Chapter 3, Problem

How many electrons are in each energy level of the following elements?

1. a. He
2. b. C
3. c. Na
4. d. Ne

Summary Introduction

To determine:

The number of electrons in each energy level of $\text{He}$.

Introduction:

Electrons are arranged around the nucleus in an orbit so that their orbits form a shell which is known as an electron shell. The electron shell is represented as K, L, M, N, O, P, and Q in alphabets from the innermost shell to the outermost shell.

The maximum number of electrons present in each shell can be calculated by the equation, $2n^{\text{2}}$.

Explanation of Solution

Atomic number is the total number of protons present in an atom.

On basis of the periodic table of elements, the atomic number $\left(\text{Z}\right)$ of helium is $2$.

So helium has $2$ electrons that are distributed in their respective orbitals. Out of these, two electrons distribute into the $\text{1s}$ orbital.

Helium has 1 energy level $\left(\text{K}\right)$.

The number of electrons in energy level $\left(\text{K}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(1\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(1\right)}^2\\ =2\end{array}$

Therefore, the number of electrons in each energy level of $\text{He}$ is $2$.

Summary Introduction

To determine:

The number of electrons in each energy level of $\text{C}$.

Introduction:

Electrons are arranged around the nucleus in an orbit so that their orbits form a shell which is known as an electron shell. The electron shell is represented as K, L, M, N, O, P, and Q in alphabets from the innermost shell to the outermost shell.

The maximum number of electrons present in each shell can be calculated by the equation, $2n^{\text{2}}$.

Explanation of Solution

Atomic number is the total number of protons present in an atom.

On basis of the periodic table of elements, the atomic number $\left(\text{Z}\right)$ of carbon is $6$.

So carbon has $6$ electrons that are distributed in their respective orbitals. Out of these, two electrons distribute into the $\text{1s}$ orbital, two into the $\text{2s}$ orbital, and four into the $\text{2p}$ orbitals.

Carbon has $2$ energy levels $\left(\text{K}\right)$ and $\left(\text{L}\right)$.

The number of electrons in energy level $\left(\text{K}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(1\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(1\right)}^2\\ =2\end{array}$

The number of electrons in energy level $\left(\text{L}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(2\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(2\right)}^2\\ =8\end{array}$

From the above calculation, it is clear that in $\text{L}$ energy level total $8$ electrons are present. In Case of Carbon element, two electrons are present in first energy level $\left(\text{K}\right)$ and remaining four electrons are presents in second energy level $\left(\text{L}\right)$.

Therefore, the number of electrons in each energy level of $\text{C}$ is $2$ and 4.

Summary Introduction

To determine:

The number of electrons in each energy level of $\text{Na}$.

Introduction:

Electrons are arranged around the nucleus in an orbit so that their orbits form a shell which is known as an electron shell. The electron shell is represented as K, L, M, N, O, P, and Q in alphabets from the innermost shell to the outermost shell.

The maximum number of electrons present in each shell can be calculated by the equation, $2n^{\text{2}}$.

Explanation of Solution

Atomic number is the total number of protons present in an atom.

On basis of the periodic table of elements, the atomic number $\left(\text{Z}\right)$ of sodium is $11$.

So sodium has $11$ electrons that are distributed in their respective orbitals. Out of these, two electrons distribute into the $\text{1s}$ orbital, two into the $\text{2s}$ orbital, six into the $\text{2p}$ orbitals, and one into the 3s orbital.

Sodium has $3$ energy levels $\left(\text{K}\right)$ $\left(\text{L}\right)$ and $\left(\text{M}\right)$.

The number of electron in energy level $\left(\text{K}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(1\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(1\right)}^2\\ =2\end{array}$

The number of electrons in energy level $\left(\text{L}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(2\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(2\right)}^2\\ =8\end{array}$

The number of electrons in energy level $\left(\text{M}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(3\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(3\right)}^2\\ =18\end{array}$

From the above calculation, it is clear that in $\text{M}$ energy level total $18$ electrons are present. In Case of Sodium element, two electrons are present in first energy level $\left(\text{K}\right)$, eight electrons are present in second energy level $\left(\text{L}\right)$ , and remaining one electron is presents in third energy level $\left(\text{M}\right)$.

Therefore, the number of electrons in each energy level of $\text{Na}$ is $2$, $8$ , and $1$.

Summary Introduction

To determine:

The number of electrons in each energy level of $\text{Ne}$.

Introduction:

Electrons are arranged around the nucleus in an orbit so that their orbits form a shell which is known as an electron shell. The electron shell is represented as K, L, M, N, O, P, and Q in alphabets from the innermost shell to the outermost shell.

The maximum number of electrons present in each shell can be calculated by the equation, $2n^{\text{2}}$.

Explanation of Solution

Atomic number is the total number of protons present in an atom.

On basis of the periodic table of elements, the atomic number $\left(\text{Z}\right)$ of neon is $10$.

So neon has $10$ electrons that are distributed in their respective orbitals. Out of these, two electrons distribute into the $\text{1s}$ orbital, two into the $\text{2s}$ orbital, and six into the $\text{2p}$ orbitals.

Sodium has $2$ energy levels $\left(\text{K}\right)$ and $\left(\text{L}\right)$.

The number of electrons in energy level $\left(\text{K}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(1\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(1\right)}^2\\ =2\end{array}$

The number of electrons in energy level $\left(\text{L}\right)$ is calculated by the formula,

$\text{The}\text{number}\text{of}\text{electrons}=2n^2$

Where,

• $n$ is the number of energy level $\left(2\right)$.

Substitute the value of the number of energy shell in the above expression.

$\begin{array}{c}\text{The}\text{number}\text{of}\text{electrons}=2n^2\\ =2{\left(2\right)}^2\\ =8\end{array}$

Therefore, the number of electrons in each energy level of $\text{Na}$ is $2$, and $8$.