Which of these elements has four valence electrons? hafnium radon silicon sulfur

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,

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,

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,

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,

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).

definition

                    entropy is a measure of the randomness or the extent of disorder of a chemical process.

                      enthalpy is a measure of the heat change of a reaction occurring at a constant pressure.

measurement units:

                        entropy is measured in joule per kelvin (jk⁻¹)   whereas enthalpy is measured in joule per mole (jmol⁻¹)

requirements:

                            entropy has no requirements or limits, and its change is measured by the division between the heat change of the chemical process and the temperature.

                              in contrast, enthalpy can only be related to the heat change of the reaction under standard conditions.