How to make a Bohr Model diagram of an atom? |Bohr-Rutherford Diagrams|

Home  > Chemistry > How to draw Bohr-Rutherford diagram?

How to draw a Bohr model of atom?

Bohr diagram or Bohr rutherford diagram describes the visual representation of orbiting electrons around the small nucleus. It used different electron shells such as K, L, M, N…so on. These shells hold a specific number of electrons, the electron shell which is closest to the nucleus has less energy and the electron shell which is farthest from the nucleus has more energy.

In this article, we will study How to draw the Bohr model for an atom?

Bohr model or Rutherford–Bohr diagram, presented by Niels Bohr and Ernest Rutherford in 1913.

Bohr model of an atom consists of a small nucleus that contains protons and neutrons, this nucleus is surrounded by different electron shells or energy levels where electrons are revolved in a definite circular path “similar to the structure of the Solar System“.

How to draw Bohr-Rutherford diagram

Protons are the positively charged particles and neutrons are the uncharged particles, both these are constituents of the atom nuclei. Electrons are negatively charged particles that orbit the nucleus of an atom.

“An electron shell may be thought of as an orbit followed by electrons around an atom’s nucleus”

Electron shells are also called the energy level, the electron shell located furthest from the nucleus region has more energy, and the electron shell(n=1) which is the closest to the nucleus region has less energy.

  • Each electron shell holds a specific number of electrons and calculates by the 2n2 formula where n represents the shell number.
  • The closest electron shell to the nucleus region is K-shell or 1st shell(n=1), hence, it can hold 2(1)2 = 2 maximum electrons.
  • The 2nd shell(n=2) or L-shell is drawn after the 1st shell and can hold 2(2)2 = 8 maximum electrons.
  • The 3rd shell(n=3) or M-shell holds 2(3)2 = 18 maximum electrons.
  • The 4th shell(n=4) or N-shell holds 2(4)2 = 32 maximum electrons…..and so on.

How to draw Bohr Model of an atom?

Bohr diagram is very interesting and easy to draw.

Let’s see How to draw a Bohr diagram of an atom? To draw the Bohr model of an atom, follow these basic steps.

  1. Find the number of protons, electrons, and neutrons of an atom.
  2. Draw the nucleus of an atom.
  3. Write the number of protons and neutrons at the center of the nucleus.
  4. Draw the first electron shell and put the electrons as a dot in it.
  5. Draw the second electron shell, third electron shell….and so on, depending on the availability of the number of electrons.

Let’s take an example of the Fluorine atom to understand the “Concept of making Bohr model for an atom”.

Steps to draw the Bohr Model of the atom

1. Find the number of protons, electrons, and neutrons

The number of protons for the atom is the same as its atomic number.

So, the atomic number for Fluorine is 9, hence, the number of protons in the Fluorine atom is also 9.

Now, to determine the number of neutrons in an atom, use this formula.

Number of neutrons in atom = Atomic mass of the atom(rounded to the nearest whole number) – Number of proton in an atom

Now, To get the number of neutrons in a Fluorine atom, look at its atomic mass which is 18.998 rounded to 19, and the number of protons in Fluorine is 9.

∴ Hence, the number of neutrons in Fluorine atom = (19 – 9) = 10 neutrons

Find the number of protons and neutrons of an atom

It should be noted that “The number of electrons in a neutral atom is equal to the number of protons”.

So, the Fluorine atom is neutral, hence, its number of electrons will be equal to the number of protons which is Nine as we already discussed.

⇒ The number of electrons in Fluorine atom = 9

⇒ The number of protons in Fluorine atom = 9

⇒ The number of neutrons in Fluorine atom = 10

Let’s read in detailHow to find number of protons, electrons, neutrons?

2. Draw the nucleus of an atom

In this step, we have to draw a small circle that consists of a number of protons and the number of neutrons of a Fluorine atom.

Draw the nucleus of atom

3. Draw the First electron shell

The first electron shell is also called the K-shell, this is the closest shell to the nucleus of an atom and can hold a maximum of two electrons.

As we know, the Fluorine atom has a total of 9 electrons. So, put two electrons from it, in the first shell, next to each other.

Draw the first electron shell and put the electrons as a dot in it

As Fluorine atoms have a total of 9 electrons, and from 9 electrons we have used two electrons in the first shell.

∴ (9 – 2) = 7 electrons 

Therefore, we are left with 7 electrons, let’s put them in the next shell of the fluorine atom.

