periodic table

Question 1

The maximum attainable oxidation state generally increases across a period until a maximum is reached. However, max oxidation state of S is +4, SCl6 does not exist. Why?

Answer 1

The bulky Cl atoms will result in steric hindrance about the central S atom in SCl6, where there will be great repulsion between the electron clouds of Cl atoms

Question 2

Ionic bonding

Answer 2

When there is a large difference in electronegativity, it results in electron transfer

Question 3

AlO3 -> predominantly ionic

AlCL3 -> predominantly covalent. Why?

Answer 3

High charge density of Al3+ polarizes the large electron cloud of CL- ion, hence making it covalent in nature

Question 4

Covalent bonding

Answer 4

When there is a small difference in electronegativity, it results in electron sharing

Question 5

Does AlCl3 conduct electricity?

Answer 5

No. but it ionises in water to give mobile ions which can conduct electricity

Question 6

How does Al2Cl6 arise?

Answer 6

It is in liquid and vapour phase, AlCl3 dimerises and exists as Al2Cl6 molecule. At higher temperatures, dimer will dissociate to AlCl3 molecules

Question 7

Explanation for Acidic nature of Al3+

Answer 7

• In aq soln, Al3+ exists as hexaaqua complex ion, [Al(H2O)6]3+
  The al3+ in [Al(H2O)6]3+ has high charge density and can thus polarise the electron clouds of its surrounding water molecules, thereby weakening the OH bonds in the water molecules which results in the release of protons

Question 8

First element (Li, Be, B) of group 1,2,13:

Answer 8

Is usually exceptional in its properties

Often resembles the element diagonally below to it both physically and chemically

Question 9

What is the reason for diagonal relationships between the diagonal pairs?

Answer 9

Their similar charge density and electronegativity result in them having similar chemical properties