Bohr model of Uranium Atom-How to draw Uranium (U) Bohr-Rutherford diagram

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The Bohr Model of Uranium (U) has a nucleus that contains 146 neutrons and 92 protons. This nucleus is surrounded by seven electron shells namely K-shell, L-shell, M-shell, N-shell, O-shell, P-shell, and Q-shell. The 1st shell has 2 electrons, the 2nd shell has 8 electrons, the 3rd shell has 18 electrons, the 4th shell contains 32 electrons, the 5th shell has 21 electrons, the 6th shell has 9 electrons and the 7th shell has 2 electrons only.  

NameUranium Bohr Model
Number of neutrons146
Number of protons92
Number of electrons92
Total electron shells7
Electron in the First shell(K)2
Electrons in the Second shell(L)8
Electrons in the Third shell(M)18
Electrons in the Fourth shell(N)32
Electrons in the Fifth shell(O)21
Electrons in the Sixth shell(P)9
Electrons in the Seventh shell(Q)2

How to draw Bohr Model of Uranium (U)?

Bohr model 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.

Bohr’s diagram is very interesting and easy to draw. Here, we will draw the Bohr model of the Uranium atom with some simple steps.

Steps to draw the Bohr Model of Uranium atom

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

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

To find the number of protons an atom contains, just look at its atomic number.

If the atomic number of atom is 45, then proton will also be 45, if atomic number is 46, then proton will also be 46.

As the atomic number of Uranium is 92 so the number of protons present in it is also 92.

number of protons in uranium

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

For example, An atom have 33.988 atomic mass and 16 protons.

Then, to find the number of neutron, round the atomic mass to the near whole number, so, atomic mass 33.988 round to 34.

= (34 – 16 protons) = 18 number of neutrons in the atom

Now, to get the number of neutrons in a Uranium atom, look at its atomic mass which is 238.029 rounded off to the nearest whole number it is 238. The number of protons present in Uranium is 92.

∴ Hence, the number of neutrons in Uranium atom = (238-92) = 146.

number of neutrons in uranium

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

As the Uranium (U) atom is neutral thus the number of electrons present in it will be equal to its number of protons i.e., 92, as we discussed earlier.

⇒ The number of electrons in a Uranium atom = 92

⇒ The number of protons in the Uranium atom = 92

⇒ The number of neutrons in a Uranium atom = 146

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

2. Draw the nucleus of an atom

A nucleus is a dense and small region that contains the number of protons and neutrons 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 Uranium atom.

nucleus of uranium bohr diagram

3. Draw the First electron shell

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

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 identified, the Uranium atom has a total of 92 electrons. So we need to put 2 electrons from the 92 available in the first shell, next to each other, as shown below.

1st electron shell of uranium

Now, that we have successfully drawn the first shell of the Uranium atom that can hold 2 electrons, we know that we have used 2 electrons out of the 92 available in the first shell.

(92-2) = 90 electrons.

This shows we are left with 90 electrons that we need to accommodate in the subsequent shells of the Uranium 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.

As we have 90 remaining electrons of a Uranium atom, out of which the second shell can hold only a maximum of 8 valence electrons.

Thus, we place the next 8 electrons of the Uranium atom in the second shell. Start from the top position and put electrons one at a time, moving in a clockwise direction (Top-Right-Bottom-Left), and finally pair them up.

2nd electron shell of uranium

At this step, out of the 92 electrons of the Uranium atom, we have placed 2 electrons in the first shell and 8 electrons in the second shell.

[92 – (2+8)] = 82 electrons.

This means we are now left with 82 electrons. So let’s see how we can assign them their appropriate positions in the next shells of the Uranium atom.

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, 25, 26, and so on.

⇒ The atomic number of Uranium (U) is 92. As 92 is visibly greater than 20, this means the M-shell in the Uranium Bohr model will be filled to its maximum capacity by accommodating a total of 18 electrons, as shown below.

The electrons are placed in a clockwise manner, as we discussed in step 4. Starting from the top position, put the electrons one at a time while moving in a clockwise direction (Top – Right — Bottom – Left), before pairing up the electrons.

3rd electron shell of uranium

28 electrons are now used up till this step out of the 92 available for drawing the Bohr model of Uranium.

92 – [ 2+ 8+ 18] = 92-28 = 64.

This leaves behind 64 electrons. Let’s see how we can use these 64 electrons in the next electron shells to obtain an accurate Uranium Bohr model.

6. Draw the Fourth electron shell

⇒ The fourth electron shell i.e., N-shell has a maximum capacity of holding 32 electrons in total. It consists of s, p, d, and f subshells.

The s subshell can contain 2 electrons, 6 electrons can be placed in the p-subshell, 10 electrons can be placed in the d-subshell while a total of 14 electrons can be accommodated in the f-subshell of shell number 4. 2+6+10+14 makes a total of 32 electrons.

So, 32 electrons are now placed at this step into the Fourth electron shell of the Uranium Bohr model, as shown below.

The clockwise electron filling order i.e., top-right-bottom-left is strictly followed here as well.

4th electron shell of uranium bohr model

64 – 32 = 32.  

These remaining 32 electrons go into the next shells of the Uranium Bohr model, as discussed in the following steps.