4. Draw the Second electron shell

The second shell also called the L-shell that can hold a maximum of 8 electrons. This shell is drawn after the first electron shell.

Since we already used two electrons in the first shell, now, we have to put the remaining 7 electrons in the second shell.

In the second electron shell, the electrons are added one at a time, starting from the top position then going in a clockwise direction.

In second shell, electrons are added one at a time in clockwise direction as a clock position – 12 o’clock, 3 o’clock, 6 o’clock, 9 o’clock positions.

electrons placing position in bohr diagram

Once you place the electrons one at a time to each of the four sides(Top – Right – Bottom – Left], start pairing or doubling them.

So, we have to put 7 remaining electrons of the Fluorine atom in the second shell, hence, start from the top position, put electrons one at a time, and go in a clockwise direction(Top – Right – Bottom – Left). And, finally, start pairing.

How to draw Bohr model of the Fluorine atom

That’s all, this is our Bohr model of the Fluorine atom that contains 9 protons and 10 neutrons in the nucleus region, and 9 electrons are orbited around the nucleus, two electrons in the first shell, and seven electrons in the second shell.

Let’s take another example and draw the Bohr model for the Phosphorus atom.

1. Find the number of protons, electrons, and neutrons

The atomic number for Phosphorus is 15, hence, the number of protons in the Phosphorus atom is also 15.

Now, To get the number of neutrons in a Phosphorus atom, look at its atomic mass which is 30.97 rounded to 31, and the number of protons in Phosphorus is 15.

∴ Hence, the number of neutrons in Phosphorus atom = (31 – 15) = 16 neutrons

Determine the number of protons and neutrons of an atom

The Phosphorus atom is neutral, hence, its number of electrons will be equal to the number of protons which is 15 as we already discussed.

⇒ The number of electrons in the Phosphorus atom = 15

⇒ The number of protons in the Phosphorus atom = 15

⇒ The number of neutrons in the Phosphorus atom = 16

2. Draw the nucleus of an atom

In this step, we have to draw a small circle that consists of a number of protons and the number of neutrons of a Phosphorus atom.

Draw the small nucleus of an atom

3. Draw the First electron shell

As we know, the Phosphorus atom has a total of 15 electrons. So, put two electrons from it, in the first shell, next to each other.

Draw the first electron shell of Bohr diagram

As a Phosphorus atom has a total of 15 electrons, and from 15 electrons we have used two electrons in the first shell.

∴ (15 – 2) = 13 electrons 

Therefore, we are left with 13 electrons, let’s put them in the next shells of the Phosphorus atom.

4. Draw the Second electron shell

So, we have 13 remaining electrons of a Phosphorus atom, and the 2nd shell can only hold a maximum of 8 electrons.

Therefore, put the 8 electrons of the Phosphorus atom in the 2nd electron shell, start from the top position, put electrons one at a time, and go in a clockwise direction(Top – Right – Bottom – Left). And, finally, pair them up.

draw the second electron shell of Bohr model

As we have a total of 15 electrons for the Phosphorus atom and we placed 2 electrons in the first shell and 8 electrons in the second shell, hence, we are left with 5 electrons more.

Let’s place it in the next shell.

5. Draw the Third electron shell

The third shell is also called the M-shell and it has the capacity to hold up to 18 electrons but, for the elements in the first few periods, the third shell only holds up to 8 electrons.

“The third shell can be considered to hold 8 or 18 electrons but in total the third shell can hold 18 electrons.”

For the first few elements, say, till atomic number 20 on the periodic table, the third shell holds up to 8 electrons.

⇒ For atomic number 20 or less than 20, the third shell can hold up to maximum of 8 electrons.

⇒ For the atomic number more than 20, say, atomic numbers 21, 22, 23, 24, 25, 26, 27,…….etc., the third shell is filled with more than 8 electrons and up to maximum of 18 electrons.

For the Phosphorus atom, the third shell is filled with the same procedure as the second shell.

So, we have left with only 5 electrons of a Phosphorus atom, so, start from the top position, put electrons one at a time, and go in a clockwise direction(Top – Right – Bottom – Left). And, finally, start pairing.

How to draw the Bohr model of phosphorus atom

∴ This is our Bohr model of the Phosphorus atom that contains 15 protons and 16 neutrons in the nucleus region, and 15 electrons are orbited around the nucleus, two electrons in the first shell, eight electrons in the second shell, and five electrons in the third shell.

Let’s take an example of a difficult one and try to draw the Bohr model for the Scandium atom.

