According to Hund’s rules, the lowest (ground) state of the silicon atom…..
has four unpaired electrons
has three sets of paired electrons
has 2 unpaired electrons
has three different orbitals less than fully occupied
The correct answer and explanation is :
The correct answer according to Hund’s rules is:
Has four unpaired electrons.
Explanation:
Hund’s rules are used to determine the electron configuration of an atom in its ground state. These rules guide how electrons fill the atomic orbitals of a particular atom, specifically regarding the distribution of electrons among orbitals in the same energy level. The rules are as follows:
- The maximum multiplicity: Electrons will fill orbitals in a way that maximizes the total spin. This means that electrons will first occupy separate orbitals within a given subshell, with the same spin direction, before pairing up. This is referred to as the “Hund’s rule of maximum multiplicity.”
- The lowest energy configuration: Once the maximum multiplicity is achieved, the electrons will fill orbitals in a way that minimizes the overall energy of the atom. The energy is minimized when electrons are as far apart as possible in space, which is why they occupy separate orbitals before pairing.
- For degenerate orbitals (orbitals of the same energy level), electrons will first fill each orbital singly, with parallel spins, before any orbital is doubly occupied. This minimizes electron-electron repulsion and leads to the most stable configuration.
Now, let’s apply these rules to the silicon atom. Silicon has an atomic number of 14, meaning its electron configuration is:
[ \text{Si}: 1s^2 2s^2 2p^6 3s^2 3p^2 ]
The electron configuration shows that the last two electrons occupy the 3p subshell. According to Hund’s rules, these electrons will not pair up in the same orbital; instead, they will occupy separate orbitals with parallel spins, leaving four unpaired electrons in the 3p orbitals.
Thus, the ground state of a silicon atom has four unpaired electrons. These four electrons are distributed across the three 3p orbitals, in accordance with Hund’s rules, which maximize the number of unpaired electrons to achieve a lower energy configuration.
In summary, the silicon atom in its ground state will have four unpaired electrons in its 3p orbitals, as dictated by Hund’s rules.