Question

The ground state electron configuration of the silicon atom is characterized by which of the following?
I. Partially filled $3p$ orbitals
II. The presence of unpaired electrons
III. Six valence electrons

a.) I only
b.) II only
c.) I and II only
d.) I and III only
e.) I, II and III

Answer 1

Hint: The atomic number of Si = 14
So, its electronic configuration in ground state is ${1s}^2{2s}^2{2p}^6{3s}^2{3p}^2$
Unpaired electrons are those electrons which are present alone means they are not paired up while valence electrons are those electrons which are present in the outermost shell of an atom.

Complete step-by-step answer:

The electronic configuration of Silicon = [Ne] ${3s}^2{3p}^2$
where, Ne = Neon element with atomic number 10.

Firstly, the $3p$ orbital has 2 electrons which means it is not a fully-filled orbital. It means Si has partially filled $3p$ orbitals.
Secondly, only 2 electrons are present in $3p$ orbital which is not paired. Hence, unpaired electrons are also present in the $3p$ orbital of silicon.
Thirdly, there are 4 valence electrons present as we can see in the electronic configuration of Silicon.
Hence, I and II only are correct.

Additional information:
Valence electrons are the electrons that are present in the outermost or valence shell of an atom which can combine with other atoms of the molecules.
Here, we fill electrons according to Hund’s rule which states that “ the pairing of electrons in s,p,d and f orbitals cannot occur until each orbital of a given subshell contains one electron each orbital.
Partially filled orbital:- These are those orbitals which are filled with one or more electrons, but not fully occupied.
Half- filled orbitals:- These are those orbitals in which electrons are filled with half the number of electrons.

Note: The possibility for the mistake is that you may confuse in between partially and half filled orbitals. These two are different terms. Here, in Si, the $3p$ orbital is partially filled but not half-filled.