furnaces and boilers |
| paraffin wax | C60–C70 | making candles, boot polish, wax paper and tarpaulin sheets |
| bitumen | above C70 | road tarring |
Key box: the number of carbon atoms and the structure of the carbon chain are the main factors that decide the properties of a fuel. LPG (എൽ.പി.ജി) is mainly butane, C4H10, an alkane.
Coal കൽക്കരി · കാർബണൈസേഷൻ
Carbonisation: plant remains turn into carbon at high temperature and pressure in the absence of air. Coal is used as a fuel; to make coke, coal tar and coal gas; as a source of aromatic compounds (benzene, naphthalene, phenol); for synthetic petrol; and for some fertilisers, medicines and perfumes.
| form of coal | carbon |
|---|---|
| anthracite | 94 % |
| bituminous coal | 83 % |
| lignite | 67 % |
| peat | 57 % |
Natural gas പ്രകൃതിവാതകം
Mainly methane. CNG (സി.എൻ.ജി) – compressed natural gas, filled at high pressure, for less-polluting vehicles. LNG (എൽ.എൻ.ജി) – liquefied natural gas, made liquid at very high pressure. It causes less carbon pollution – eco-friendly. GAIL supplies natural gas in Kerala.
7. Greenhouse gases and global warming ആഗോളതാപനം
The warm Earth gives out infrared rays (ഇൻഫ്രാറെഡ് രശ്മികൾ). Greenhouse gases (ഹരിതഗൃഹവാതകങ്ങൾ) – CO2, CH4, N2O, CFCs (also ozone and water vapour) – trap part of them: the greenhouse effect (ഹരിതഗൃഹപ്രഭാവം), which keeps the Earth warm. Extra greenhouse gases raise the average temperature of the Earth and its atmosphere: global warming. Nitrogen is not a greenhouse gas.
Table 8.10
| greenhouse gas | share in global warming | increase every year |
|---|---|---|
| carbon dioxide (CO2) | 55 % | 0.5 % |
| methane (CH4) | 15 % | 0.9 % |
| nitrous oxide (N2O) | 6 % | 0.3 % |
| chlorofluorocarbons (CFCs) | 10–24 % | 4 % |
Effects: melting ice, rising sea level, extreme rain and floods, droughts, crop loss, health problems, coral bleaching. Remedies: burn less fossil fuel; use solar and wind energy; public transport, CNG and electric vehicles; save energy; plant trees and protect forests and wetlands; CFC-free appliances.
- Drawing a carbon with 3 or 5 bonds. Count every carbon in your drawing: always 4 (a double bond counts 2, a triple bond 3).
- Mixing up the general formulas. Alkane 2n + 2, alkene 2n, alkyne 2n − 2 – check with ethane C2H6, ethene C2H4, ethyne C2H2.
- Calling CO2 or CaCO3 organic compounds. CO, CO2, carbonates and bicarbonates are not counted as organic.
- Naming propene “propane”. Check the bond: -ane single, -ene double, -yne triple.
- Thinking homologues differ by “CH3”. The step is –CH2– (1 C and 2 H).
- Forgetting “cyclo” for ring compounds, or thinking benzene and cyclohexane have the same formula (C6H6 vs C6H12).
- Saying nitrogen is a greenhouse gas. It is not; CO2, CH4, N2O and CFCs are.
- Thinking the greenhouse effect itself is bad. It keeps the Earth warm; the extra greenhouse gases cause global warming.
Petrol, kerosene and LPG are flammable – never play with them. Naphthalene and benzene are toxic – keep moth balls away from small children.
8. Flashcards
Click a card to flip it.
9. Scored quiz
Answer all sixteen, then press Check my answers. Each wrong answer shows the page to revise. For number answers type only the number.
10. Your study checklist
Ticks come from “Mark this page as completed” at the bottom of each page.
Next: the model test paper ▶ – attempt it on paper with a timer first, then check with the solved paper.