Chapter 7, Problem 7.120QP

The electron configurations described in this chapter all refer to gaseous atoms in their ground states. An atom may absorb a quantum of energy and promote one of its electrons to a higher-energy orbital. When this happens, we say that the atom is in an excited state. The electron configurations of some excited atoms are given. Identify these atoms and write their ground-state configurations:

1. (a) 1s¹2s¹
2. (b) 1s²2s²2p²3d¹
3. (c) 1s²2s²2p⁶4s¹
4. (d) [Ar]4s¹3d¹⁰4p⁴
5. (e) [Ne]3s²3p⁴3d¹

Interpretation Introduction

Interpretation:

The symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations should be described using the concept of electron configurations.

Concept Introduction:

The ground state is the lowest possible energy state for an atom. An excited state is any energy level higher than the ground state.  There is only one ground state energy for an atom, but there can be many possible excited states for an atom.  The ground state is called when all of the electrons of an atom are in their lowest possible energy levels/subshells.  For $\text{Li}$, the ground state configuration would be $1s^{2}2s^1$.  The excited state is called when one of the electrons has absorbed energy and jumped to a higher energy level.  For example, for $\text{Li}$ it might be $1s^{2}3p^1$.  There are many possible excited state configurations because there are many higher energy levels and subshells that the electrons can jump.

The electron configuration is the distribution of electrons of an atom or a molecule in various atomic orbitals. 

To find: Get the symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations

Answer to Problem 7.120QP

Helium ($\text{He}$) atom is involved whose ground-state configuration is $1s^2$.

Explanation of Solution

The electron configurations generally refer to gaseous atoms in their ground states.  An atom may absorb a quantum of energy and promote one of its electrons to a higher energy orbital.  When this happens, at that time the atom is in an excited state.  The given excited atoms are neutral.  Hence, the total number of electrons is the same as the atomic number of the element.

$1s^{1}2s^1$ is given.  Here, two electrons are involved.  Hence, the atomic number is 2, which correspond to helium ($\text{He}$) atom.

Two electrons are involved.  Hence, its ground-state configuration is $1s^2$ which correspond to helium ($\text{He}$) atom. 

Interpretation Introduction

Interpretation:

The symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations should be described using the concept of electron configurations.

Concept Introduction:

The ground state is the lowest possible energy state for an atom. An excited state is any energy level higher than the ground state.  There is only one ground state energy for an atom, but there can be many possible excited states for an atom.  The ground state is called when all of the electrons of an atom are in their lowest possible energy levels/subshells.  For $\text{Li}$, the ground state configuration would be $1s^{2}2s^1$.  The excited state is called when one of the electrons has absorbed energy and jumped to a higher energy level.  For example, for $\text{Li}$ it might be $1s^{2}3p^1$.  There are many possible excited state configurations because there are many higher energy levels and subshells that the electrons can jump.

The electron configuration is the distribution of electrons of an atom or a molecule in various atomic orbitals. 

To find: Get the symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations

Answer to Problem 7.120QP

Carbon ($\text{C}$) atom is involved whose ground-state configuration is $1s^{2}2s^{2}2p^2$.

Explanation of Solution

$1s^{1}2s^{2}2p^{2}3d^1$ is given.  Here, six electrons are involved.  Hence, the atomic number in (b) is 6 which correspond to carbon ($\text{C}$) atom.

Six electrons are involved.  Hence, its ground-state configuration is $1s^{2}2s^{2}2p^2$ which correspond to carbon ($\text{C}$) atom.

Interpretation Introduction

Interpretation:

The symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations should be described using the concept of electron configurations.

Concept Introduction:

The ground state is the lowest possible energy state for an atom. An excited state is any energy level higher than the ground state.  There is only one ground state energy for an atom, but there can be many possible excited states for an atom.  The ground state is called when all of the electrons of an atom are in their lowest possible energy levels/subshells.  For $\text{Li}$, the ground state configuration would be $1s^{2}2s^1$.  The excited state is called when one of the electrons has absorbed energy and jumped to a higher energy level.  For example, for $\text{Li}$ it might be $1s^{2}3p^1$.  There are many possible excited state configurations because there are many higher energy levels and subshells that the electrons can jump.

