1. Show the short-hand electron configuration for Hafnium (Hf - atomic number 72), starting from [Kr]. 2. What are the valence electrons for hafnium.
3. Explain why the 5d and 4f electrons for hafnium are not generally involved in chemical reactions.

1.  

2. The valence electrons are 4.

3. Due to poor shielding of inner electrons.

Explanation:

Electronic configuration represents the total number of electrons that a neutral element contains. We add all the superscripts to know the number of electrons in an atom.  

The element Hafnium (Hf) has atomic number of 72 and the nearest noble gas is Krypton has 36 electrons.

The electrons are filled according to Afbau's rule in order of increasing energies.

As Hafnium is a d block element amd it has 2 electrons in 5d and 2 electrons in 6s.

The eletrons in 5d and 4f are poorly shielded by the inner electrons and thus experience strong nuclear charge and thus do not participate in bonding.