Question

A certain oxygen atom has the electron configuration \(1 s^{2} 2 s^{2} 2 p_{x}^{2} 2 p_{y}^{2} .\) How many unpaired electrons are present? Is this an excited state of oxygen? In going from this state to the ground state, would energy be released or absorbed?

Short answer

There are 0 unpaired electrons in the given oxygen atom's electron configuration, which is an excited state. When transitioning from this excited state to the ground state, energy would be released.

Step-by-step solution

Recap the electron configuration rules

Atoms fill their electron orbitals following three rules: 1. Aufbau Principle: Electrons fill the lowest energy level orbitals available first. 2. Pauli Exclusion Principle: Each orbital can contain at most two electrons with opposite spins. 3. Hund's Rule: When filling degenerate orbitals (orbitals with the same energy), electrons are distributed to maximize the number of unpaired electrons before electrons begin to pair up in orbitals.

Analyze the given electron configuration

The given electron configuration for the oxygen atom is: \(1s^2 2s^2 2p_x^2 2p_y^2\) This means there are 2 electrons in the 1s orbital, 2 electrons in the 2s orbital, and 4 electrons distributed between the 2px and 2py orbitals.

Determine the number of unpaired electrons

The given electron configuration shows that all electrons in the orbitals are paired, as there are no unpaired electrons in the 1s, 2s, or 2p orbitals. Thus, there are 0 unpaired electrons in the atom.

Determine if the given configuration is the ground state or an excited state

A ground state configuration is when the electrons are in the lowest energy level possible. For an oxygen atom, which has 8 electrons, the ground state configuration should be \(1s^2 2s^2 2p^4\). Comparing this to the given configuration: Given: \(1s^2 2s^2 2p_x^2 2p_y^2\) Ground State: \(1s^2 2s^2 2p^4\) The given configuration does not match the ground state configuration. Specifically, the given configuration has spread the 4 2p electrons between the 2px and 2py orbitals only, not considering the 2pz orbital, thus violating Hund's Rule. This means that the given configuration is an excited state.

Determine if energy is released or absorbed in going from this state to the ground state

When an atom transitions from an excited state to a ground state, it releases energy. This is because the electrons in the excited state are at a higher energy level than the ground state, so as they return to their lowest energy level, the excess energy is emitted. In this case, energy would be released when the oxygen atom transitions from the given electron configuration to its ground state configuration.