VSEPR calculation for propene, CH3CH=CH 2

The first is a ring called cyclopropane. It is also possible to draw three carbons in a line with a double bond. Both Lewis structures are correct for C3H6. After determining how many valence electrons there are in C3H6, place them around the central atom to complete the octets.

The diatomic fluorine molecule (F2) contains a single shared pair of electrons. Each F atom also has three pair of electrons that are not shared with the other atom. A lone pair is a pair of electrons in a Lewis electron-dot structure that is not shared between atoms.

C3H4

The general formula for alkynes is CnH2n-2. Acetylene is the simplest alkyne with the formula as C2H2.

The first four alkanes are methane (CH4), ethane (C2H6), propane (C3H8) and butane (C4H10).

Alkane can be prepared from alkene and alkyne through the process of hydrogenation. In this process, dihydrogen gas is added to alkynes and alkenes in the present catalyst. This catalysts which are finely divided is like nickel, palladium or platinum to form alkanes.

Paraffin is a truncation of Latin ‘parum affinum’ meaning ‘less affinity’ i.e. ‘less reactivity’. Hence, alkanes are called paraffins because they have lesser affinity towards general reagents. In other words they are inert, not readily active.

In general, alkanes show a relatively low reactivity. Lower alkanes in particular are highly flammable and form explosive mixtures (methane, benzene) with air (oxygen). Solubility of alkanes in water is very low.

Alkanes undergo a substitution reaction with halogens in the presence of light. For instance, in ultraviolet light , methane reacts with halogen molecules such as chlorine and bromine. This reaction is a substitution reaction because one of the hydrogen atoms from the methane is replaced by a bromine atom.

Combustion Reactions – burn them – destroying the entire molecule; Halogenation Reactions (substitution type) – react them with some of the halogens, breaking the carbon-hydrogen bonds; Cracking Reactions – use heat and/or a catalyst to crack alkanes, breaking carbon-carbon bonds.

Alkenes react in many addition reactions, which occur by opening up the double-bond. Examples are hydrohalogenation, halogenation, halohydrin formation, oxymercuration, hydroboration, dichlorocarbene addition, Simmons–Smith reaction, catalytic hydrogenation, epoxidation, radical polymerization and hydroxylation.

Hydrocarbons with only single bonds are called alkanes. Alkanes are called saturated hydrocarbons because each carbon is bonded with as many hydrogen atoms as possible. Potassium permanganate will not react with alkanes since they are saturated.

Cyclohexane, cyclohexene, and cyclohexanol are added to potassium permanganate solution. Cyclohexane does not react. The secondary alcohol cyclohexanol is oxidized by permanganate to give the ketone cyclohexanone. The alkene cyclohexene reacts to give cis-1,2-cyclohenanediol.