The electron configuration is the distribution of electrons of an atom or a molecule in various atomic orbitals. 

To find: Get the symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations

Answer to Problem 7.120QP

Sodium ($\text{Na}$) atom is involved whose ground-state configuration is $1s^{2}2s^{2}2p^{6}3s^1$.

Explanation of Solution

$1s^{2}2s^{2}2p^{6}4s^1$ is given.  Here, 11 electrons are involved.  Hence, the atomic number in (c) is 11 which correspond to sodium ($\text{Na}$) atom.

11 electrons are involved.  Hence, its ground-state configuration is $1s^{2}2s^{2}2p^{6}3s^1$ which correspond to sodium ($\text{Na}$) atom.

Interpretation Introduction

Interpretation:

The symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations should be described using the concept of electron configurations.

Concept Introduction:

The ground state is the lowest possible energy state for an atom. An excited state is any energy level higher than the ground state.  There is only one ground state energy for an atom, but there can be many possible excited states for an atom.  The ground state is called when all of the electrons of an atom are in their lowest possible energy levels/subshells.  For $\text{Li}$, the ground state configuration would be $1s^{2}2s^1$.  The excited state is called when one of the electrons has absorbed energy and jumped to a higher energy level.  For example, for $\text{Li}$ it might be $1s^{2}3p^1$.  There are many possible excited state configurations because there are many higher energy levels and subshells that the electrons can jump.

The electron configuration is the distribution of electrons of an atom or a molecule in various atomic orbitals. 

To find: Get the symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations

Answer to Problem 7.120QP

Arsenic ($\text{As}$) atom is involved whose ground-state configuration is $\left[\text{Ar}\right]4s^{2}3d^{10}4p^3$.

Explanation of Solution

$\left[\text{Ar}\right]4s^{1}3d^{10}4p^4$ is given where $\left[\text{Ar}\right]$ is argon core having 18 electrons in it.  Here, 33 electrons are involved.  Hence, the atomic number is 33 which correspond to arsenic ($\text{As}$) atom.

33 electrons are involved.  Hence, its ground-state configuration is $\left[\text{Ar}\right]4s^{2}3d^{10}4p^3$ which correspond to arsenic ($\text{As}$) atom.

Interpretation Introduction

Interpretation:

The symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations should be described using the concept of electron configurations.

Concept Introduction:

The ground state is the lowest possible energy state for an atom. An excited state is any energy level higher than the ground state.  There is only one ground state energy for an atom, but there can be many possible excited states for an atom.  The ground state is called when all of the electrons of an atom are in their lowest possible energy levels/subshells.  For $\text{Li}$, the ground state configuration would be $1s^{2}2s^1$.  The excited state is called when one of the electrons has absorbed energy and jumped to a higher energy level.  For example, for $\text{Li}$ it might be $1s^{2}3p^1$.  There are many possible excited state configurations because there are many higher energy levels and subshells that the electrons can jump.

The electron configuration is the distribution of electrons of an atom or a molecule in various atomic orbitals. 

To find: Get the symbols of the given atoms in which the electron configurations of excited states are given and their corresponding ground-state configurations

Answer to Problem 7.120QP

Chlorine ($\text{Cl}$) atom is involved whose ground-state configuration is $\left[\text{Ne}\right]3s^{2}3p^5$.

Explanation of Solution

$\left[\text{Ne}\right]3s^{2}3p^{4}3d^1$ is given where $\left[\text{Ne}\right]$ is neon core having 10 electrons in it.  Here, 17 electrons are involved.  Hence, the atomic number is 17 which correspond to chlorine ($\text{Cl}$) atom.

17 electrons are involved.  Hence, its ground-state configuration is $\left[\text{Ne}\right]3s^{2}3p^5$ which correspond to chlorine ($\text{Cl}$) atom.