Steps to draw the Bohr Model of Scandium atom

1. Find the number of protons, electrons, and neutrons in the Scandium

The atomic number for Scandium is 21, hence, the number of protons in the Scandium atom is also 21.

 

number of protons in scandium

Now, To get the number of neutrons in a Scandium atom, look at its atomic mass which is 44.95 rounded to 45, and the number of protons in Scandium is 21.

∴ Hence, the number of neutrons in Scandium atom = (45 – 21) = 24

number of neutrons in scandium bohr diagram

So, the Scandium atom is neutral, hence, its number of electrons will be equal to the number of protons which is 21 as we already discussed.

⇒ The number of electrons in a Scandium atom = 21

⇒ The number of protons in a Scandium atom = 21

⇒ The number of neutrons in a Scandium atom = 24

2. Draw the nucleus of an atom

In this step, we have to draw a small circle that consists of a number of protons and the number of neutrons of a Scandium atom.

nucleus of scandium bohr model

3. Draw the First electron shell

The first electron shell is also called the K-shell, this is the closest shell to the nucleus of an atom and can hold a maximum of two electrons.

As we know, the Scandium atom has a total of 21 electrons. So, put two electrons from it, in the first shell, next to each other.

first electron shell of scandium bohr atom

We have successfully drawn the first shell of the Scandium atom that can hold 2 electrons. As a Scandium atom has a total of 21 electrons, and from 21 electrons we have used two electrons in the first shell.

∴ (21 – 2) = 19 electrons 

Therefore, we are left with 19 electrons, let’s put them in the next shells of the Scandium atom.

4. Draw the Second electron shell

The second shell also called the L-shell that can hold a maximum of 8 electrons. This shell is drawn after the first electron shell.

In the second electron shell, the electrons are added one at a time, starting from the top position and then going in a clockwise direction.

In second shell, electrons are added one at a time in clockwise direction as a clock position – 12 o’clock, 3 o’clock, 6 o’clock, 9 o’clock positions.

electrons placing position in bohr diagram

Once you place the electrons one at a time to each of the four sides(Top – Right – Bottom – Left], start pairing or doubling them.

So, we have 19 remaining electrons of a Scandium atom, and the 2nd shell can only hold a maximum of 8 electrons.

Therefore, put the 8 electrons of the Scandium atom in the 2nd electron shell, start from the top position, put electrons one at a time, and go in a clockwise direction(Top – Right – Bottom – Left). And, finally, pair them up.

2nd electron shell of scandium atom

As we have a total of 21 electrons for the Scandium atom and we placed 2 electrons in the first shell and 8 electrons in the second shell.

∴ [21 – (2+8)] = 11 electrons.

This means we are now left with 11 electrons. So let’s see how we can assign them their appropriate positions in the next shells of the Scandium atom.

Let’s place it in the next shells.

5. Draw the Third electron shell

The third electron shell also called the M-shell can accommodate up to 18 electrons. For the elements in the first few periods of the Periodic Table, the third shell holds up to 8 electrons only. But actually, in totality, it has the capacity to hold 18 electrons.

⇒ The third subshell exhibits this capacity of holding ‘up to 18’’ electrons for atomic numbers greater than 20 such as 21, 22, 23, 24 and so on.

⇒ This 18 electron-holding property of the third shell is specifically important for the d-block elements (Scandium to Zinc).

⇒ The M-shell is divided into subshells (s, p, and d). s can hold only 2 electrons. 6 electrons can be placed in the p-subshell. 2+6 =8, so after these 8 electrons, the rest of the electrons can be placed in the d-subshell of the third shell.

So, it is due to the presence of the d-subshell that the third shell can hold more than 8 and up to 18 electrons in total.

⇒ Another rule to keep in mind is that the filling of electrons follows the Aufbau Principle. Electrons are filled diagonally.

After completely filling the s and p subshell of shell number 3, 2 electrons are accommodated in the s-subshell of the fourth shell. Only then the remaining electrons are placed in the 3d subshell of the third shell.

aufbau principal for filling of electrons in bohr diagram

Let’s see how that’s done.

Out of the 11 electrons left of the Scandium atom, we place 8 electrons in the third shell.

third electron shell in scandium bohr diagram

∴ 11 – 8 = 3.

 

As we already told you, after the 8 electrons in the third shell, we first need to place 2 electrons in the fourth shell and then come back to place the remaining electrons into the third shell again.

Thus, let us place 2 electrons out of the 3 left in the fourth shell first.