7. Draw the Fifth electron shell

The Fifth electron shell has a maximum capacity of containing a total of 50 electrons as per the rule of filling 2 electrons in 5s, 6 electrons in 5p, 10 electrons in 5d, 14 electrons in 5f, and 18 electrons in 5g subshell. But the existence of the 5g subshell is just a hypothetical situation. No elements exist so far that have the 5g subshell.

⇒ So in reality, in any atom, the 5th electron shell can also only have a total of 32 electrons if filled to its maximum capacity.

⇒ Another tricky part here is that the electrons are filled diagonally as per the Aufbau principle. The Aufbau principle states that the s-subshell of shell number 6 is filled prior to placing electrons in the d-subshell of shell number 5.

electron filling order in uranium bohr model

⇒ A total of 2 electrons can be placed in the 6s subshell. After these 2 electrons, the remaining electrons of Uranium go back into the 5th shell. But the Aufbau diagram shown above illustrates that electrons start occupying 6p and 7s subshells before completing filling shell number 5.

⇒ In short, a total of 18 electrons are accommodated in the 5th shell of Uranium as per the distribution of 2 electrons in 5s, 6 electrons in 5p, and 10 electrons in 5d before electrons start occupying the 6th and 7th electron shells. 3 electrons then go it into the 5f subshell of shell number 5 after filling 6s,6p, and 7s.

2+6+10+3 = 21 electrons

But here while drawing the Bohr diagram, we are placing all the 21 electrons to be accommodated in the fifth electron shell in a single step, again following the clockwise rule, as shown below.

5th electron shell in uranium bohr diagram

32– 21 = 11.  

8. Draw the Sixth electron shell

Out of the 11 remaining electrons, 8 electrons go into the 6th electron shell i.e., the P-shell of the Uranium (U) Bohr model. The 6s and 6p subshells are filled with 2 and 6 electrons respectively.

6th electron shell of uranium bohr model

11-8 = 3

9. Draw the Seventh electron shell

Out of the remaining 3 electrons, two electrons are placed in the 7th electron shell i.e., the Q-shell of the Uranium (U) Bohr model.

7th electron shell in uranium bohr diagram

3– 2 = 1  

This remaining one electron is placed back into the 6th electron shell in 6d as per the Aufbau principle.

10. Place the one remaining electron back into the Sixth electron shell

extra electrons placed in uranium bohr diagram

In this way, the Sixth electron shell of Uranium (U) contains a total of 9 electrons.

Bohr model for Uranium (U)

Finally, the good news is that after all the hard work, we finally have the correct Bohr model of the Uranium atom that contains 92 protons and 146 neutrons in the nucleus region while a total of 92 electrons circulate around the nucleus in specific orbits called shells.

The first electron shell of Uranium has two electrons, there are eight electrons in the second shell, eighteen electrons in the third, thirty-two electrons in the fourth electron shell, twenty-one electrons in the fifth electron shell, nine electrons in the sixth shell, and two one electrons are present in the seventh shell of the Uranium atom.

Also Read:-

Also check :- Bohr model for all elements of Periodic table

FAQ

What is the Bohr diagram?

The Bohr diagram formally called a Bohr-Rutherford model is a visual representation of orbiting electrons around the small nucleus of an atom. For example, the Bohr diagram of Uranium (U) represents the 92 electrons present in it, revolving around the small nucleus in specific energy levels called K, L, M, N, O, P, and Q shells.

How many electron shells a Uranium Bohr model contains?

Electron shells are 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, similarly, the elements in the second period have two energy levels or two electron shells, and so on.

As the Uranium (U) atom belongs to the 7th Period in the periodic table, hence the number of electron shells for the Bohr model of Uranium is also 7. There are 7 electron shells in the Uranium Bohr model namely K-shell, L-shell, M-shell, N-shell, O-shell, P-shell and Q-shell.

What is the outer shell of the Bohr diagram of the Uranium atom?  

The outermost shell also called the valence shell is the shell that contains the valence electrons of an atom.

According to the Bohr diagram of Uranium, its outer shell is shell number 7 i.e., the Q-shell containing 2 valence electrons. So, there are technically 2 valence electrons present in an atom of Uranium (U).

But Uranium is an inner-transition metal element and transition metals exhibit a variable valency by using the electrons present in the d-subshell in addition to their outermost electrons for chemical bonding. Thus, the most common ions of Uranium are U2+, U3+, U4+, U5+ and U6+. In forming the U6+ ion, the Uranium atom has lost 6 valence electrons. Therefore, we say that there are a total of 6 valence electrons in Uranium.

Summary

  • The Bohr model of Uranium (U) is drawn with seven electron shells, the first shell contains 2 electrons, the second shell contains 8 electrons, the third shell contains 18 electrons, the fourth shell contains 32 electrons, the fifth shell contains 21 electrons, the sixth shell contains 9 electrons and the seventh shell contains 2 electrons.
  • The atomic number of Uranium is 92. As Uranium (U) is a neutral atom hence the number of protons and electrons available for its Bohr diagram are equal i.e., 92.
  • The number of neutrons for the Bohr diagram of Uranium can be found by subtracting the number of protons from the atomic mass (rounded off to the nearest whole number).
  • The electron configuration of Uranium in terms of the shells is [2,8,18, 32, 21,9,2] while in the standard form it is [Rn] 5f3 6d1 7s2.

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