Answer : The elements that has four valence electrons are hafnium (Hf) and silicon (Si).
Explanation :
Electronic configuration : It is defined as the representation of electrons around the nucleus of an atom.
Number of electrons in an atom are determined by the electronic configuration.
Atomic number : It is defined as the number of electrons or number of protons present in a neutral atom.
Valence electrons or outermost electrons : They are electrons in an atom that participate in bonding.
(a) Hafnium is a metal that belongs to group 4 and period 6. The atomic number of Hafnium is, 72.
The electronic configuration of hafnium will be,
[tex][Xe]4f^{14}5d^26s^2[/tex]
The total number of valance electrons = [2 + 2] = 4
(b) Radon is a noble gas that belongs to group 18 and period 6. The atomic number of radon is, 86.
The electronic configuration of radon will be,
[tex][Xe]4f^{14}5d^{10}6s^26p^6[/tex]
The total number of valance electrons = [2 + 6] = 8
(c) Silicon is a non-metal that belongs to group 14 and period 3. The atomic number of silicon is, 14.
The electronic configuration of silicon will be,
[tex]1s^22s^22p^63s^23p^2[/tex]
The total number of valance electrons = [2 + 2] = 4
(d) Sulfur is a non-metal that belongs to group 16 and period 3. The atomic number of sulfur is, 16.
The electronic configuration of sulfur will be,
[tex]1s^22s^22p^63s^23p^4[/tex]
The total number of valance electrons = [2 + 4] = 6
Hence, from this we conclude that, the elements that has four valence electrons are hafnium (Hf) and silicon (Si).
