The chemistry of second-period of each group differ in many important respect from that of the heavier member of the group ?What factors are responsible for this anomalous behaviour ?

There are several factors that contribute to the anomalous behavior of the second-period elements compared to the heavier members of the group. Some of these factors include:

1. Size and charge: The second-period elements are smaller in size and have a higher charge density compared to the heavier elements. This can lead to differences in bonding behavior and reactivity.

2. Electron configuration: The second-period elements have a full valence shell of electrons, which can result in different bonding patterns compared to the heavier elements that have incomplete valence shells.

3. Electronegativity: The second-period elements tend to have higher electronegativities compared to the heavier elements, which can affect their ability to form bonds and react with other elements.

4. Ionization energy: The second-period elements generally have higher ionization energies compared to the heavier elements, which can impact their ability to lose or gain electrons in chemical reactions.

5. Polarizability: The second-period elements have lower polarizabilities compared to the heavier elements, which can affect their ability to form polar covalent bonds and interact with other molecules.

Overall, these factors contribute to the unique chemical properties of the second-period elements compared to the heavier members of the group.