The Modern Periodic table in which all known elements are arranged in increasing order of atomic number. There are 18 vertical columns called groups and 7 horizontal rows called periods.
The bottom part of the periodic table contains two series of 14 elements which are called an f-block element. The left side of Modern Periodic Table mainly contains metals whereas the right side is the non-metallic region. Some elements show intermediate properties of metals and non-metals. These elements are called metalloids and are located in between metals and non-metals as a zig-zag line.
Metals can be identified as elements which are highly reactive and electropositive in nature. Unlike metals, non-metals are electronegative in nature. Carbon is one of the most common non-metals. It is basic of all organic compounds.
The double-bonded carbon atoms can be classified as vinylic and allylic carbon atoms. The general formula for vinyl group is R-CH=CH2 in which both carbon atoms are bonded with double bond and R is attached at vinylic position.
The allyic carbon atom is the sp3 hybridized carbon atom in allylic group RCH2-CH=CH2 that is bonded with -CH=CH2 group.
For example in propene, the highlighted carbon atom is allylic carbon atom (CH3-CH=CH2). Similarly, in cyclohexene, the carbon atoms next to double bond are allylic carbon atoms.
Organic compounds are composed of different elements with a parent carbon chain. Hydrocarbons are the most common organic compounds. They are composed of carbon and hydrogen mainly.
For example, in ethane molecule (CH3-CH3) both carbon atoms are bonded with one other carbon atom so both carbon atoms are primary carbon atom here. The secondary carbon atom is bonded with other two carbon atoms whereas tertiary carbon atom is bonded to three other carbon atoms.
Carbocations are ionic species which carry positive charge on carbon atom of the molecule. They usually form as an intermediate during various chemical reactions. The stability of carbocations determines by steric hindrance and +I effect of alkyl groups attached to C+ of carbocation.
As the +I effect increase of positively charged carbon atom of carbocation, it reduces the positive charge on the carbocation. So we can say that as the number of alkyl groups increases on C+, the stability of carbocation also increases.
Therefore the stability order of carbocation can be written as
Tertiary Carbocation > Secondary Carbocation > Primary Carbocation