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

The given oxygen atom has \(0\) unpaired electrons, is in an excited state, and energy will be released when it returns to the ground state.

Step-by-step solution

Identify the Oxygen Atom's Electron Configuration

The given electron configuration of the oxygen atom is \(1s^2 2s^2 2p_x^2 2p_y^2\). This notation represents the orbital filling of the electrons.

Determine the Number of Unpaired Electrons

In the electron configuration, 1s and 2s orbitals are fully occupied by two electrons each, and both 2px and 2py orbitals have two electrons each. All electrons are paired up, meaning there are \(0\) unpaired electrons.

Compare the Given Electron Configuration to the Ground State Configuration of Oxygen

The electron configuration of an oxygen atom in its ground state is given by \(1s^2 2s^2 2p^4\), which is the same as saying \(1s^2 2s^2 2p_x^2 2p_y^1 2p_z^1\). Comparing the ground state configuration to the given configuration, we can see differences in the filling of 2py and 2pz orbitals with one less electron in 2py and one more electron in 2pz.

Determine if the Atom is in an Excited State

As the given electron configuration differs from the ground state configuration, we can conclude that the oxygen atom is in an excited state.

Determine if Energy is Released or Absorbed in Returning to the Ground State

When an atom transitions from an excited state to the ground state, the excess energy stored in the excited state is released as energy, in various forms such as light, heat, or other rays. Hence, energy is released when the oxygen atom transitions from this excited state to its ground state. In conclusion, the given oxygen atom has 0 unpaired electrons, is in an excited state, and energy will be released when it returns to the ground state.

Key concepts

Unpaired Electrons

Unpaired electrons are electrons that occupy orbitals singly, without a partner. They are often found in atom's outer subshells. This oxygen atom's electron configuration is \(1s^2 2s^2 2p_x^2 2p_y^2\). In this configuration:

• Each \(1s\) and \(2s\) orbital can hold two electrons.
• The \(2p\) orbitals are split into \(2p_x\), \(2p_y\), and \(2p_z\), each capable of holding two electrons.

In this atom, the \(2p_x\) and \(2p_y\) orbitals are fully occupied by two electrons each, and the \(2p_z\) orbital is not mentioned. This means all electrons are paired. Hence, the atom has zero unpaired electrons.
Identifying unpaired electrons is crucial because they determine an atom's magnetic properties and reactivity.

Excited State

An excited state occurs when an electron configuration does not match the lowest energy arrangement of electrons around the nucleus. Atoms receive energy from external sources, pushing electrons from the ground state to higher energy levels. Comparing the configuration \(1s^2 2s^2 2p_x^2 2p_y^2\) with the ground state \(1s^2 2s^2 2p_x^2 2p_y^1 2p_z^1\), clearly, this atom has electrons only in \(2p_x\) and \(2p_y\), leaving \(2p_z\) empty.
The rearrangement from the full occupancy of \(2p_y\) without filling \(2p_z\) demonstrates an unusual configuration. This implies the atom is excited, as typical orbital fillings would have even distribution first before doubling them in an uncertain order. Knowing if an atom is in an excited state helps in understanding its potential energy transformations.

Ground State

The ground state of an atom represents the lowest possible energy configuration of its electrons. For oxygen, this configuration is typically \(1s^2 2s^2 2p_x^2 2p_y^1 2p_z^1\). In the ground state:

• Electrons fill the orbitals in a specific order determined by their energy levels.
• All lower energy orbitals are filled before higher ones begin to fill.

The given configuration, \(1s^2 2s^2 2p_x^2 2p_y^2\), differs since the normal orbital arrangement is not followed, indicating an electron was promoted without filling \(2p_z\). Understanding this configuration helps confirm stability and reactions as atoms tend to seek the ground state naturally.

Energy Transition

Energy transitions occur when atoms move from one energy level to another, such as from an excited state back down to the ground state. This change involves the release or absorption of energy. For the oxygen atom here:

• To revert to the ground state, excess energy from its excited state must be released.
• This energy can take many forms: light, heat, or even emitted particles.

In our scenario, the energy stored due to its altered electron position compared to its ground state, will be released as the atom finds its stable configuration. These transitions are fundamental in processes like combustion, photosynthesis, and light emitting devices. Understanding energy transitions clarifies many naturally occurring chemical reactions and industrial applications.