You are Here: Home >< A-levels

# Why does Argon have 18 electrons watch

1. Why does argon a nobel gas have 18 electrons in total so 8 in the 3rd shell when it should be 18 electrons
2. (Original post by aspen fernandes)
Why does argon a nobel gas have 18 electrons in total so 8 in the 3rd shell when it should be 18 electrons
Like...whatttt??? U r confused!!! Whats ur question?
3. It has 2 in its innermost shell, 8 in the middle shell, and 8 in the outermost shell, 18 electrons
4. (Original post by aspen fernandes)
Why does argon a nobel gas have 18 electrons in total so 8 in the 3rd shell when it should be 18 electrons
Because God wanted it to have 18 electrons.

Spoiler:
Show

it has an electronic configuration of 1s^2 2s^2 2p^6 3s^2 3p^6

5. (Original post by Rohit_Rocks10)
Like...whatttt??? U r confused!!! Whats ur question?
I am saying nobel gases have a full outer shell but argon doesn't
6. (Original post by aspen fernandes)
I am saying nobel gases have a full outer shell but argon doesn't
yes it does, look at my comment above.

s subshell holds 2 electrons

and p holds 6 electrons
7. it does have a full outer shell.
8. Argon does have eight electrons in its valence shell. What makes you think that it doesn't?

9. (Original post by aspen fernandes)
Why does argon a nobel gas have 18 electrons in total so 8 in the 3rd shell when it should be 18 electrons
It does have 8. Who said it doesnt. 2+8+8=18!!!
10. (Original post by YourGoddamnRight)
yes it does, look at my comment above.

s subshell holds 2 electrons

and p holds 6 electrons
well according to A-level Chem textbook and according to Bohr the chemist the 3rd shell has a maximum capacity of 18 electrons but argon doesn't have 18 but 8 electrons.
11. (Original post by aspen fernandes)
Why does argon a nobel gas have 18 electrons in total so 8 in the 3rd shell when it should be 18 electrons
The number of total maximum electrons in the nth innermost shell is 2n^2 so the first shell has 2, 2nd has 3, 3rd has 18 etc

In the case of Argon it's configuration goes 2.8.8 so in the 3rd shell it has eight electrons

Bohr's law states the maximum number of electrons that could theoretically be in a shell (the outermost shell doesn't have to be full) but any element has it's own unique number of total electrons that orbit the nucleus and in the case of argon it happens to be 18 electrons. There can't be 18 electrons in the 3rd shell as that would mean there would be 18+8+2 = 28 electrons in total which is obviously false as argon has 18 electrons altogether
12. Because it had a fight with a bunch of its protons, so now those protons argon and it's a very negative gas

(I'm so sorry I'll leave now)
13. (Original post by Paulington)
Argon does have eight electrons in its valence shell. What makes you think that it doesn't?

i am not saying that it doesn't it does have 8 electrons in the outer shell but argon is a nobel gas right so it should have a full outer shell so third shell should contain 18 but argon only has 8
14. (Original post by aspen fernandes)
i am not saying that it doesn't it does have 8 electrons in the outer shell but argon is a nobel gas right so it should have a full outer shell so third shell should contain 18 but argon only has 8
But an outer shell can only hold 8 electrons maximum, not 18

Argon has 18 electrons IN TOTAL not just on its outer shell
15. (Original post by m-k1)
But an outer shell can only hold 8 electrons maximum, not 18

Argon has 18 electrons IN TOTAL not just on its outer shell
if you haven't done AS chem then if you do it then you'll learn that the 3rd shell actually contains 18 electrons, not 8 and the 4th shell contains 32 electrons.
16. (Original post by aspen fernandes)
I am saying nobel gases have a full outer shell but argon doesn't
It does
17. (Original post by aspen fernandes)
well according to A-level Chem textbook and according to Bohr the chemist the 3rd shell has a maximum capacity of 18 electrons but argon doesn't have 18 but 8 electrons.
I think I understand what you mean:

I'm guessing you are talking about the 3d after the 4s. You're correct that the third shell has a potential for 18 electrons. The 3p^6 (last subshell) fills up the third subshell, if more electrons are added then it would create a 4th shell (4s), then if more electrons are added they would be added to the third shell.
18. (Original post by aspen fernandes)
if you haven't done AS chem then if you do it then you'll learn that the 3rd shell actually contains 18 electrons, not 8 and the 4th shell contains 32 electrons.
I've looked about online, it keeps talking about s and p shells, (Idk what that is..)
but basically what they're saying is that the rule doesn't apply to the noble gases and that it has 2,8,8 still.
19. Argon is 1s2, 2s2, 2p6, 3s2, 3p6. The third shell isn't full as it doesn't have any electrons in d-orbitals, but it does have a full p-sub-shell in the 3rd shell so that has the same effect as in previous noble gases. The whole "full outer-shell" thing only really applies to Helium and Neon, all noble gases after them are like Argon in that they have a full p-sub-shell in their outer shell but no electrons in the d-sub-shell. They're still inert, as they are noble gases.
20. You seem to be confusing the whole "stable octet" thing with electron configuration.

Argon has eight electrons in its outer shell because the third quantum level of orbitals is full. You will learn in A levels that electrons are not as simple as you think, you have multiple orbitals (s, p, d, f, etc) and a "full outer shell" means that the outer (highest energy) quantum level is full.

For example, this is the electron configuration of Argon:

Notice the third quantum level is full (excluding d-orbitals, they're a bit of a special thing) and so it does indeed have a full shell! .

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: October 18, 2017
Today on TSR

### Uni league tables

Do they actually matter?

### University open days

• University of Warwick
Sat, 20 Oct '18
• University of Sheffield
Sat, 20 Oct '18
• Edge Hill University
Faculty of Health and Social Care Undergraduate
Sat, 20 Oct '18
Poll

## All the essentials

### Student life: what to expect

What it's really like going to uni

### Essay expert

Learn to write like a pro with our ultimate essay guide.

### Create a study plan

Get your head around what you need to do and when with the study planner tool.

### Resources by subject

Everything from mind maps to class notes.

### Study tips from A* students

Students who got top grades in their A-levels share their secrets