Question

Question 1:

Description: Ligands can interact with a metal in a variety of different oxidation states. All that is needed is a set of lone pair electrons. This brings up an interesting question as to what type of interaction is actually occurring here.

Prompt: In many cases, a negatively charged compound (ex Cl-) will interact with a positively charged metal (ex Fe2+). Usually we would consider this type of interaction to be ionic, but in the case of metals we do not. What type of bond is being formed when a ligand interacts with a metal and how could you know that the bond you are forming is that type of bond? Why do we not label this interaction as ionic?

Question 2:

Description: Different atoms have the ability to make different numbers of bonds. Carbon in particular is known to only make 4 bonds whereas most metals can make upwards to 6 bonds to different ligands.

Prompt: Would it be hypothetically possible for a atom to make 8 bonds? Explain your reasoning

Answer 1

question 1:

In Crystal field theory the metal ion is considered to be a point positive charge and the negative ligands are considered to be a point negative charge and the interaction between them are considered to be purely electrostatic.

But according to Valence bond theory this is not the case. The metal is considered to be a lewis acid and the ligand is considered to be a lewis base.The ligand donates its electrons in the vacant orbital of the metal and form coordinate bond with it. we can not label this type of bond as ionic because of absence of opposite charges.

NOTE: in many cases pi bonding also occurs between metal and the ligand.

Question 2:

All the elements of the second period can have maximum 8 electrons in their outermost shell because of the absence of empty d-orbitals but the elements of the further period can expand their octet.

An element can only make 8 bonds if it uses all of its s,p and d orbitals which is only hypothetically possible because in actual observation no such hybridisation exists which uses all the s , p and d orbitals.