Bohr model of Gold Atom-How to draw Gold (Au) Bohr-Rutherford diagram?

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The Bohr Model of Gold (Au) has a nucleus that contains 118 neutrons and 79 protons. This nucleus is surrounded by six electron shells namely K-shell, L-shell, M-shell, N-shell, O-shell, and P-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 18 electrons and the 6th shell has 1 electron only.  

NameGold Bohr Model
Number of neutrons118
Number of protons79
Number of electrons79
Total electron shells6
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)18
Electrons in the Sixth shell(P)1

How to draw Bohr Model of Gold (Au)?

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 Gold atom with some simple steps.

Steps to draw the Bohr Model of Gold atom

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

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.

So, the atomic number for Gold is 79, hence, the number of protons in the Gold atom is also 79.

number of protons in gold

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 Gold atom, look at its atomic mass which is 196.9665, rounded off to the nearest whole number 197. The number of protons present in Gold is 79.

∴ Hence, the number of neutrons in Gold atom = (197 – 79) = 118.

number of neutrons in gold

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

As the Gold (Au) atom is neutral thus the number of electrons present in it will be equal to its number of protons i.e., 79, as we discussed earlier.

⇒ The number of electrons in a Gold atom = 79

⇒ The number of protons in the Gold atom = 79

⇒ The number of neutrons in a Gold atom = 118

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 Gold atom.

nucleus of gold bohr model

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 Gold atom has a total of 79 electrons. So we need to put 2 electrons from the 79 available in the first shell, next to each other, as shown below.

first electron shell in gold bohr diagram

Now, that we have successfully drawn the first shell of the Gold atom that can hold 2 electrons, we know that we have used 2 electrons out of the 79 available in the first shell.

(79-2) = 77 electrons.

This shows we are left with 77 electrons that we need to accommodate in the subsequent shells of the Gold 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 77 remaining electrons of a Gold 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 Gold 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 in gold bohr diagram

At this step, out of the 79 electrons of the Gold atom, we have placed 2 electrons in the first shell and 8 electrons in the second shell.

[79 – (2+8)] = 69 electrons.

This means we are now left with 69 electrons. So let’s see how we can assign them their appropriate positions in the next shells of the Gold 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 Gold (Au) is 79. As 79 is visibly greater than 20, this means the M-shell in the Gold 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 in gold

28 electrons are now used up till this step out of the 79 available for drawing the Bohr model of Gold.

79 – [ 2+ 8+ 18] = 79 – 28 = 51.

This leaves behind 51 electrons. Let’s see how we can use these 51 electrons in the next electron shells to obtain an accurate Gold 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 Gold Bohr model, as shown below.

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

fourth electron shell in gold bohr diagram

51 – 32 = 19.

These remaining 19 electrons go into the next shells of the Gold 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.

aufbau principle to fill electrons in bohr diagram of Gold

⇒ The 6s subshell can accommodate a maximum of 2 electrons only. So in the Gold (Au) atom, after filling the 4th shell to its maximum capacity of 32 electrons, 8 electrons go into shell number 5, if 2 electrons can go into shell number 6. 19 – (8+2) = 9, thus these 9 electrons can be consequently placed again in shell number 5 in its 5d subshell.

⇒ But a partially filled 5d subshell with 9 electrons is less stable than a completely filled 5d subshell with 10 electrons. Therefore, as opposed to the distribution of 2 electrons in 6s and 9 electrons in 5d, the Gold atom contains only 1 electron in the 6s subshell while 10 electrons are placed in its 5d subshell.

In short, the 5th shell in the Bohr model of Gold (Au) contains a total of 18 electrons while the 6th electron shell contains 1 electron only.

Let’s see how that is done.

18 electrons are placed in the 5th shell in the Gold Bohr diagram, again in a clockwise manner, as shown below.

5th electron shell in gold bohr model

8. Draw the Sixth electron shell

As a final step, the 6th electron shell is drawn and 1 electron is placed at the top, as shown below.

sixth electron shell in gold bohr model

Now 6th shell has only one electron.

Bohr model for Gold (Au)

Finally, you have the Bohr model of the Gold atom that contains 79 protons and 118 neutrons in the nucleus region while a total of 79 electrons circulate around the nucleus in specific orbits called shells.

The first electron shell of Gold has two electrons, there are eight electrons in the second shell, eighteen electrons in the third, thirty-two electrons in the fourth electron shell, eighteen electrons in the fifth electron shell and one electron is present in the sixth shell of the Gold 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 Gold (Au) represents the 79 electrons present in it, revolving around the small nucleus in specific energy levels called K, L, M, N, O, and P shells.

How many electron shells a Gold 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 Gold (Au) atom belongs to the 6th Period in the periodic table, hence the number of electron shells for the Bohr model of Gold is also 6. There are 6 electron shells in the Gold Bohr model namely K-shell, L-shell, M-shell, N-shell, O-shell, and P-shell.

What is the outer shell of the Bohr diagram of the Gold 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 Gold, its outer shell is shell number 6 i.e., the P-shell containing 1 valence electron. So, there is technically 1 valence electron present in an atom of Gold (Au).

But Gold is a transition metal element and transition metals exhibit a variable valency by using the electrons present in the d-subshell in addition to the outermost electrons for chemical bonding.

Thus Gold (Au) can form an Au3+ ion by losing 3 electrons in addition to the most common Au+1 ion which is formed by losing 1 valence electron. So, you might find written at some places that the valence electrons present in Gold = 1,3.

Summary

  • The Bohr model of Gold (Au) is drawn with six 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 18 electrons again and the sixth shell contains 1 electron.
  • The atomic number of Gold is 79. As Gold (Au) is a neutral atom hence the number of protons and electrons available for its Bohr diagram are equal i.e., 79.
  • The number of neutrons for the Bohr diagram of Gold can be found by subtracting the number of protons from the atomic mass (rounded off to the nearest whole number).
  • The electron configuration of Gold in terms of the shells is [2, 8, 18, 32, 18, 1] while in the standard form it is [Xe] 4f14 5d10 6s1.

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