6. Draw the Fourth electron shell

Here, we draw the fourth electron shell and put 2 electrons in it. Starting from the top position, put the electrons one at a time while moving in a clockwise direction (Top-Right—Bottom-Left). Here we have only 2 electrons to put in the fourth shell, so one is placed at the top while the other is situated at the right end as shown below.

fourth electron shell in scandium bohr model

∴ 3 – 2 = 1.

 

We are left with only 1 electron so now we will go back and place this 1 electron into the third shell.

7. Place the remaining electrons back into the Third electron shell

The remaining 1 electron of Scandium is placed into the Third electron shell, as shown below.

extra electron in 3d subshell of scandium

Now, this shell has a total of 9 electrons.

The third electron shell keeps on filling in the same manner in the first-row transition metals (Sc to Zn) till this shell is filled to its maximum capacity of holding 18 electrons. But we are not concerned with that in this article.

Bohr model for Scandium (Sc)

So for now, you have the Bohr model of the Scandium atom that contains 21 protons and 24 neutrons in the nucleus region while a total of 21 electrons circulate around the nucleus in specific orbits called shells.

The first electron shell of Scandium has 2 electrons, there are 8 electrons in the second shell, 9 electrons in the third shell, and 2 electrons are present in the fourth shell of the Scandium atom.

That’s all, this is How you can draw the Bohr-Rutherford diagram for atoms.

Now to get the complete detail for the Bohr model of various atoms, please go through the links given below.

Also Check:- 

FAQ

What is the Bohr rutherford diagram?

  • Bohr’s rutherford diagram describes the visual representation of orbiting electrons around the small nucleus.
  • It shows electrons orbiting the nucleus of an atom somewhat like planets orbiting around the sun.
  • In the Bohr diagram, electrons are pictured as traveling in circles at different shells, depending on which element you have.

How to find the valence electron of an atom with the help of the Bohr model?

Valence electrons are found in the outermost shell of an atom and they can take participate in the formation of a chemical bond. These electrons have more energy compared to the inner shell electrons.

From the Bohr rutherford diagram of an atom, we can easily find the number of valence electrons in an atom by looking at its outermost shell.

Let’s take the example of the Neon Bohr model.

How to find valence electron in Bohr diagram

Bohr’s diagram of Neon has only two electron shells (K and L), the inner shell is the K-shell and the outermost shell is L-shell.

Hence, the electrons found in the L-shell of the Neon atom are its valence electrons because it is the outermost shell also called the valence shell.

The L-shell or outer shell of the Neon Bohr model contains 8 electrons, therefore, the number of valence electrons in the Neon atom is 8.

How do determine the number of electron shells a Bohr rutherford diagram contains?

Electron shells also called energy levels, you can find the number of electron shells for an element by knowing its period number in the periodic table.

The elements or atoms in the first period of the periodic table have one energy level or one electron shell, same as, the elements in the second period have two energy levels or two-electron shells, and so on…

First-period elements = One energy level

Second-period elements = Two energy level

Third-period elements = Three energy level

Fourth-period elements = Four energy level

Summary

  • How to Draw a Bohr model of an atom? To draw the Bohr model diagram for any atom, first find the number of protons, electrons, and neutrons of the atom, then, draw the nucleus and write proton and neutrons at the center of it, after that, draw the first electron shell, second electron shell, third electron shell, etc. depending on the availability of electrons.
  • The first shell of the Bohr-Rutherford diagram can hold only 2 electrons, the second shell can hold up to 8 electrons, the third shell can hold a maximum of 18 electrons, and the fourth shell can hold a maximum of 32 electrons.
  • The electron shell of the Bohr model which is closest to the nucleus has less energy and the shell which is farthest away from the nucleus region have more energy.
  • The farthest electron shell from the nucleus region of the Bohr diagram is also known as the Outermost shell which contains the valence electrons of an atom.

About the author

topblogtenz author

Welcome to Topblogtenz, My name is Vishal Goyal. I am an engineer, chemistry tutor, blogger, and founder of topblogtenz.com. I'm a science geek with a passion for life sciences and chemistry. Being a chemistry tutor and having a degree in Engineering, I know how hard it is to learn by yourself, that is why I created a site where you can find help related to science and chemistry before everyone else.

Share it...

Leave a Comment

Your email address will not be published. Required fields are marked *

Connect with us

Get the latest update on Pinterest

© copyright 2022 - topblogtenz.com. All rights Reserved