Draw the orbital diagram for the electron configuration of oxygen, atomic number 8. How many unpaired electrons does an oxygen atom possess?
The Correct Answer and Explanation is :
The electron configuration of oxygen, which has an atomic number of 8, is:
1s22s22p41s^2 2s^2 2p^4
Orbital Diagram for Oxygen:
The orbital diagram shows the electrons arranged in orbitals with their respective spins. The energy levels are represented by horizontal lines, and electrons are represented as arrows pointing up or down. Here’s the orbital diagram for oxygen:
- 1s: ↑↓ (2 electrons in the 1s orbital)
- 2s: ↑↓ (2 electrons in the 2s orbital)
- 2p: ↑↓ ↑ (4 electrons in the 2p orbitals)
Unpaired Electrons:
From the orbital diagram above, we see that in the 2p orbitals, two of the electrons are paired (with opposite spins), and the remaining two electrons occupy separate 2p orbitals with parallel spins (unpaired). Hence, oxygen has 2 unpaired electrons.
Explanation:
The oxygen atom has 8 electrons in total. The electron configuration fills orbitals starting from the lowest energy level:
- 1s orbital: The first two electrons go into the 1s orbital. Since the 1s orbital can hold a maximum of two electrons, they are paired with opposite spins (↑↓).
- 2s orbital: The next two electrons go into the 2s orbital, which also holds a maximum of two electrons. Again, they are paired with opposite spins (↑↓).
- 2p orbitals: The remaining four electrons occupy the 2p orbitals. The 2p orbitals are degenerate, meaning they all have the same energy level. According to Hund’s rule, electrons will fill the degenerate orbitals singly first, before pairing. Thus, two electrons occupy two of the three 2p orbitals, each with parallel spins (↑), and the other two electrons fill the remaining two 2p orbitals, but they are paired (↑↓).
Thus, oxygen has 2 unpaired electrons, both in the 2p subshell.