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Carbon binds with covalent bonds to other atoms

In methane, a central carbon atom binds to four hydrogen atoms.

  • Carbon gets noble gas structure because it "borrows" four electrons from the four hydrogen atoms.
  • Hydrogen gets noble gas structure because each hydrogen atom "borrows" one electron from the carbon atom.

Lewis structure of methane.Lewis structure of methane.

Methane and ethane: The two simplest hydrocarbons (alkanes)


  • Only contains hydrogen and carbon.
  • Only single bonds between the carbon atoms.
Name Model Structural formula Molecular formula
Methane Methane Methane.  CH4
Ethane Ethane ethane C2H6

Somewhat larger hydrocarbons

Often, the structural formula is simplified for larger molecules.

Name Model Structural formula Simplified structure Molecular formula
Propane Propane. Propane. CH3−CH2−CH3 C3H8
n-butane n-butane n-butane CH3−CH2−CH2−CH3 C4H10
n-pentane n-pentane. n-pentane.  CH3CH2CH2CH2CH3 C5H12

Even larger hydrocarbons

In a skeletal formula, the structure is simplified even more. Every line is a bond, and in every corner, there is a carbon atom. Everywhere where there's room, it is understood that there are hydrogen atoms.

Name Model Skeletal formula Molecular formula
n-hexane n-hexane. n-hexane C6H14
n-heptane n-heptane. n-hexane C7H16
n-octane n-octane n-octane C8H18
n-nonane n-nonane n-nonane. C9H20
n-decane n-decane. n-decane. C10H22


Carbon atoms joined in a circular structure.

Name Model Structure Molecular formula
Cyclopropane Cyclopropane. Cyclopropane. C3H6
Cyclobutane Cyclobutane. Cyclobutane C4H8
Cyclopentane Cyclopentane. Cyclopentane. C5H10
Cyclohexane Cyclohexane. Cyclohexane. C6H12

Cyclopropane and cyclobutane are both unstasble. This is because the binding angles differ a lot from 109°.

  • In methane, binding angles are 109°.
  • The hydrogen atoms end up in the corners of a tetrahedron.

A funny alkane


You can find more funny molecules on Molecules with Silly or Unusual Names!

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